Scala Standard Library2.12.21 < Back
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# Packages

-  package root

  This is the documentation for the Scala standard library.

  This is the documentation for the Scala standard library.

  #### Package structure

  The scala package contains core types like `Int`, `Float`, `Array` or `Option` which are accessible in all Scala compilation units without explicit qualification or imports.

  Notable packages include:

  - `scala.collection` and its sub-packages contain Scala's collections framework
    - `scala.collection.immutable` - Immutable, sequential data-structures such as `Vector`, `List`, `Range`, `HashMap` or `HashSet`
    - `scala.collection.mutable` - Mutable, sequential data-structures such as `ArrayBuffer`, `StringBuilder`, `HashMap` or `HashSet`
    - `scala.collection.concurrent` - Mutable, concurrent data-structures such as `TrieMap`
    - `scala.collection.parallel.immutable` - Immutable, parallel data-structures such as `ParVector`, `ParRange`, `ParHashMap` or `ParHashSet`
    - `scala.collection.parallel.mutable` - Mutable, parallel data-structures such as `ParArray`, `ParHashMap`, `ParTrieMap` or `ParHashSet`
  - `scala.concurrent` - Primitives for concurrent programming such as `Futures` and `Promises`
  - `scala.io` - Input and output operations
  - `scala.math` - Basic math functions and additional numeric types like `BigInt` and `BigDecimal`
  - `scala.sys` - Interaction with other processes and the operating system
  - `scala.util.matching` - Regular expressions

  Other packages exist. See the complete list on the right.

  Additional parts of the standard library are shipped as separate libraries. These include:

  - `scala.reflect` - Scala's reflection API (scala-reflect.jar)
  - `scala.xml` - XML parsing, manipulation, and serialization (scala-xml.jar)
  - `scala.swing` - A convenient wrapper around Java's GUI framework called Swing (scala-swing.jar)
  - `scala.util.parsing` - Parser combinators (scala-parser-combinators.jar)

  #### Automatic imports

  Identifiers in the scala package and the `scala.Predef` object are always in scope by default.

  Some of these identifiers are type aliases provided as shortcuts to commonly used classes. For example, `List` is an alias for `scala.collection.immutable.List`.

  Other aliases refer to classes provided by the underlying platform. For example, on the JVM, `String` is an alias for `java.lang.String`.

  Definition Classes
    root
-  package scala

  Core Scala types.

  Core Scala types. They are always available without an explicit import.

  Definition Classes
    root
-  package collection

  Contains the base traits and objects needed to use and extend Scala's collection library.

  Contains the base traits and objects needed to use and extend Scala's collection library.

  #### Guide

  A detailed guide for using the collections library is available at http://docs.scala-lang.org/overviews/collections/introduction.html. Developers looking to extend the collections library can find a description of its architecture at http://docs.scala-lang.org/overviews/core/architecture-of-scala-collections.html.

  #### Using Collections

  It is convenient to treat all collections as either a scala.collection.Traversable or scala.collection.Iterable, as these traits define the vast majority of operations on a collection.

  Collections can, of course, be treated as specifically as needed, and the library is designed to ensure that the methods that transform collections will return a collection of the same type:

      scala> val array = Array(1,2,3,4,5,6)
      array: Array[Int] = Array(1, 2, 3, 4, 5, 6)

      scala> array map { _.toString }
      res0: Array[String] = Array(1, 2, 3, 4, 5, 6)

      scala> val list = List(1,2,3,4,5,6)
      list: List[Int] = List(1, 2, 3, 4, 5, 6)

      scala> list map { _.toString }
      res1: List[String] = List(1, 2, 3, 4, 5, 6)

  #### Creating Collections

  The most common way to create a collection is to use its companion object as a factory. The three most commonly used collections are scala.collection.Seq, scala.collection.immutable.Set, and scala.collection.immutable.Map. They can be used directly as shown below since their companion objects are all available as type aliases in either the scala package or in `scala.Predef`. New collections are created like this:

      scala> val seq = Seq(1,2,3,4,1)
      seq: Seq[Int] = List(1, 2, 3, 4, 1)

      scala> val set = Set(1,2,3,4,1)
      set: scala.collection.immutable.Set[Int] = Set(1, 2, 3, 4)

      scala> val map = Map(1 -> "one", 2 -> "two", 3 -> "three", 2 -> "too")
      map: scala.collection.immutable.Map[Int,String] = Map(1 -> one, 2 -> too, 3 -> three)

  It is also typical to prefer the scala.collection.immutable collections over those in scala.collection.mutable; the types aliased in the `scala.Predef` object are the immutable versions.

  Also note that the collections library was carefully designed to include several implementations of each of the three basic collection types. These implementations have specific performance characteristics which are described in the guide.

  The concrete parallel collections also have specific performance characteristics which are described in the parallel collections guide

  ##### Converting to and from Java Collections

  The scala.collection.JavaConverters object provides a collection of decorators that allow converting between Scala and Java collections using `asScala` and `asJava` methods.

  Definition Classes
    scala
-  package concurrent
  Definition Classes
    collection
-  package convert
  Definition Classes
    collection
-  package generic
  Definition Classes
    collection
-  package immutable
  Definition Classes
    collection
-  package mutable
  Definition Classes
    collection
-  package parallel

  Package object for parallel collections.

  Package object for parallel collections.

  Definition Classes
    collection
-  package script
  Definition Classes
    collection
- +:
- :+
- AbstractIterable
- AbstractIterator
- AbstractMap
- AbstractSeq
- AbstractSet
- AbstractTraversable
- BitSet
- BitSetLike
- BufferedIterator
- CustomParallelizable
- DefaultMap
- GenIterable
- GenIterableLike
- GenMap
- GenMapLike
- GenSeq
- GenSeqLike
- GenSet
- GenSetLike
- GenTraversable
- GenTraversableLike
- GenTraversableOnce
- IndexedSeq
- IndexedSeqLike
- IndexedSeqOptimized
- Iterable
- IterableLike
- IterableProxy
- IterableProxyLike
- IterableView
- IterableViewLike
- Iterator
- JavaConversions
- JavaConverters
- LinearSeq
- LinearSeqLike
- LinearSeqOptimized
- Map
- MapLike
- MapProxy
- MapProxyLike
- Parallel
- Parallelizable
- Searching
- Seq
- SeqLike
- SeqProxy
- SeqProxyLike
- SeqView
- SeqViewLike
- Set
- SetLike
- SetProxy
- SetProxyLike
- SortedMap
- SortedMapLike
- SortedSet
- SortedSetLike
- Traversable
- TraversableLike
- TraversableOnce
- TraversableProxy
- TraversableProxyLike
- TraversableView
- TraversableViewLike
- ViewMkString

t

scala.collection

# IndexedSeqOptimized 

###

#### trait IndexedSeqOptimized[+A, +Repr] extends IndexedSeqLike[A, Repr]

A template trait for indexed sequences of type `IndexedSeq[A]` which optimizes the implementation of several methods under the assumption of fast random access.

Indexed sequences support constant-time or near constant-time element access and length computation. They are defined in terms of abstract methods `apply` for indexing and `length`.

Indexed sequences do not add any new methods to `Seq`, but promise efficient implementations of random access patterns.

Self Type
  IndexedSeqOptimized[A, Repr]
Source
  IndexedSeqOptimized.scala

Linear Supertypes
IndexedSeqLike[A, Repr], SeqLike[A, Repr], GenSeqLike[A, Repr], IterableLike[A, Repr], GenIterableLike[A, Repr], TraversableLike[A, Repr], GenTraversableLike[A, Repr], Parallelizable[A, ParSeq[A]], TraversableOnce[A], GenTraversableOnce[A], FilterMonadic[A, Repr], HasNewBuilder[A, Repr], Equals, Any
Known Subclasses
StringLike, StringOps, WrappedString, ArrayBuffer, ArrayLike, ArrayOps, ofBoolean, ofByte, ofChar, ofDouble, ofFloat, ofInt, ofLong, ofRef, ofShort, ofUnit, ArraySeq, ArrayStack, IndexedSeqOptimized, IndexedSeqView, DroppedWhile, Filtered, Reversed, Sliced, TakenWhile, Transformed, ResizableArray, StringBuilder, WrappedArray, ofBoolean, ofByte, ofChar, ofDouble, ofFloat, ofInt, ofLong, ofRef, ofShort, ofUnit, Script
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Ordering

1. Alphabetic
2. By Inheritance

Inherited

1. IndexedSeqOptimized
2. IndexedSeqLike
3. SeqLike
4. GenSeqLike
5. IterableLike
6. GenIterableLike
7. TraversableLike
8. GenTraversableLike
9. Parallelizable
10. TraversableOnce
11. GenTraversableOnce
12. FilterMonadic
13. HasNewBuilder
14. Equals
15. Any

Implicitly

1. by CollectionsHaveToParArray
2. by MonadOps
3. by any2stringadd
4. by StringFormat
5. by Ensuring
6. by ArrowAssoc
7. by alternateImplicit

1. Hide All
2. Show All

Visibility

1. Public
2. All

### Type Members

1.  class Elements extends AbstractIterator[A] with BufferedIterator[A] with Serializable

   The class of the iterator returned by the `iterator` method.

   The class of the iterator returned by the `iterator` method. multiple `take`, `drop`, and `slice` operations on this iterator are bunched together for better efficiency.

   Attributes
     protected
   Definition Classes
     IndexedSeqLike
   Annotations
     @SerialVersionUID()
2.  type Self = Repr

   The type implementing this traversable

   The type implementing this traversable

   Attributes
     protected[this]
   Definition Classes
     TraversableLike
3.  class WithFilter extends FilterMonadic[A, Repr]

   A class supporting filtered operations.

   A class supporting filtered operations. Instances of this class are returned by method `withFilter`.

   Definition Classes
     TraversableLike

### Abstract Value Members

1.  abstract def apply(idx: Int): A

   Selects an element by its index in the sequence.

   Selects an element by its index in the sequence.

   Example:

       scala> val x = List(1, 2, 3, 4, 5)
       x: List[Int] = List(1, 2, 3, 4, 5)

       scala> x(3)
       res1: Int = 4

   idx

     The index to select.

   returns

     the element of this sequence at index `idx`, where `0` indicates the first element.

   Definition Classes
     SeqLike → GenSeqLike
   Exceptions thrown

     `IndexOutOfBoundsException` if `idx` does not satisfy `0 <= idx < length`.

2.  abstract def getClass(): Class[_]

   Returns the runtime class representation of the object.

   Returns the runtime class representation of the object.

   returns

     a class object corresponding to the runtime type of the receiver.

   Definition Classes
     Any
3.  abstract def length: Int

   The length of the sequence.

   The length of the sequence.

   Note: will not terminate for infinite-sized collections.

   Note: `xs.length` and `xs.size` yield the same result.

   returns

     the number of elements in this sequence.

   Definition Classes
     SeqLike → GenSeqLike
   Exceptions thrown

     `IllegalArgumentException` if the length of the sequence cannot be represented in an `Int`, for example, `(-1 to Int.MaxValue).length`.

4.  abstract def newBuilder: Builder[A, Repr]

   Creates a new builder for this collection type.

   Creates a new builder for this collection type.

   Attributes
     protected[this]
   Definition Classes
     TraversableLike → HasNewBuilder
5.  abstract def seq: IndexedSeq[A]

   A version of this collection with all of the operations implemented sequentially (i.e., in a single-threaded manner).

   A version of this collection with all of the operations implemented sequentially (i.e., in a single-threaded manner).

   This method returns a reference to this collection. In parallel collections, it is redefined to return a sequential implementation of this collection. In both cases, it has O(1) complexity.

   returns

     a sequential view of the collection.

   Definition Classes
     IndexedSeqLike → GenSeqLike → Parallelizable → TraversableOnce → GenTraversableOnce

### Concrete Value Members

1.  final def !=(arg0: Any): Boolean

   Test two objects for inequality.

   Test two objects for inequality.

   returns

     `true` if !(this == that), false otherwise.

   Definition Classes
     Any
2.  final def ##(): Int

   Equivalent to `x.hashCode` except for boxed numeric types and `null`.

   Equivalent to `x.hashCode` except for boxed numeric types and `null`. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For `null` returns a hashcode where `null.hashCode` throws a `NullPointerException`.

   returns

     a hash value consistent with ==

   Definition Classes
     Any
3.  def +(other: String): String
   Implicit
     This member is added by an implicit conversion from IndexedSeqOptimized[A, Repr] to any2stringadd[IndexedSeqOptimized[A, Repr]] performed by method any2stringadd in scala.Predef.
   Definition Classes
     any2stringadd
4.  def ++[B >: A, That](that: GenTraversableOnce[B])(implicit bf: CanBuildFrom[Repr, B, That]): That

   Returns a new traversable collection containing the elements from the left hand operand followed by the elements from the right hand operand.

   Returns a new traversable collection containing the elements from the left hand operand followed by the elements from the right hand operand. The element type of the traversable collection is the most specific superclass encompassing the element types of the two operands.

   B

     the element type of the returned collection.

   That

     the class of the returned collection. Where possible, `That` is the same class as the current collection class `Repr`, but this depends on the element type `B` being admissible for that class, which means that an implicit instance of type `CanBuildFrom[Repr, B, That]` is found.

   that

     the traversable to append.

   bf

     an implicit value of class `CanBuildFrom` which determines the result class `That` from the current representation type `Repr` and the new element type `B`.

   returns

     a new collection of type `That` which contains all elements of this traversable collection followed by all elements of `that`.

   Definition Classes
     TraversableLike → GenTraversableLike
5.  def ++:[B >: A, That](that: Traversable[B])(implicit bf: CanBuildFrom[Repr, B, That]): That

   As with `++`, returns a new collection containing the elements from the left operand followed by the elements from the right operand.

   As with `++`, returns a new collection containing the elements from the left operand followed by the elements from the right operand.

   It differs from `++` in that the right operand determines the type of the resulting collection rather than the left one. Mnemonic: the COLon is on the side of the new COLlection type.

   Example:

       scala> val x = List(1)
       x: List[Int] = List(1)

       scala> val y = LinkedList(2)
       y: scala.collection.mutable.LinkedList[Int] = LinkedList(2)

       scala> val z = x ++: y
       z: scala.collection.mutable.LinkedList[Int] = LinkedList(1, 2)

   This overload exists because: for the implementation of `++:` we should reuse that of `++` because many collections override it with more efficient versions.

   Since `TraversableOnce` has no `++` method, we have to implement that directly, but `Traversable` and down can use the overload.

   B

     the element type of the returned collection.

   That

     the class of the returned collection. Where possible, `That` is the same class as the current collection class `Repr`, but this depends on the element type `B` being admissible for that class, which means that an implicit instance of type `CanBuildFrom[Repr, B, That]` is found.

   that

     the traversable to append.

   bf

     an implicit value of class `CanBuildFrom` which determines the result class `That` from the current representation type `Repr` and the new element type `B`.

   returns

     a new collection of type `That` which contains all elements of this traversable collection followed by all elements of `that`.

   Definition Classes
     TraversableLike
6.  def ++:[B](that: TraversableOnce[B]): IndexedSeq[B]

   [use case] As with `++`, returns a new collection containing the elements from the left operand followed by the elements from the right operand.

   [use case]

   As with `++`, returns a new collection containing the elements from the left operand followed by the elements from the right operand.

   It differs from `++` in that the right operand determines the type of the resulting collection rather than the left one. Mnemonic: the COLon is on the side of the new COLlection type.

   Example:

       scala> val x = List(1)
       x: List[Int] = List(1)

       scala> val y = LinkedList(2)
       y: scala.collection.mutable.LinkedList[Int] = LinkedList(2)

       scala> val z = x ++: y
       z: scala.collection.mutable.LinkedList[Int] = LinkedList(1, 2)

   B

     the element type of the returned collection.

   that

     the traversable to append.

   returns

     a new sequence which contains all elements of this sequence followed by all elements of `that`.

   Definition Classes
     TraversableLike
    Full Signature

   #### def ++:[B >: A, That](that: TraversableOnce[B])(implicit bf: CanBuildFrom[Repr, B, That]): That

7.  def +:(elem: A): IndexedSeq[A]

   [use case] A copy of the sequence with an element prepended.

   [use case]

   A copy of the sequence with an element prepended.

   Note that :-ending operators are right associative (see example). A mnemonic for `+:` vs. `:+` is: the COLon goes on the COLlection side.

   Also, the original sequence is not modified, so you will want to capture the result.

   Example:

       scala> val x = List(1)
       x: List[Int] = List(1)

       scala> val y = 2 +: x
       y: List[Int] = List(2, 1)

       scala> println(x)
       List(1)

   elem

     the prepended element

   returns

     a new sequence consisting of `elem` followed by all elements of this sequence.

   Definition Classes
     SeqLike → GenSeqLike
    Full Signature

   #### def +:[B >: A, That](elem: B)(implicit bf: CanBuildFrom[Repr, B, That]): That

8.  def ->[B](y: B): (IndexedSeqOptimized[A, Repr], B)
   Implicit
     This member is added by an implicit conversion from IndexedSeqOptimized[A, Repr] to ArrowAssoc[IndexedSeqOptimized[A, Repr]] performed by method ArrowAssoc in scala.Predef.
   Definition Classes
     ArrowAssoc
   Annotations
     @inline()
9.  def :+(elem: A): IndexedSeq[A]

   [use case] A copy of this sequence with an element appended.

   [use case]

   A copy of this sequence with an element appended.

   A mnemonic for `+:` vs. `:+` is: the COLon goes on the COLlection side.

   Example:

       scala> val a = List(1)
       a: List[Int] = List(1)

       scala> val b = a :+ 2
       b: List[Int] = List(1, 2)

       scala> println(a)
       List(1)

   elem

     the appended element

   returns

     a new sequence consisting of all elements of this sequence followed by `elem`.

   Definition Classes
     SeqLike → GenSeqLike
    Full Signature

   #### def :+[B >: A, That](elem: B)(implicit bf: CanBuildFrom[Repr, B, That]): That

10.  final def ==(arg0: Any): Boolean

    Test two objects for equality.

    Test two objects for equality. The expression `x == that` is equivalent to `if (x eq null) that eq null else x.equals(that)`.

    returns

      `true` if the receiver object is equivalent to the argument; `false` otherwise.

    Definition Classes
      Any
11.  def addString(b: StringBuilder): StringBuilder

    Appends all elements of this traversable or iterator to a string builder.

    Appends all elements of this traversable or iterator to a string builder. The written text consists of the string representations (w.r.t. the method `toString`) of all elements of this traversable or iterator without any separator string.

    Example:

        scala> val a = List(1,2,3,4)
        a: List[Int] = List(1, 2, 3, 4)

        scala> val b = new StringBuilder()
        b: StringBuilder =

        scala> val h = a.addString(b)
        h: StringBuilder = 1234

    b

      the string builder to which elements are appended.

    returns

      the string builder `b` to which elements were appended.

    Definition Classes
      TraversableOnce
12.  def addString(b: StringBuilder, sep: String): StringBuilder

    Appends all elements of this traversable or iterator to a string builder using a separator string.

    Appends all elements of this traversable or iterator to a string builder using a separator string. The written text consists of the string representations (w.r.t. the method `toString`) of all elements of this traversable or iterator, separated by the string `sep`.

    Example:

        scala> val a = List(1,2,3,4)
        a: List[Int] = List(1, 2, 3, 4)

        scala> val b = new StringBuilder()
        b: StringBuilder =

        scala> a.addString(b, ", ")
        res0: StringBuilder = 1, 2, 3, 4

    b

      the string builder to which elements are appended.

    sep

      the separator string.

    returns

      the string builder `b` to which elements were appended.

    Definition Classes
      TraversableOnce
13.  def addString(b: StringBuilder, start: String, sep: String, end: String): StringBuilder

    Appends all elements of this traversable or iterator to a string builder using start, end, and separator strings.

    Appends all elements of this traversable or iterator to a string builder using start, end, and separator strings. The written text begins with the string `start` and ends with the string `end`. Inside, the string representations (w.r.t. the method `toString`) of all elements of this traversable or iterator are separated by the string `sep`.

    Example:

        scala> val a = List(1,2,3,4)
        a: List[Int] = List(1, 2, 3, 4)

        scala> val b = new StringBuilder()
        b: StringBuilder =

        scala> a.addString(b , "List(" , ", " , ")")
        res5: StringBuilder = List(1, 2, 3, 4)

    b

      the string builder to which elements are appended.

    start

      the starting string.

    sep

      the separator string.

    end

      the ending string.

    returns

      the string builder `b` to which elements were appended.

    Definition Classes
      TraversableOnce
14.  def aggregate[B](z: ⇒ B)(seqop: (B, A) ⇒ B, combop: (B, B) ⇒ B): B

    Aggregates the results of applying an operator to subsequent elements.

    Aggregates the results of applying an operator to subsequent elements.

    This is a more general form of `fold` and `reduce`. It is similar to `foldLeft` in that it doesn't require the result to be a supertype of the element type. In addition, it allows parallel collections to be processed in chunks, and then combines the intermediate results.

    `aggregate` splits the traversable or iterator into partitions and processes each partition by sequentially applying `seqop`, starting with `z` (like `foldLeft`). Those intermediate results are then combined by using `combop` (like `fold`). The implementation of this operation may operate on an arbitrary number of collection partitions (even 1), so `combop` may be invoked an arbitrary number of times (even 0).

    As an example, consider summing up the integer values of a list of chars. The initial value for the sum is 0. First, `seqop` transforms each input character to an Int and adds it to the sum (of the partition). Then, `combop` just needs to sum up the intermediate results of the partitions:

        List('a', 'b', 'c').aggregate(0)({ (sum, ch) => sum + ch.toInt }, { (p1, p2) => p1 + p2 })

    B

      the type of accumulated results

    z

      the initial value for the accumulated result of the partition - this will typically be the neutral element for the `seqop` operator (e.g. `Nil` for list concatenation or `0` for summation) and may be evaluated more than once

    seqop

      an operator used to accumulate results within a partition

    combop

      an associative operator used to combine results from different partitions

    Definition Classes
      TraversableOnce → GenTraversableOnce
15.  final def asInstanceOf[T0]: T0

    Cast the receiver object to be of type `T0`.

    Cast the receiver object to be of type `T0`.

    Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression `1.asInstanceOf[String]` will throw a `ClassCastException` at runtime, while the expression `List(1).asInstanceOf[List[String]]` will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.

    returns

      the receiver object.

    Definition Classes
      Any
    Exceptions thrown

      `ClassCastException` if the receiver object is not an instance of the erasure of type `T0`.

16.  def canEqual(that: Any): Boolean

    Method called from equality methods, so that user-defined subclasses can refuse to be equal to other collections of the same kind.

    Method called from equality methods, so that user-defined subclasses can refuse to be equal to other collections of the same kind.

    that

      The object with which this iterable collection should be compared

    returns

      `true`, if this iterable collection can possibly equal `that`, `false` otherwise. The test takes into consideration only the run-time types of objects but ignores their elements.

    Definition Classes
      IterableLike → Equals
17.  def collect[B](pf: PartialFunction[A, B]): IndexedSeq[B]

    [use case] Builds a new collection by applying a partial function to all elements of this sequence on which the function is defined.

    [use case]

    Builds a new collection by applying a partial function to all elements of this sequence on which the function is defined.

    B

      the element type of the returned collection.

    pf

      the partial function which filters and maps the sequence.

    returns

      a new sequence resulting from applying the given partial function `pf` to each element on which it is defined and collecting the results. The order of the elements is preserved.

    Definition Classes
      TraversableLike → GenTraversableLike
     Full Signature

    #### def collect[B, That](pf: PartialFunction[A, B])(implicit bf: CanBuildFrom[Repr, B, That]): That

18.  def collectFirst[B](pf: PartialFunction[A, B]): Option[B]

    Finds the first element of the traversable or iterator for which the given partial function is defined, and applies the partial function to it.

    Finds the first element of the traversable or iterator for which the given partial function is defined, and applies the partial function to it.

    Note: may not terminate for infinite-sized collections.

    Note: might return different results for different runs, unless the underlying collection type is ordered.

    pf

      the partial function

    returns

      an option value containing pf applied to the first value for which it is defined, or `None` if none exists.

    Definition Classes
      TraversableOnce
    Example:

    1. `Seq("a", 1, 5L).collectFirst({ case x: Int => x*10 }) = Some(10)`

19.  def combinations(n: Int): Iterator[Repr]

    Iterates over combinations.

    Iterates over combinations. A _combination_ of length `n` is a subsequence of the original sequence, with the elements taken in order. Thus, `"xy"` and `"yy"` are both length-2 combinations of `"xyy"`, but `"yx"` is not. If there is more than one way to generate the same subsequence, only one will be returned.

    For example, `"xyyy"` has three different ways to generate `"xy"` depending on whether the first, second, or third `"y"` is selected. However, since all are identical, only one will be chosen. Which of the three will be taken is an implementation detail that is not defined.

    returns

      An Iterator which traverses the possible n-element combinations of this sequence.

    Definition Classes
      SeqLike
    Example:

    1. `"abbbc".combinations(2) = Iterator(ab, ac, bb, bc)`

20.  def contains[A1 >: A](elem: A1): Boolean

    Tests whether this sequence contains a given value as an element.

    Tests whether this sequence contains a given value as an element.

    Note: may not terminate for infinite-sized collections.

    elem

      the element to test.

    returns

      `true` if this sequence has an element that is equal (as determined by `==`) to `elem`, `false` otherwise.

    Definition Classes
      SeqLike
21.  def containsSlice[B](that: GenSeq[B]): Boolean

    Tests whether this sequence contains a given sequence as a slice.

    Tests whether this sequence contains a given sequence as a slice.

    Note: may not terminate for infinite-sized collections.

    that

      the sequence to test

    returns

      `true` if this sequence contains a slice with the same elements as `that`, otherwise `false`.

    Definition Classes
      SeqLike
22.  def copyToArray(xs: Array[A], start: Int, len: Int): Unit

    [use case] Copies the elements of this sequence to an array.

    [use case]

    Copies the elements of this sequence to an array. Fills the given array `xs` with at most `len` elements of this sequence, starting at position `start`. Copying will stop once either the end of the current sequence is reached, or the end of the target array is reached, or `len` elements have been copied.

    xs

      the array to fill.

    start

      the starting index.

    len

      the maximal number of elements to copy.

    Definition Classes
      IndexedSeqOptimized → IterableLike → TraversableLike → TraversableOnce → GenTraversableOnce
     Full Signature

    #### def copyToArray[B >: A](xs: Array[B], start: Int, len: Int): Unit

23.  def copyToArray(xs: Array[A]): Unit

    [use case] Copies the elements of this sequence to an array.

    [use case]

    Copies the elements of this sequence to an array. Fills the given array `xs` with values of this sequence. Copying will stop once either the end of the current sequence is reached, or the end of the target array is reached.

    xs

      the array to fill.

    Definition Classes
      TraversableOnce → GenTraversableOnce
     Full Signature

    #### def copyToArray[B >: A](xs: Array[B]): Unit

24.  def copyToArray(xs: Array[A], start: Int): Unit

    [use case] Copies the elements of this sequence to an array.

    [use case]

    Copies the elements of this sequence to an array. Fills the given array `xs` with values of this sequence, beginning at index `start`. Copying will stop once either the end of the current sequence is reached, or the end of the target array is reached.

    xs

      the array to fill.

    start

      the starting index.

    Definition Classes
      TraversableOnce → GenTraversableOnce
     Full Signature

    #### def copyToArray[B >: A](xs: Array[B], start: Int): Unit

25.  def copyToBuffer[B >: A](dest: Buffer[B]): Unit

    Copies all elements of this traversable or iterator to a buffer.

    Copies all elements of this traversable or iterator to a buffer.

    Note: will not terminate for infinite-sized collections.

    dest

      The buffer to which elements are copied.

    Definition Classes
      TraversableOnce
26.  def corresponds[B](that: GenSeq[B])(p: (A, B) ⇒ Boolean): Boolean

    Tests whether every element of this sequence relates to the corresponding element of another sequence by satisfying a test predicate.

    Tests whether every element of this sequence relates to the corresponding element of another sequence by satisfying a test predicate.

    B

      the type of the elements of `that`

    that

      the other sequence

    p

      the test predicate, which relates elements from both sequences

    returns

      `true` if both sequences have the same length and `p(x, y)` is `true` for all corresponding elements `x` of this sequence and `y` of `that`, otherwise `false`.

    Definition Classes
      SeqLike → GenSeqLike
27.  def count(p: (A) ⇒ Boolean): Int

    Counts the number of elements in the traversable or iterator which satisfy a predicate.

    Counts the number of elements in the traversable or iterator which satisfy a predicate.

    p

      the predicate used to test elements.

    returns

      the number of elements satisfying the predicate `p`.

    Definition Classes
      TraversableOnce → GenTraversableOnce
28.  def diff(that: Seq[A]): IndexedSeq[A]

    [use case] Computes the multiset difference between this sequence and another sequence.

    [use case]

    Computes the multiset difference between this sequence and another sequence.

    that

      the sequence of elements to remove

    returns

      a new sequence which contains all elements of this sequence except some of occurrences of elements that also appear in `that`. If an element value `x` appears n times in `that`, then the first n occurrences of `x` will not form part of the result, but any following occurrences will.

    Definition Classes
      SeqLike → GenSeqLike
     Full Signature

    #### def diff[B >: A](that: GenSeq[B]): Repr

29.  def distinct: Repr

    Builds a new sequence from this sequence without any duplicate elements.

    Builds a new sequence from this sequence without any duplicate elements.

    Note: will not terminate for infinite-sized collections.

    returns

      A new sequence which contains the first occurrence of every element of this sequence.

    Definition Classes
      SeqLike → GenSeqLike
30.  def drop(n: Int): Repr

    Selects all elements except first n ones.

    Selects all elements except first n ones.

    n

      the number of elements to drop from this sequence.

    returns

      a sequence consisting of all elements of this sequence except the first `n` ones, or else the empty sequence, if this sequence has less than `n` elements. If `n` is negative, don't drop any elements.

    Definition Classes
      IndexedSeqOptimized → IterableLike → TraversableLike → GenTraversableLike
31.  def dropRight(n: Int): Repr

    Selects all elements except last n ones.

    Selects all elements except last n ones.

    n

      The number of elements to take

    returns

      a sequence consisting of all elements of this sequence except the last `n` ones, or else the empty sequence, if this sequence has less than `n` elements.

    Definition Classes
      IndexedSeqOptimized → IterableLike
32.  def dropWhile(p: (A) ⇒ Boolean): Repr

    Drops longest prefix of elements that satisfy a predicate.

    Drops longest prefix of elements that satisfy a predicate.

    returns

      the longest suffix of this sequence whose first element does not satisfy the predicate `p`.

    Definition Classes
      IndexedSeqOptimized → TraversableLike → GenTraversableLike
33.  def endsWith[B](that: GenSeq[B]): Boolean

    Tests whether this sequence ends with the given sequence.

    Tests whether this sequence ends with the given sequence.

    that

      the sequence to test

    returns

      `true` if this sequence has `that` as a suffix, `false` otherwise.

    Definition Classes
      IndexedSeqOptimized → SeqLike → GenSeqLike
34.  def ensuring(cond: (IndexedSeqOptimized[A, Repr]) ⇒ Boolean, msg: ⇒ Any): IndexedSeqOptimized[A, Repr]
    Implicit
      This member is added by an implicit conversion from IndexedSeqOptimized[A, Repr] to Ensuring[IndexedSeqOptimized[A, Repr]] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
35.  def ensuring(cond: (IndexedSeqOptimized[A, Repr]) ⇒ Boolean): IndexedSeqOptimized[A, Repr]
    Implicit
      This member is added by an implicit conversion from IndexedSeqOptimized[A, Repr] to Ensuring[IndexedSeqOptimized[A, Repr]] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
36.  def ensuring(cond: Boolean, msg: ⇒ Any): IndexedSeqOptimized[A, Repr]
    Implicit
      This member is added by an implicit conversion from IndexedSeqOptimized[A, Repr] to Ensuring[IndexedSeqOptimized[A, Repr]] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
37.  def ensuring(cond: Boolean): IndexedSeqOptimized[A, Repr]
    Implicit
      This member is added by an implicit conversion from IndexedSeqOptimized[A, Repr] to Ensuring[IndexedSeqOptimized[A, Repr]] performed by method Ensuring in scala.Predef.
    Definition Classes
      Ensuring
38.  def equals(that: Any): Boolean

    The equals method for arbitrary sequences.

    The equals method for arbitrary sequences. Compares this sequence to some other object.

    that

      The object to compare the sequence to

    returns

      `true` if `that` is a sequence that has the same elements as this sequence in the same order, `false` otherwise

    Definition Classes
      GenSeqLike → Equals → Any
39.  def exists(p: (A) ⇒ Boolean): Boolean

    Tests whether a predicate holds for at least one element of this sequence.

    Tests whether a predicate holds for at least one element of this sequence.

    p

      the predicate used to test elements.

    returns

      `false` if this sequence is empty, otherwise `true` if the given predicate `p` holds for some of the elements of this sequence, otherwise `false`

    Definition Classes
      IndexedSeqOptimized → IterableLike → TraversableLike → TraversableOnce → GenTraversableOnce
40.  def filter(p: (A) ⇒ Boolean): Repr

    Selects all elements of this traversable collection which satisfy a predicate.

    Selects all elements of this traversable collection which satisfy a predicate.

    p

      the predicate used to test elements.

    returns

      a new traversable collection consisting of all elements of this traversable collection that satisfy the given predicate `p`. The order of the elements is preserved.

    Definition Classes
      TraversableLike → GenTraversableLike
41.  def filterNot(p: (A) ⇒ Boolean): Repr

    Selects all elements of this traversable collection which do not satisfy a predicate.

    Selects all elements of this traversable collection which do not satisfy a predicate.

    p

      the predicate used to test elements.

    returns

      a new traversable collection consisting of all elements of this traversable collection that do not satisfy the given predicate `p`. The order of the elements is preserved.

    Definition Classes
      TraversableLike → GenTraversableLike
42.  def find(p: (A) ⇒ Boolean): Option[A]

    Finds the first element of the sequence satisfying a predicate, if any.

    Finds the first element of the sequence satisfying a predicate, if any.

    p

      the predicate used to test elements.

    returns

      an option value containing the first element in the sequence that satisfies `p`, or `None` if none exists.

    Definition Classes
      IndexedSeqOptimized → IterableLike → TraversableLike → TraversableOnce → GenTraversableOnce
43.  def flatMap[B](f: (A) ⇒ GenTraversableOnce[B]): IndexedSeq[B]

    [use case] Builds a new collection by applying a function to all elements of this sequence and using the elements of the resulting collections.

    [use case]

    Builds a new collection by applying a function to all elements of this sequence and using the elements of the resulting collections.

    For example:

        def getWords(lines: Seq[String]): Seq[String] = lines flatMap (line => line split "\\W+")

    The type of the resulting collection is guided by the static type of sequence. This might cause unexpected results sometimes. For example:

        // lettersOf will return a Seq[Char] of likely repeated letters, instead of a Set
        def lettersOf(words: Seq[String]) = words flatMap (word => word.toSet)

        // lettersOf will return a Set[Char], not a Seq
        def lettersOf(words: Seq[String]) = words.toSet flatMap (word => word.toSeq)

        // xs will be an Iterable[Int]
        val xs = Map("a" -> List(11,111), "b" -> List(22,222)).flatMap(_._2)

        // ys will be a Map[Int, Int]
        val ys = Map("a" -> List(1 -> 11,1 -> 111), "b" -> List(2 -> 22,2 -> 222)).flatMap(_._2)

    B

      the element type of the returned collection.

    f

      the function to apply to each element.

    returns

      a new sequence resulting from applying the given collection-valued function `f` to each element of this sequence and concatenating the results.

    Definition Classes
      TraversableLike → GenTraversableLike → FilterMonadic
     Full Signature

    #### def flatMap[B, That](f: (A) ⇒ GenTraversableOnce[B])(implicit bf: CanBuildFrom[Repr, B, That]): That

44.  def fold[A1 >: A](z: A1)(op: (A1, A1) ⇒ A1): A1

    Folds the elements of this traversable or iterator using the specified associative binary operator.

    Folds the elements of this traversable or iterator using the specified associative binary operator.

    The order in which operations are performed on elements is unspecified and may be nondeterministic.

    Note: will not terminate for infinite-sized collections.

    A1

      a type parameter for the binary operator, a supertype of `A`.

    z

      a neutral element for the fold operation; may be added to the result an arbitrary number of times, and must not change the result (e.g., `Nil` for list concatenation, 0 for addition, or 1 for multiplication).

    op

      a binary operator that must be associative.

    returns

      the result of applying the fold operator `op` between all the elements and `z`, or `z` if this traversable or iterator is empty.

    Definition Classes
      TraversableOnce → GenTraversableOnce
45.  def foldLeft[B](z: B)(op: (B, A) ⇒ B): B

    Applies a binary operator to a start value and all elements of this sequence, going left to right.

    Applies a binary operator to a start value and all elements of this sequence, going left to right.

    B

      the result type of the binary operator.

    z

      the start value.

    op

      the binary operator.

    returns

      the result of inserting `op` between consecutive elements of this sequence, going left to right with the start value `z` on the left:

          op(...op(z, x_1), x_2, ..., x_n)

      where `x1, ..., xn` are the elements of this sequence. Returns `z` if this sequence is empty.

    Definition Classes
      IndexedSeqOptimized → TraversableOnce → GenTraversableOnce
46.  def foldRight[B](z: B)(op: (A, B) ⇒ B): B

    Applies a binary operator to all elements of this sequence and a start value, going right to left.

    Applies a binary operator to all elements of this sequence and a start value, going right to left.

    B

      the result type of the binary operator.

    z

      the start value.

    op

      the binary operator.

    returns

      the result of inserting `op` between consecutive elements of this sequence, going right to left with the start value `z` on the right:

          op(x_1, op(x_2, ... op(x_n, z)...))

      where `x1, ..., xn` are the elements of this sequence. Returns `z` if this sequence is empty.

    Definition Classes
      IndexedSeqOptimized → IterableLike → TraversableOnce → GenTraversableOnce
47.  def forall(p: (A) ⇒ Boolean): Boolean

    Tests whether a predicate holds for all elements of this sequence.

    Tests whether a predicate holds for all elements of this sequence.

    p

      the predicate used to test elements.

    returns

      `true` if this sequence is empty or the given predicate `p` holds for all elements of this sequence, otherwise `false`.

    Definition Classes
      IndexedSeqOptimized → IterableLike → TraversableLike → TraversableOnce → GenTraversableOnce
48.  def foreach(f: (A) ⇒ Unit): Unit

    [use case] Applies a function `f` to all elements of this sequence.

    [use case]

    Applies a function `f` to all elements of this sequence.

    Note: this method underlies the implementation of most other bulk operations. Subclasses should re-implement this method if a more efficient implementation exists.

    f

      the function that is applied for its side-effect to every element. The result of function `f` is discarded.

    Definition Classes
      IndexedSeqOptimized → IterableLike → TraversableLike → GenTraversableLike → TraversableOnce → GenTraversableOnce → FilterMonadic
     Full Signature

    #### def foreach[U](f: (A) ⇒ U): Unit

49.  def groupBy[K](f: (A) ⇒ K): immutable.Map[K, Repr]

    Partitions this traversable collection into a map of traversable collections according to some discriminator function.

    Partitions this traversable collection into a map of traversable collections according to some discriminator function.

    Note: this method is not re-implemented by views. This means when applied to a view it will always force the view and return a new traversable collection.

    K

      the type of keys returned by the discriminator function.

    f

      the discriminator function.

    returns

      A map from keys to traversable collections such that the following invariant holds:

          (xs groupBy f)(k) = xs filter (x => f(x) == k)

      That is, every key `k` is bound to a traversable collection of those elements `x` for which `f(x)` equals `k`.

    Definition Classes
      TraversableLike → GenTraversableLike
50.  def grouped(size: Int): Iterator[Repr]

    Partitions elements in fixed size iterable collections.

    Partitions elements in fixed size iterable collections.

    size

      the number of elements per group

    returns

      An iterator producing iterable collections of size `size`, except the last will be less than size `size` if the elements don't divide evenly.

    Definition Classes
      IterableLike
    See also

      scala.collection.Iterator, method `grouped`

51.  def hasDefiniteSize: Boolean

    Tests whether this traversable collection is known to have a finite size.

    Tests whether this traversable collection is known to have a finite size. All strict collections are known to have finite size. For a non-strict collection such as `Stream`, the predicate returns `true` if all elements have been computed. It returns `false` if the stream is not yet evaluated to the end. Non-empty Iterators usually return `false` even if they were created from a collection with a known finite size.

    Note: many collection methods will not work on collections of infinite sizes. The typical failure mode is an infinite loop. These methods always attempt a traversal without checking first that `hasDefiniteSize` returns `true`. However, checking `hasDefiniteSize` can provide an assurance that size is well-defined and non-termination is not a concern.

    returns

      `true` if this collection is known to have finite size, `false` otherwise.

    Definition Classes
      TraversableLike → TraversableOnce → GenTraversableOnce
52.  def hashCode(): Int

    Hashcodes for IndexedSeq produce a value from the hashcodes of all the elements of the sequence.

    Hashcodes for IndexedSeq produce a value from the hashcodes of all the elements of the sequence.

    returns

      the hash code value for this object.

    Definition Classes
      IndexedSeqLike → GenSeqLike → Any
53.  def head: A

    Selects the first element of this sequence.

    Selects the first element of this sequence.

    returns

      the first element of this sequence.

    Definition Classes
      IndexedSeqOptimized → IterableLike → TraversableLike → GenTraversableLike
    Exceptions thrown

      `NoSuchElementException` if the sequence is empty.

54.  def headOption: Option[A]

    Optionally selects the first element.

    Optionally selects the first element.

    Note: might return different results for different runs, unless the underlying collection type is ordered.

    returns

      the first element of this traversable collection if it is nonempty, `None` if it is empty.

    Definition Classes
      TraversableLike → GenTraversableLike
55.  def indexOf(elem: A, from: Int): Int

    [use case] Finds index of first occurrence of some value in this sequence after or at some start index.

    [use case]

    Finds index of first occurrence of some value in this sequence after or at some start index.

    elem

      the element value to search for.

    from

      the start index

    returns

      the index `>= from` of the first element of this sequence that is equal (as determined by `==`) to `elem`, or `-1`, if none exists.

    Definition Classes
      GenSeqLike
     Full Signature

    #### def indexOf[B >: A](elem: B, from: Int): Int

56.  def indexOf(elem: A): Int

    [use case] Finds index of first occurrence of some value in this sequence.

    [use case]

    Finds index of first occurrence of some value in this sequence.

    elem

      the element value to search for.

    returns

      the index of the first element of this sequence that is equal (as determined by `==`) to `elem`, or `-1`, if none exists.

    Definition Classes
      GenSeqLike
     Full Signature

    #### def indexOf[B >: A](elem: B): Int

57.  def indexOfSlice[B >: A](that: GenSeq[B], from: Int): Int

    Finds first index after or at a start index where this sequence contains a given sequence as a slice.

    Finds first index after or at a start index where this sequence contains a given sequence as a slice.

    Note: may not terminate for infinite-sized collections.

    that

      the sequence to test

    from

      the start index

    returns

      the first index `>= from` such that the elements of this sequence starting at this index match the elements of sequence `that`, or `-1` of no such subsequence exists.

    Definition Classes
      SeqLike
58.  def indexOfSlice[B >: A](that: GenSeq[B]): Int

    Finds first index where this sequence contains a given sequence as a slice.

    Finds first index where this sequence contains a given sequence as a slice.

    Note: may not terminate for infinite-sized collections.

    that

      the sequence to test

    returns

      the first index such that the elements of this sequence starting at this index match the elements of sequence `that`, or `-1` of no such subsequence exists.

    Definition Classes
      SeqLike
59.  def indexWhere(p: (A) ⇒ Boolean, from: Int): Int

    Finds index of the first element satisfying some predicate after or at some start index.

    Finds index of the first element satisfying some predicate after or at some start index.

    p

      the predicate used to test elements.

    from

      the start index

    returns

      the index `>= from` of the first element of this sequence that satisfies the predicate `p`, or `-1`, if none exists.

    Definition Classes
      IndexedSeqOptimized → SeqLike → GenSeqLike
60.  def indexWhere(p: (A) ⇒ Boolean): Int

    Finds index of first element satisfying some predicate.

    Finds index of first element satisfying some predicate.

    Note: may not terminate for infinite-sized collections.

    p

      the predicate used to test elements.

    returns

      the index of the first element of this general sequence that satisfies the predicate `p`, or `-1`, if none exists.

    Definition Classes
      GenSeqLike
61.  def indices: immutable.Range

    Produces the range of all indices of this sequence.

    Produces the range of all indices of this sequence.

    returns

      a `Range` value from `0` to one less than the length of this sequence.

    Definition Classes
      SeqLike
62.  def init: Repr

    Selects all elements except the last.

    Selects all elements except the last.

    returns

      a sequence consisting of all elements of this sequence except the last one.

    Definition Classes
      IndexedSeqOptimized → TraversableLike → GenTraversableLike
    Exceptions thrown

      `UnsupportedOperationException` if the sequence is empty.

63.  def inits: Iterator[Repr]

    Iterates over the inits of this traversable collection.

    Iterates over the inits of this traversable collection. The first value will be this traversable collection and the final one will be an empty traversable collection, with the intervening values the results of successive applications of `init`.

    returns

      an iterator over all the inits of this traversable collection

    Definition Classes
      TraversableLike
    Example:

    1. `List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)`

64.  def intersect(that: Seq[A]): IndexedSeq[A]

    [use case] Computes the multiset intersection between this sequence and another sequence.

    [use case]

    Computes the multiset intersection between this sequence and another sequence.

    that

      the sequence of elements to intersect with.

    returns

      a new sequence which contains all elements of this sequence which also appear in `that`. If an element value `x` appears n times in `that`, then the first n occurrences of `x` will be retained in the result, but any following occurrences will be omitted.

    Definition Classes
      SeqLike → GenSeqLike
     Full Signature

    #### def intersect[B >: A](that: GenSeq[B]): Repr

65.  def isDefinedAt(idx: Int): Boolean

    Tests whether this general sequence contains given index.

    Tests whether this general sequence contains given index.

    The implementations of methods `apply` and `isDefinedAt` turn a `Seq[A]` into a `PartialFunction[Int, A]`.

    idx

      the index to test

    returns

      `true` if this general sequence contains an element at position `idx`, `false` otherwise.

    Definition Classes
      GenSeqLike
66.  def isEmpty: Boolean

    Tests whether this sequence is empty.

    Tests whether this sequence is empty.

    returns

      `true` if the sequence contain no elements, `false` otherwise.

    Definition Classes
      IndexedSeqOptimized → SeqLike → IterableLike → TraversableLike → TraversableOnce → GenTraversableOnce
67.  final def isInstanceOf[T0]: Boolean

    Test whether the dynamic type of the receiver object is `T0`.

    Test whether the dynamic type of the receiver object is `T0`.

    Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression `1.isInstanceOf[String]` will return `false`, while the expression `List(1).isInstanceOf[List[String]]` will return `true`. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.

    returns

      `true` if the receiver object is an instance of erasure of type `T0`; `false` otherwise.

    Definition Classes
      Any
68.  final def isTraversableAgain: Boolean

    Tests whether this traversable collection can be repeatedly traversed.

    Tests whether this traversable collection can be repeatedly traversed.

    returns

      `true`

    Definition Classes
      TraversableLike → GenTraversableLike → GenTraversableOnce
69.  def iterator: Iterator[A]

    Creates a new iterator over all elements contained in this iterable object.

    Creates a new iterator over all elements contained in this iterable object.

    returns

      the new iterator

    Definition Classes
      IndexedSeqLike → IterableLike → GenIterableLike
70.  def last: A

    Selects the last element.

    Selects the last element.

    returns

      The last element of this sequence.

    Definition Classes
      IndexedSeqOptimized → TraversableLike → GenTraversableLike
    Exceptions thrown

      `NoSuchElementException` If the sequence is empty.

71.  def lastIndexOf(elem: A, end: Int): Int

    [use case] Finds index of last occurrence of some value in this sequence before or at a given end index.

    [use case]

    Finds index of last occurrence of some value in this sequence before or at a given end index.

    elem

      the element value to search for.

    end

      the end index.

    returns

      the index `<= end` of the last element of this sequence that is equal (as determined by `==`) to `elem`, or `-1`, if none exists.

    Definition Classes
      GenSeqLike
     Full Signature

    #### def lastIndexOf[B >: A](elem: B, end: Int): Int

72.  def lastIndexOf(elem: A): Int

    [use case] Finds index of last occurrence of some value in this sequence.

    [use case]

    Finds index of last occurrence of some value in this sequence.

    elem

      the element value to search for.

    returns

      the index of the last element of this sequence that is equal (as determined by `==`) to `elem`, or `-1`, if none exists.

    Definition Classes
      GenSeqLike
     Full Signature

    #### def lastIndexOf[B >: A](elem: B): Int

73.  def lastIndexOfSlice[B >: A](that: GenSeq[B], end: Int): Int

    Finds last index before or at a given end index where this sequence contains a given sequence as a slice.

    Finds last index before or at a given end index where this sequence contains a given sequence as a slice.

    that

      the sequence to test

    end

      the end index

    returns

      the last index `<= end` such that the elements of this sequence starting at this index match the elements of sequence `that`, or `-1` of no such subsequence exists.

    Definition Classes
      SeqLike
74.  def lastIndexOfSlice[B >: A](that: GenSeq[B]): Int

    Finds last index where this sequence contains a given sequence as a slice.

    Finds last index where this sequence contains a given sequence as a slice.

    Note: will not terminate for infinite-sized collections.

    that

      the sequence to test

    returns

      the last index such that the elements of this sequence starting a this index match the elements of sequence `that`, or `-1` of no such subsequence exists.

    Definition Classes
      SeqLike
75.  def lastIndexWhere(p: (A) ⇒ Boolean, end: Int): Int

    Finds index of last element satisfying some predicate before or at given end index.

    Finds index of last element satisfying some predicate before or at given end index.

    p

      the predicate used to test elements.

    returns

      the index `<= end` of the last element of this sequence that satisfies the predicate `p`, or `-1`, if none exists.

    Definition Classes
      IndexedSeqOptimized → SeqLike → GenSeqLike
76.  def lastIndexWhere(p: (A) ⇒ Boolean): Int

    Finds index of last element satisfying some predicate.

    Finds index of last element satisfying some predicate.

    Note: will not terminate for infinite-sized collections.

    p

      the predicate used to test elements.

    returns

      the index of the last element of this general sequence that satisfies the predicate `p`, or `-1`, if none exists.

    Definition Classes
      GenSeqLike
77.  def lastOption: Option[A]

    Optionally selects the last element.

    Optionally selects the last element.

    Note: might return different results for different runs, unless the underlying collection type is ordered.

    returns

      the last element of this traversable collection$ if it is nonempty, `None` if it is empty.

    Definition Classes
      TraversableLike → GenTraversableLike
78.  def lengthCompare(len: Int): Int

    Compares the length of this sequence to a test value.

    Compares the length of this sequence to a test value.

    len

      the test value that gets compared with the length.

    returns

      A value `x` where

          x <  0       if this.length <  len
          x == 0       if this.length == len
          x >  0       if this.length >  len

      The method as implemented here does not call `length` directly; its running time is `O(length min len)` instead of `O(length)`. The method should be overwritten if computing `length` is cheap.

    Definition Classes
      IndexedSeqOptimized → SeqLike
79.  def map[B](f: (A) ⇒ B): IndexedSeq[B]

    [use case] Builds a new collection by applying a function to all elements of this sequence.

    [use case]

    Builds a new collection by applying a function to all elements of this sequence.

    B

      the element type of the returned collection.

    f

      the function to apply to each element.

    returns

      a new sequence resulting from applying the given function `f` to each element of this sequence and collecting the results.

    Definition Classes
      TraversableLike → GenTraversableLike → FilterMonadic
     Full Signature

    #### def map[B, That](f: (A) ⇒ B)(implicit bf: CanBuildFrom[Repr, B, That]): That

80.  def max: A

    [use case] Finds the largest element.

    [use case]

    Finds the largest element.

    returns

      the largest element of this sequence.

    Definition Classes
      TraversableOnce → GenTraversableOnce
     Full Signature

    #### def max[B >: A](implicit cmp: Ordering[B]): A

    Exceptions thrown

      `UnsupportedOperationException` if this sequence is empty.

81.  def maxBy[B](f: (A) ⇒ B): A

    [use case] Finds the first element which yields the largest value measured by function f.

    [use case]

    Finds the first element which yields the largest value measured by function f.

    B

      The result type of the function f.

    f

      The measuring function.

    returns

      the first element of this sequence with the largest value measured by function f.

    Definition Classes
      TraversableOnce → GenTraversableOnce
     Full Signature

    #### def maxBy[B](f: (A) ⇒ B)(implicit cmp: Ordering[B]): A

    Exceptions thrown

      `UnsupportedOperationException` if this sequence is empty.

82.  def min: A

    [use case] Finds the smallest element.

    [use case]

    Finds the smallest element.

    returns

      the smallest element of this sequence

    Definition Classes
      TraversableOnce → GenTraversableOnce
     Full Signature

    #### def min[B >: A](implicit cmp: Ordering[B]): A

    Exceptions thrown

      `UnsupportedOperationException` if this sequence is empty.

83.  def minBy[B](f: (A) ⇒ B): A

    [use case] Finds the first element which yields the smallest value measured by function f.

    [use case]

    Finds the first element which yields the smallest value measured by function f.

    B

      The result type of the function f.

    f

      The measuring function.

    returns

      the first element of this sequence with the smallest value measured by function f.

    Definition Classes
      TraversableOnce → GenTraversableOnce
     Full Signature

    #### def minBy[B](f: (A) ⇒ B)(implicit cmp: Ordering[B]): A

    Exceptions thrown

      `UnsupportedOperationException` if this sequence is empty.

84.  def mkString: String

    Displays all elements of this traversable or iterator in a string.

    Displays all elements of this traversable or iterator in a string.

    returns

      a string representation of this traversable or iterator. In the resulting string the string representations (w.r.t. the method `toString`) of all elements of this traversable or iterator follow each other without any separator string.

    Definition Classes
      TraversableOnce → GenTraversableOnce
85.  def mkString(sep: String): String

    Displays all elements of this traversable or iterator in a string using a separator string.

    Displays all elements of this traversable or iterator in a string using a separator string.

    sep

      the separator string.

    returns

      a string representation of this traversable or iterator. In the resulting string the string representations (w.r.t. the method `toString`) of all elements of this traversable or iterator are separated by the string `sep`.

    Definition Classes
      TraversableOnce → GenTraversableOnce
    Example:

    1. `List(1, 2, 3).mkString("|") = "1|2|3"`

86.  def mkString(start: String, sep: String, end: String): String

    Displays all elements of this traversable or iterator in a string using start, end, and separator strings.

    Displays all elements of this traversable or iterator in a string using start, end, and separator strings.

    start

      the starting string.

    sep

      the separator string.

    end

      the ending string.

    returns

      a string representation of this traversable or iterator. The resulting string begins with the string `start` and ends with the string `end`. Inside, the string representations (w.r.t. the method `toString`) of all elements of this traversable or iterator are separated by the string `sep`.

    Definition Classes
      TraversableOnce → GenTraversableOnce
    Example:

    1. `List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"`

87.  def nonEmpty: Boolean

    Tests whether the traversable or iterator is not empty.

    Tests whether the traversable or iterator is not empty.

    returns

      `true` if the traversable or iterator contains at least one element, `false` otherwise.

    Definition Classes
      TraversableOnce → GenTraversableOnce
88.  def padTo(len: Int, elem: A): IndexedSeq[A]

    [use case] A copy of this sequence with an element value appended until a given target length is reached.

    [use case]

    A copy of this sequence with an element value appended until a given target length is reached.

    len

      the target length

    elem

      the padding value

    returns

      a new sequence consisting of all elements of this sequence followed by the minimal number of occurrences of `elem` so that the resulting sequence has a length of at least `len`.

    Definition Classes
      SeqLike → GenSeqLike
     Full Signature

    #### def padTo[B >: A, That](len: Int, elem: B)(implicit bf: CanBuildFrom[Repr, B, That]): That

89.  def par: ParSeq[A]

    Returns a parallel implementation of this collection.

    Returns a parallel implementation of this collection.

    For most collection types, this method creates a new parallel collection by copying all the elements. For these collection, `par` takes linear time. Mutable collections in this category do not produce a mutable parallel collection that has the same underlying dataset, so changes in one collection will not be reflected in the other one.

    Specific collections (e.g. `ParArray` or `mutable.ParHashMap`) override this default behaviour by creating a parallel collection which shares the same underlying dataset. For these collections, `par` takes constant or sublinear time.

    All parallel collections return a reference to themselves.

    returns

      a parallel implementation of this collection

    Definition Classes
      Parallelizable
90.  def parCombiner: Combiner[A, ParSeq[A]]

    The default `par` implementation uses the combiner provided by this method to create a new parallel collection.

    The default `par` implementation uses the combiner provided by this method to create a new parallel collection.

    returns

      a combiner for the parallel collection of type `ParRepr`

    Attributes
      protected[this]
    Definition Classes
      SeqLike → TraversableLike → Parallelizable
91.  def partition(p: (A) ⇒ Boolean): (Repr, Repr)

    Partitions this traversable collection in two traversable collections according to a predicate.

    Partitions this traversable collection in two traversable collections according to a predicate.

    p

      the predicate on which to partition.

    returns

      a pair of traversable collections: the first traversable collection consists of all elements that satisfy the predicate `p` and the second traversable collection consists of all elements that don't. The relative order of the elements in the resulting traversable collections is the same as in the original traversable collection.

    Definition Classes
      TraversableLike → GenTraversableLike
92.  def patch(from: Int, that: GenSeq[A], replaced: Int): IndexedSeq[A]

    [use case] Produces a new sequence where a slice of elements in this sequence is replaced by another sequence.

    [use case]

    Produces a new sequence where a slice of elements in this sequence is replaced by another sequence.

    from

      the index of the first replaced element

    replaced

      the number of elements to drop in the original sequence

    returns

      a new sequence consisting of all elements of this sequence except that `replaced` elements starting from `from` are replaced by `patch`.

    Definition Classes
      SeqLike → GenSeqLike
     Full Signature

    #### def patch[B >: A, That](from: Int, patch: GenSeq[B], replaced: Int)(implicit bf: CanBuildFrom[Repr, B, That]): That

93.  def permutations: Iterator[Repr]

    Iterates over distinct permutations.

    Iterates over distinct permutations.

    returns

      An Iterator which traverses the distinct permutations of this sequence.

    Definition Classes
      SeqLike
    Example:

    1. `"abb".permutations = Iterator(abb, bab, bba)`

94.  def prefixLength(p: (A) ⇒ Boolean): Int

    Returns the length of the longest prefix whose elements all satisfy some predicate.

    Returns the length of the longest prefix whose elements all satisfy some predicate.

    Note: may not terminate for infinite-sized collections.

    p

      the predicate used to test elements.

    returns

      the length of the longest prefix of this general sequence such that every element of the segment satisfies the predicate `p`.

    Definition Classes
      GenSeqLike
95.  def product: A

    [use case] Multiplies up the elements of this collection.

    [use case]

    Multiplies up the elements of this collection.

    returns

      the product of all elements in this sequence of numbers of type `Int`. Instead of `Int`, any other type `T` with an implicit `Numeric[T]` implementation can be used as element type of the sequence and as result type of `product`. Examples of such types are: `Long`, `Float`, `Double`, `BigInt`.

    Definition Classes
      TraversableOnce → GenTraversableOnce
     Full Signature

    #### def product[B >: A](implicit num: Numeric[B]): B

96.  def reduce[A1 >: A](op: (A1, A1) ⇒ A1): A1

    Reduces the elements of this traversable or iterator using the specified associative binary operator.

    Reduces the elements of this traversable or iterator using the specified associative binary operator.

    The order in which operations are performed on elements is unspecified and may be nondeterministic.

    A1

      A type parameter for the binary operator, a supertype of `A`.

    op

      A binary operator that must be associative.

    returns

      The result of applying reduce operator `op` between all the elements if the traversable or iterator is nonempty.

    Definition Classes
      TraversableOnce → GenTraversableOnce
    Exceptions thrown

      `UnsupportedOperationException` if this traversable or iterator is empty.

97.  def reduceLeft[B >: A](op: (B, A) ⇒ B): B

    Applies a binary operator to all elements of this sequence, going left to right.

    Applies a binary operator to all elements of this sequence, going left to right.

    B

      the result type of the binary operator.

    op

      the binary operator.

    returns

      the result of inserting `op` between consecutive elements of this sequence, going left to right:

          op( op( ... op(x_1, x_2) ..., x_{n-1}), x_n)

      where `x1, ..., xn` are the elements of this sequence.

    Definition Classes
      IndexedSeqOptimized → TraversableOnce
    Exceptions thrown

      `UnsupportedOperationException` if this sequence is empty.

98.  def reduceLeftOption[B >: A](op: (B, A) ⇒ B): Option[B]

    Optionally applies a binary operator to all elements of this traversable or iterator, going left to right.

    Optionally applies a binary operator to all elements of this traversable or iterator, going left to right.

    Note: will not terminate for infinite-sized collections.

    Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

    B

      the result type of the binary operator.

    op

      the binary operator.

    returns

      an option value containing the result of `reduceLeft(op)` if this traversable or iterator is nonempty, `None` otherwise.

    Definition Classes
      TraversableOnce → GenTraversableOnce
99.  def reduceOption[A1 >: A](op: (A1, A1) ⇒ A1): Option[A1]

    Reduces the elements of this traversable or iterator, if any, using the specified associative binary operator.

    Reduces the elements of this traversable or iterator, if any, using the specified associative binary operator.

    The order in which operations are performed on elements is unspecified and may be nondeterministic.

    A1

      A type parameter for the binary operator, a supertype of `A`.

    op

      A binary operator that must be associative.

    returns

      An option value containing result of applying reduce operator `op` between all the elements if the collection is nonempty, and `None` otherwise.

    Definition Classes
      TraversableOnce → GenTraversableOnce
100.  def reduceRight[B >: A](op: (A, B) ⇒ B): B

     Applies a binary operator to all elements of this sequence, going right to left.

     Applies a binary operator to all elements of this sequence, going right to left.

     B

       the result type of the binary operator.

     op

       the binary operator.

     returns

       the result of inserting `op` between consecutive elements of this sequence, going right to left:

           op(x_1, op(x_2, ..., op(x_{n-1}, x_n)...))

       where `x1, ..., xn` are the elements of this sequence.

     Definition Classes
       IndexedSeqOptimized → IterableLike → TraversableOnce → GenTraversableOnce
     Exceptions thrown

       `UnsupportedOperationException` if this sequence is empty.

101.  def reduceRightOption[B >: A](op: (A, B) ⇒ B): Option[B]

     Optionally applies a binary operator to all elements of this traversable or iterator, going right to left.

     Optionally applies a binary operator to all elements of this traversable or iterator, going right to left.

     Note: will not terminate for infinite-sized collections.

     Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

     B

       the result type of the binary operator.

     op

       the binary operator.

     returns

       an option value containing the result of `reduceRight(op)` if this traversable or iterator is nonempty, `None` otherwise.

     Definition Classes
       TraversableOnce → GenTraversableOnce
102.  def repr: Repr

     The collection of type traversable collection underlying this `TraversableLike` object.

     The collection of type traversable collection underlying this `TraversableLike` object. By default this is implemented as the `TraversableLike` object itself, but this can be overridden.

     Definition Classes
       TraversableLike → GenTraversableLike
103.  def reverse: Repr

     Returns new sequence with elements in reversed order.

     Returns new sequence with elements in reversed order.

     returns

       A new sequence with all elements of this sequence in reversed order.

     Definition Classes
       IndexedSeqOptimized → SeqLike → GenSeqLike
104.  def reverseIterator: Iterator[A]

     An iterator yielding elements in reversed order.

     An iterator yielding elements in reversed order.

     Note: `xs.reverseIterator` is the same as `xs.reverse.iterator` but might be more efficient.

     returns

       an iterator yielding the elements of this sequence in reversed order

     Definition Classes
       IndexedSeqOptimized → SeqLike
105.  def reverseMap[B](f: (A) ⇒ B): IndexedSeq[B]

     [use case] Builds a new collection by applying a function to all elements of this sequence and collecting the results in reversed order.

     [use case]

     Builds a new collection by applying a function to all elements of this sequence and collecting the results in reversed order.

     Note: `xs.reverseMap(f)` is the same as `xs.reverse.map(f)` but might be more efficient.

     B

       the element type of the returned collection.

     f

       the function to apply to each element.

     returns

       a new sequence resulting from applying the given function `f` to each element of this sequence and collecting the results in reversed order.

     Definition Classes
       SeqLike → GenSeqLike
      Full Signature

     #### def reverseMap[B, That](f: (A) ⇒ B)(implicit bf: CanBuildFrom[Repr, B, That]): That

106.  def reversed: List[A]
     Attributes
       protected[this]
     Definition Classes
       TraversableOnce
107.  def sameElements(that: GenIterable[A]): Boolean

     [use case] Checks if the other iterable collection contains the same elements in the same order as this sequence.

     [use case]

     Checks if the other iterable collection contains the same elements in the same order as this sequence.

     that

       the collection to compare with.

     returns

       `true`, if both collections contain the same elements in the same order, `false` otherwise.

     Definition Classes
       IndexedSeqOptimized → IterableLike → GenIterableLike
      Full Signature

     #### def sameElements[B >: A](that: GenIterable[B]): Boolean

108.  def scan[B >: A, That](z: B)(op: (B, B) ⇒ B)(implicit cbf: CanBuildFrom[Repr, B, That]): That

     Computes a prefix scan of the elements of the collection.

     Computes a prefix scan of the elements of the collection.

     Note: The neutral element `z` may be applied more than once.

     B

       element type of the resulting collection

     That

       type of the resulting collection

     z

       neutral element for the operator `op`

     op

       the associative operator for the scan

     cbf

       combiner factory which provides a combiner

     returns

       a new traversable collection containing the prefix scan of the elements in this traversable collection

     Definition Classes
       TraversableLike → GenTraversableLike
109.  def scanLeft[B, That](z: B)(op: (B, A) ⇒ B)(implicit bf: CanBuildFrom[Repr, B, That]): That

     Produces a collection containing cumulative results of applying the operator going left to right.

     Produces a collection containing cumulative results of applying the operator going left to right.

     Note: will not terminate for infinite-sized collections.

     Note: might return different results for different runs, unless the underlying collection type is ordered.

     B

       the type of the elements in the resulting collection

     That

       the actual type of the resulting collection

     z

       the initial value

     op

       the binary operator applied to the intermediate result and the element

     bf

       an implicit value of class `CanBuildFrom` which determines the result class `That` from the current representation type `Repr` and the new element type `B`.

     returns

       collection with intermediate results

     Definition Classes
       TraversableLike → GenTraversableLike
110.  def scanRight[B, That](z: B)(op: (A, B) ⇒ B)(implicit bf: CanBuildFrom[Repr, B, That]): That

     Produces a collection containing cumulative results of applying the operator going right to left.

     Produces a collection containing cumulative results of applying the operator going right to left. The head of the collection is the last cumulative result.

     Note: will not terminate for infinite-sized collections.

     Note: might return different results for different runs, unless the underlying collection type is ordered.

     Example:

         List(1, 2, 3, 4).scanRight(0)(_ + _) == List(10, 9, 7, 4, 0)

     B

       the type of the elements in the resulting collection

     That

       the actual type of the resulting collection

     z

       the initial value

     op

       the binary operator applied to the intermediate result and the element

     bf

       an implicit value of class `CanBuildFrom` which determines the result class `That` from the current representation type `Repr` and the new element type `B`.

     returns

       collection with intermediate results

     Definition Classes
       TraversableLike → GenTraversableLike
     Annotations
       @migration
     Migration

       (Changed in version 2.9.0) The behavior of `scanRight` has changed. The previous behavior can be reproduced with scanRight.reverse.

111.  def segmentLength(p: (A) ⇒ Boolean, from: Int): Int

     Computes length of longest segment whose elements all satisfy some predicate.

     Computes length of longest segment whose elements all satisfy some predicate.

     p

       the predicate used to test elements.

     from

       the index where the search starts.

     returns

       the length of the longest segment of this sequence starting from index `from` such that every element of the segment satisfies the predicate `p`.

     Definition Classes
       IndexedSeqOptimized → SeqLike → GenSeqLike
112.  def size: Int

     The size of this sequence, equivalent to `length`.

     The size of this sequence, equivalent to `length`.

     Note: will not terminate for infinite-sized collections.

     returns

       the number of elements in this sequence.

     Definition Classes
       SeqLike → GenTraversableLike → TraversableOnce → GenTraversableOnce
113.  def sizeHintIfCheap: Int

     The size of this sequence, if it can be cheaply computed

     The size of this sequence, if it can be cheaply computed

     returns

       the number of elements in this sequence, or -1 if the size cannot be determined cheaply

     Attributes
       protected[collection]
     Definition Classes
       IndexedSeqLike → GenTraversableOnce
114.  def slice(from: Int, until: Int): Repr

     Selects an interval of elements.

     Selects an interval of elements. The returned collection is made up of all elements `x` which satisfy the invariant:

         from <= indexOf(x) < until

     returns

       a sequence containing the elements greater than or equal to index `from` extending up to (but not including) index `until` of this sequence.

     Definition Classes
       IndexedSeqOptimized → IterableLike → TraversableLike → GenTraversableLike
115.  def sliding(size: Int, step: Int): Iterator[Repr]

     Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)

     Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)

     size

       the number of elements per group

     step

       the distance between the first elements of successive groups

     returns

       An iterator producing iterable collections of size `size`, except the last element (which may be the only element) will be truncated if there are fewer than `size` elements remaining to be grouped.

     Definition Classes
       IterableLike
     See also

       scala.collection.Iterator, method `sliding`

116.  def sliding(size: Int): Iterator[Repr]

     Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in `grouped`.) The "sliding window" step is set to one.

     Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in `grouped`.) The "sliding window" step is set to one.

     size

       the number of elements per group

     returns

       An iterator producing iterable collections of size `size`, except the last element (which may be the only element) will be truncated if there are fewer than `size` elements remaining to be grouped.

     Definition Classes
       IterableLike
     See also

       scala.collection.Iterator, method `sliding`

117.  def sortBy[B](f: (A) ⇒ B)(implicit ord: math.Ordering[B]): Repr

     Sorts this `Seq` according to the Ordering which results from transforming an implicitly given Ordering with a transformation function.

     Sorts this `Seq` according to the Ordering which results from transforming an implicitly given Ordering with a transformation function.

     B

       the target type of the transformation `f`, and the type where the ordering `ord` is defined.

     f

       the transformation function mapping elements to some other domain `B`.

     ord

       the ordering assumed on domain `B`.

     returns

       a sequence consisting of the elements of this sequence sorted according to the ordering where `x < y` if `ord.lt(f(x), f(y))`.

     Definition Classes
       SeqLike
     Example:

     1.     val words = "The quick brown fox jumped over the lazy dog".split(' ')
            // this works because scala.Ordering will implicitly provide an Ordering[Tuple2[Int, Char]]
            words.sortBy(x => (x.length, x.head))
            res0: Array[String] = Array(The, dog, fox, the, lazy, over, brown, quick, jumped)

     See also

       scala.math.Ordering Note: will not terminate for infinite-sized collections.

118.  def sortWith(lt: (A, A) ⇒ Boolean): Repr

     Sorts this sequence according to a comparison function.

     Sorts this sequence according to a comparison function.

     Note: will not terminate for infinite-sized collections.

     The sort is stable. That is, elements that are equal (as determined by `lt`) appear in the same order in the sorted sequence as in the original.

     lt

       the comparison function which tests whether its first argument precedes its second argument in the desired ordering.

     returns

       a sequence consisting of the elements of this sequence sorted according to the comparison function `lt`.

     Definition Classes
       SeqLike
     Example:

     1.     List("Steve", "Tom", "John", "Bob").sortWith(_.compareTo(_) < 0) =
            List("Bob", "John", "Steve", "Tom")

119.  def sorted[B >: A](implicit ord: math.Ordering[B]): Repr

     Sorts this sequence according to an Ordering.

     Sorts this sequence according to an Ordering.

     The sort is stable. That is, elements that are equal (as determined by `lt`) appear in the same order in the sorted sequence as in the original.

     ord

       the ordering to be used to compare elements.

     returns

       a sequence consisting of the elements of this sequence sorted according to the ordering `ord`.

     Definition Classes
       SeqLike
     See also

       scala.math.Ordering

120.  def span(p: (A) ⇒ Boolean): (Repr, Repr)

     Splits this sequence into a prefix/suffix pair according to a predicate.

     Splits this sequence into a prefix/suffix pair according to a predicate.

     Note: `c span p` is equivalent to (but possibly more efficient than) `(c takeWhile p, c dropWhile p)`, provided the evaluation of the predicate `p` does not cause any side-effects.

     returns

       a pair consisting of the longest prefix of this sequence whose elements all satisfy `p`, and the rest of this sequence.

     Definition Classes
       IndexedSeqOptimized → TraversableLike → GenTraversableLike
121.  def splitAt(n: Int): (Repr, Repr)

     Splits this sequence into two at a given position.

     Splits this sequence into two at a given position. Note: `c splitAt n` is equivalent to (but possibly more efficient than) `(c take n, c drop n)`.

     n

       the position at which to split.

     returns

       a pair of sequences consisting of the first `n` elements of this sequence, and the other elements.

     Definition Classes
       IndexedSeqOptimized → TraversableLike → GenTraversableLike
122.  def startsWith[B](that: GenSeq[B], offset: Int): Boolean

     Tests whether this sequence contains the given sequence at a given index.

     Tests whether this sequence contains the given sequence at a given index.

     Note: If the both the receiver object `this` and the argument `that` are infinite sequences this method may not terminate.

     that

       the sequence to test

     offset

       the index where the sequence is searched.

     returns

       `true` if the sequence `that` is contained in this sequence at index `offset`, otherwise `false`.

     Definition Classes
       IndexedSeqOptimized → SeqLike → GenSeqLike
123.  def startsWith[B](that: GenSeq[B]): Boolean

     Tests whether this general sequence starts with the given sequence.

     Tests whether this general sequence starts with the given sequence.

     that

       the sequence to test

     returns

       `true` if this collection has `that` as a prefix, `false` otherwise.

     Definition Classes
       GenSeqLike
124.  def stringPrefix: String

     Defines the prefix of this object's `toString` representation.

     Defines the prefix of this object's `toString` representation.

     returns

       a string representation which starts the result of `toString` applied to this traversable collection. By default the string prefix is the simple name of the collection class traversable collection.

     Definition Classes
       TraversableLike → GenTraversableLike
125.  def sum: A

     [use case] Sums up the elements of this collection.

     [use case]

     Sums up the elements of this collection.

     returns

       the sum of all elements in this sequence of numbers of type `Int`. Instead of `Int`, any other type `T` with an implicit `Numeric[T]` implementation can be used as element type of the sequence and as result type of `sum`. Examples of such types are: `Long`, `Float`, `Double`, `BigInt`.

     Definition Classes
       TraversableOnce → GenTraversableOnce
      Full Signature

     #### def sum[B >: A](implicit num: Numeric[B]): B

126.  def tail: Repr

     Selects all elements except the first.

     Selects all elements except the first.

     returns

       a sequence consisting of all elements of this sequence except the first one.

     Definition Classes
       IndexedSeqOptimized → TraversableLike → GenTraversableLike
     Exceptions thrown

       `java.lang.UnsupportedOperationException` if the sequence is empty.

127.  def tails: Iterator[Repr]

     Iterates over the tails of this traversable collection.

     Iterates over the tails of this traversable collection. The first value will be this traversable collection and the final one will be an empty traversable collection, with the intervening values the results of successive applications of `tail`.

     returns

       an iterator over all the tails of this traversable collection

     Definition Classes
       TraversableLike
     Example:

     1. `List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)`

128.  def take(n: Int): Repr

     Selects first n elements.

     Selects first n elements.

     n

       the number of elements to take from this sequence.

     returns

       a sequence consisting only of the first `n` elements of this sequence, or else the whole sequence, if it has less than `n` elements. If `n` is negative, returns an empty sequence.

     Definition Classes
       IndexedSeqOptimized → IterableLike → TraversableLike → GenTraversableLike
129.  def takeRight(n: Int): Repr

     Selects last n elements.

     Selects last n elements.

     n

       the number of elements to take

     returns

       a sequence consisting only of the last `n` elements of this sequence, or else the whole sequence, if it has less than `n` elements.

     Definition Classes
       IndexedSeqOptimized → IterableLike
130.  def takeWhile(p: (A) ⇒ Boolean): Repr

     Takes longest prefix of elements that satisfy a predicate.

     Takes longest prefix of elements that satisfy a predicate.

     returns

       the longest prefix of this sequence whose elements all satisfy the predicate `p`.

     Definition Classes
       IndexedSeqOptimized → IterableLike → TraversableLike → GenTraversableLike
131.  def thisCollection: IndexedSeq[A]

     The underlying collection seen as an instance of `IndexedSeq`.

     The underlying collection seen as an instance of `IndexedSeq`. By default this is implemented as the current collection object itself, but this can be overridden.

     Attributes
       protected[this]
     Definition Classes
       IndexedSeqLike → SeqLike → IterableLike → TraversableLike
132.  def to[Col[_]]: Col[A]

     [use case] Converts this sequence into another by copying all elements.

     [use case]

     Converts this sequence into another by copying all elements.

     Col

       The collection type to build.

     returns

       a new collection containing all elements of this sequence.

     Definition Classes
       TraversableLike → TraversableOnce → GenTraversableOnce
      Full Signature

     #### def to[Col[_]](implicit cbf: CanBuildFrom[Nothing, A, Col[A]]): Col[A]

133.  def toArray: Array[A]

     [use case] Converts this sequence to an array.

     [use case]

     Converts this sequence to an array.

     returns

       an array containing all elements of this sequence. An `ClassTag` must be available for the element type of this sequence.

     Definition Classes
       TraversableOnce → GenTraversableOnce
      Full Signature

     #### def toArray[B >: A](implicit arg0: ClassTag[B]): Array[B]

134.  def toBuffer[A1 >: A]: Buffer[A1]

     Uses the contents of this sequence to create a new mutable buffer.

     Uses the contents of this sequence to create a new mutable buffer.

     returns

       a buffer containing all elements of this sequence.

     Definition Classes
       IndexedSeqLike → TraversableOnce → GenTraversableOnce
135.  def toCollection(repr: Repr): IndexedSeq[A]

     A conversion from collections of type `Repr` to `IndexedSeq` objects.

     A conversion from collections of type `Repr` to `IndexedSeq` objects. By default this is implemented as just a cast, but this can be overridden.

     Attributes
       protected[this]
     Definition Classes
       IndexedSeqLike → SeqLike → IterableLike → TraversableLike
136.  def toIndexedSeq: immutable.IndexedSeq[A]

     Converts this traversable or iterator to an indexed sequence.

     Converts this traversable or iterator to an indexed sequence.

     Note: will not terminate for infinite-sized collections.

     returns

       an indexed sequence containing all elements of this traversable or iterator.

     Definition Classes
       TraversableOnce → GenTraversableOnce
137.  def toIterable: Iterable[A]

     Returns this iterable collection as an iterable collection.

     Returns this iterable collection as an iterable collection.

     A new collection will not be built; lazy collections will stay lazy.

     Note: will not terminate for infinite-sized collections.

     returns

       an `Iterable` containing all elements of this iterable collection.

     Definition Classes
       IterableLike → TraversableOnce → GenTraversableOnce
138.  def toIterator: Iterator[A]

     Returns an Iterator over the elements in this iterable collection.

     Returns an Iterator over the elements in this iterable collection. Produces the same result as `iterator`.

     Note: will not terminate for infinite-sized collections.

     returns

       an Iterator containing all elements of this iterable collection.

     Definition Classes
       IterableLike → TraversableLike → GenTraversableOnce
     Annotations
       @deprecatedOverriding( message = ... , since = "2.11.0" )
139.  def toList: List[A]

     Converts this sequence to a list.

     Converts this sequence to a list.

     returns

       a list containing all elements of this sequence.

     Definition Classes
       IndexedSeqOptimized → TraversableOnce → GenTraversableOnce
140.  def toMap[T, U]: Map[T, U]

     [use case] Converts this sequence to a map.

     [use case]

     Converts this sequence to a map. This method is unavailable unless the elements are members of Tuple2, each ((T, U)) becoming a key-value pair in the map. Duplicate keys will be overwritten by later keys: if this is an unordered collection, which key is in the resulting map is undefined.

     returns

       a map of type `immutable.Map[T, U]` containing all key/value pairs of type `(T, U)` of this sequence.

     Definition Classes
       TraversableOnce → GenTraversableOnce
      Full Signature

     #### def toMap[T, U](implicit ev: <:<[A, (T, U)]): immutable.Map[T, U]

141.  def toParArray: ParArray[T]
     Implicit
       This member is added by an implicit conversion from IndexedSeqOptimized[A, Repr] to CollectionsHaveToParArray[IndexedSeqOptimized[A, Repr], T] performed by method CollectionsHaveToParArray in scala.collection.parallel. This conversion will take place only if an implicit value of type (IndexedSeqOptimized[A, Repr]) ⇒ GenTraversableOnce[T] is in scope.
     Definition Classes
       CollectionsHaveToParArray
142.  def toSeq: Seq[A]

     Converts this sequence to a sequence.

     Converts this sequence to a sequence.

     Note: will not terminate for infinite-sized collections.

     A new collection will not be built; in particular, lazy sequences will stay lazy.

     returns

       a sequence containing all elements of this sequence.

     Definition Classes
       SeqLike → GenSeqLike → TraversableOnce → GenTraversableOnce
143.  def toSet[B >: A]: immutable.Set[B]

     Converts this traversable or iterator to a set.

     Converts this traversable or iterator to a set.

     Note: will not terminate for infinite-sized collections.

     returns

       a set containing all elements of this traversable or iterator.

     Definition Classes
       TraversableOnce → GenTraversableOnce
144.  def toStream: immutable.Stream[A]

     Converts this iterable collection to a stream.

     Converts this iterable collection to a stream.

     returns

       a stream containing all elements of this iterable collection.

     Definition Classes
       IterableLike → TraversableLike → GenTraversableOnce
145.  def toString(): String

     Converts this sequence to a string.

     Converts this sequence to a string.

     returns

       a string representation of this collection. By default this string consists of the `stringPrefix` of this sequence, followed by all elements separated by commas and enclosed in parentheses.

     Definition Classes
       SeqLike → TraversableLike → Any
146.  def toTraversable: Traversable[A]

     Converts this traversable collection to an unspecified Traversable.

     Converts this traversable collection to an unspecified Traversable. Will return the same collection if this instance is already Traversable.

     Note: will not terminate for infinite-sized collections.

     returns

       a Traversable containing all elements of this traversable collection.

     Definition Classes
       TraversableLike → TraversableOnce → GenTraversableOnce
     Annotations
       @deprecatedOverriding( message = ... , since = "2.11.0" )
147.  def toVector: Vector[A]

     Converts this traversable or iterator to a Vector.

     Converts this traversable or iterator to a Vector.

     Note: will not terminate for infinite-sized collections.

     returns

       a vector containing all elements of this traversable or iterator.

     Definition Classes
       TraversableOnce → GenTraversableOnce
148.  def union(that: Seq[A]): IndexedSeq[A]

     [use case] Produces a new sequence which contains all elements of this sequence and also all elements of a given sequence.

     [use case]

     Produces a new sequence which contains all elements of this sequence and also all elements of a given sequence. `xs union ys` is equivalent to `xs ++ ys`.

     Another way to express this is that `xs union ys` computes the order-preserving multi-set union of `xs` and `ys`. `union` is hence a counter-part of `diff` and `intersect` which also work on multi-sets.

     that

       the sequence to add.

     returns

       a new sequence which contains all elements of this sequence followed by all elements of `that`.

     Definition Classes
       SeqLike → GenSeqLike
      Full Signature

     #### def union[B >: A, That](that: GenSeq[B])(implicit bf: CanBuildFrom[Repr, B, That]): That

149.  def updated(index: Int, elem: A): IndexedSeq[A]

     [use case] A copy of this sequence with one single replaced element.

     [use case]

     A copy of this sequence with one single replaced element.

     index

       the position of the replacement

     elem

       the replacing element

     returns

       a copy of this sequence with the element at position `index` replaced by `elem`.

     Definition Classes
       SeqLike → GenSeqLike
      Full Signature

     #### def updated[B >: A, That](index: Int, elem: B)(implicit bf: CanBuildFrom[Repr, B, That]): That

150.  def view(from: Int, until: Int): SeqView[A, Repr]

     Creates a non-strict view of a slice of this sequence.

     Creates a non-strict view of a slice of this sequence.

     Note: the difference between `view` and `slice` is that `view` produces a view of the current sequence, whereas `slice` produces a new sequence.

     Note: `view(from, to)` is equivalent to `view.slice(from, to)`

     from

       the index of the first element of the view

     until

       the index of the element following the view

     returns

       a non-strict view of a slice of this sequence, starting at index `from` and extending up to (but not including) index `until`.

     Definition Classes
       SeqLike → IterableLike → TraversableLike
151.  def view: SeqView[A, Repr]

     Creates a non-strict view of this sequence.

     Creates a non-strict view of this sequence.

     returns

       a non-strict view of this sequence.

     Definition Classes
       SeqLike → IterableLike → TraversableLike
152.  def withFilter(p: (A) ⇒ Boolean): FilterMonadic[A, Repr]

     Creates a non-strict filter of this traversable collection.

     Creates a non-strict filter of this traversable collection.

     Note: the difference between `c filter p` and `c withFilter p` is that the former creates a new collection, whereas the latter only restricts the domain of subsequent `map`, `flatMap`, `foreach`, and `withFilter` operations.

     Note: might return different results for different runs, unless the underlying collection type is ordered.

     p

       the predicate used to test elements.

     returns

       an object of class `WithFilter`, which supports `map`, `flatMap`, `foreach`, and `withFilter` operations. All these operations apply to those elements of this traversable collection which satisfy the predicate `p`.

     Definition Classes
       TraversableLike → FilterMonadic
153.  def zip[B](that: GenIterable[B]): IndexedSeq[(A, B)]

     [use case] Returns a sequence formed from this sequence and another iterable collection by combining corresponding elements in pairs.

     [use case]

     Returns a sequence formed from this sequence and another iterable collection by combining corresponding elements in pairs. If one of the two collections is longer than the other, its remaining elements are ignored.

     B

       the type of the second half of the returned pairs

     that

       The iterable providing the second half of each result pair

     returns

       a new sequence containing pairs consisting of corresponding elements of this sequence and `that`. The length of the returned collection is the minimum of the lengths of this sequence and `that`.

     Definition Classes
       IndexedSeqOptimized → IterableLike → GenIterableLike
      Full Signature

     #### def zip[A1 >: A, B, That](that: GenIterable[B])(implicit bf: CanBuildFrom[Repr, (A1, B), That]): That

154.  def zipAll[B](that: Iterable[B], thisElem: A, thatElem: B): IndexedSeq[(A, B)]

     [use case] Returns a sequence formed from this sequence and another iterable collection by combining corresponding elements in pairs.

     [use case]

     Returns a sequence formed from this sequence and another iterable collection by combining corresponding elements in pairs. If one of the two collections is shorter than the other, placeholder elements are used to extend the shorter collection to the length of the longer.

     B

       the type of the second half of the returned pairs

     that

       The iterable providing the second half of each result pair

     thisElem

       the element to be used to fill up the result if this sequence is shorter than `that`.

     thatElem

       the element to be used to fill up the result if `that` is shorter than this sequence.

     returns

       a new sequence containing pairs consisting of corresponding elements of this sequence and `that`. The length of the returned collection is the maximum of the lengths of this sequence and `that`. If this sequence is shorter than `that`, `thisElem` values are used to pad the result. If `that` is shorter than this sequence, `thatElem` values are used to pad the result.

     Definition Classes
       IterableLike → GenIterableLike
      Full Signature

     #### def zipAll[B, A1 >: A, That](that: GenIterable[B], thisElem: A1, thatElem: B)(implicit bf: CanBuildFrom[Repr, (A1, B), That]): That

155.  def zipWithIndex: IndexedSeq[(A, Int)]

     [use case] Zips this sequence with its indices.

     [use case]

     Zips this sequence with its indices.

     returns

       A new sequence containing pairs consisting of all elements of this sequence paired with their index. Indices start at `0`.

     Definition Classes
       IndexedSeqOptimized → IterableLike → GenIterableLike
      Full Signature

     #### def zipWithIndex[A1 >: A, That](implicit bf: CanBuildFrom[Repr, (A1, Int), That]): That

     Example:

     1. `List("a", "b", "c").zipWithIndex = List(("a", 0), ("b", 1), ("c", 2))`

156.  def →[B](y: B): (IndexedSeqOptimized[A, Repr], B)
     Implicit
       This member is added by an implicit conversion from IndexedSeqOptimized[A, Repr] to ArrowAssoc[IndexedSeqOptimized[A, Repr]] performed by method ArrowAssoc in scala.Predef.
     Definition Classes
       ArrowAssoc

### Shadowed Implicit Value Members

1.  def filter(p: (A) ⇒ Boolean): TraversableOnce[A]
   Implicit
     This member is added by an implicit conversion from IndexedSeqOptimized[A, Repr] to MonadOps[A] performed by method MonadOps in scala.collection.TraversableOnce.
   Shadowing
     This implicitly inherited member is shadowed by one or more members in this class.
     To access this member you can use a type ascription:

         (indexedSeqOptimized: MonadOps[A]).filter(p)

   Definition Classes
     MonadOps
2.  def flatMap[B](f: (A) ⇒ GenTraversableOnce[B]): TraversableOnce[B]
   Implicit
     This member is added by an implicit conversion from IndexedSeqOptimized[A, Repr] to MonadOps[A] performed by method MonadOps in scala.collection.TraversableOnce.
   Shadowing
     This implicitly inherited member is shadowed by one or more members in this class.
     To access this member you can use a type ascription:

         (indexedSeqOptimized: MonadOps[A]).flatMap(f)

   Definition Classes
     MonadOps
3.  def map[B](f: (A) ⇒ B): TraversableOnce[B]
   Implicit
     This member is added by an implicit conversion from IndexedSeqOptimized[A, Repr] to MonadOps[A] performed by method MonadOps in scala.collection.TraversableOnce.
   Shadowing
     This implicitly inherited member is shadowed by one or more members in this class.
     To access this member you can use a type ascription:

         (indexedSeqOptimized: MonadOps[A]).map(f)

   Definition Classes
     MonadOps
4.  def withFilter(p: (A) ⇒ Boolean): Iterator[A]
   Implicit
     This member is added by an implicit conversion from IndexedSeqOptimized[A, Repr] to MonadOps[A] performed by method MonadOps in scala.collection.TraversableOnce.
   Shadowing
     This implicitly inherited member is shadowed by one or more members in this class.
     To access this member you can use a type ascription:

         (indexedSeqOptimized: MonadOps[A]).withFilter(p)

   Definition Classes
     MonadOps

### Deprecated Value Members

1.  def /:[B](z: B)(op: (B, A) ⇒ B): B

   Applies a binary operator to a start value and all elements of this traversable or iterator, going left to right.

   Applies a binary operator to a start value and all elements of this traversable or iterator, going left to right.

   Note: `/:` is alternate syntax for `foldLeft`; `z /: xs` is the same as `xs foldLeft z`.

   Examples:

   Note that the folding function used to compute b is equivalent to that used to compute c.

       scala> val a = List(1,2,3,4)
       a: List[Int] = List(1, 2, 3, 4)

       scala> val b = (5 /: a)(_+_)
       b: Int = 15

       scala> val c = (5 /: a)((x,y) => x + y)
       c: Int = 15

   Note: will not terminate for infinite-sized collections.

   Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

   B

     the result type of the binary operator.

   z

     the start value.

   op

     the binary operator.

   returns

     the result of inserting `op` between consecutive elements of this traversable or iterator, going left to right with the start value `z` on the left:

         op(...op(op(z, x_1), x_2), ..., x_n)

     where `x1, ..., xn` are the elements of this traversable or iterator.

   Definition Classes
     TraversableOnce → GenTraversableOnce
   Annotations
     @deprecated
   Deprecated

     (Since version 2.12.10) Use foldLeft instead of /:

2.  def :\[B](z: B)(op: (A, B) ⇒ B): B

   Applies a binary operator to all elements of this traversable or iterator and a start value, going right to left.

   Applies a binary operator to all elements of this traversable or iterator and a start value, going right to left.

   Note: `:\` is alternate syntax for `foldRight`; `xs :\ z` is the same as `xs foldRight z`.

   Note: will not terminate for infinite-sized collections.

   Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.

   Examples:

   Note that the folding function used to compute b is equivalent to that used to compute c.

       scala> val a = List(1,2,3,4)
       a: List[Int] = List(1, 2, 3, 4)

       scala> val b = (a :\ 5)(_+_)
       b: Int = 15

       scala> val c = (a :\ 5)((x,y) => x + y)
       c: Int = 15

   B

     the result type of the binary operator.

   z

     the start value

   op

     the binary operator

   returns

     the result of inserting `op` between consecutive elements of this traversable or iterator, going right to left with the start value `z` on the right:

         op(x_1, op(x_2, ... op(x_n, z)...))

     where `x1, ..., xn` are the elements of this traversable or iterator.

   Definition Classes
     TraversableOnce → GenTraversableOnce
   Annotations
     @deprecated
   Deprecated

     (Since version 2.12.10) Use foldRight instead of :\

3.  def formatted(fmtstr: String): String

   Returns string formatted according to given `format` string.

   Returns string formatted according to given `format` string. Format strings are as for `String.format` (@see java.lang.String.format).

   Implicit
     This member is added by an implicit conversion from IndexedSeqOptimized[A, Repr] to StringFormat[IndexedSeqOptimized[A, Repr]] performed by method StringFormat in scala.Predef.
   Definition Classes
     StringFormat
   Annotations
     @deprecated @inline()
   Deprecated

     (Since version 2.12.16) Use `formatString.format(value)` instead of `value.formatted(formatString)`, or use the `f""` string interpolator. In Java 15 and later, `formatted` resolves to the new method in String which has reversed parameters.

### Inherited from IndexedSeqLike[A, Repr]

### Inherited from SeqLike[A, Repr]

### Inherited from GenSeqLike[A, Repr]

### Inherited from IterableLike[A, Repr]

### Inherited from GenIterableLike[A, Repr]

### Inherited from TraversableLike[A, Repr]

### Inherited from GenTraversableLike[A, Repr]

### Inherited from Parallelizable[A, ParSeq[A]]

### Inherited from TraversableOnce[A]

### Inherited from GenTraversableOnce[A]

### Inherited from FilterMonadic[A, Repr]

### Inherited from HasNewBuilder[A, Repr]

### Inherited from Equals

### Inherited from Any

### Inherited by implicit conversion CollectionsHaveToParArray from IndexedSeqOptimized[A, Repr] to CollectionsHaveToParArray[IndexedSeqOptimized[A, Repr], T]

### Inherited by implicit conversion MonadOps from IndexedSeqOptimized[A, Repr] to MonadOps[A]

### Inherited by implicit conversion any2stringadd from IndexedSeqOptimized[A, Repr] to any2stringadd[IndexedSeqOptimized[A, Repr]]

### Inherited by implicit conversion StringFormat from IndexedSeqOptimized[A, Repr] to StringFormat[IndexedSeqOptimized[A, Repr]]

### Inherited by implicit conversion Ensuring from IndexedSeqOptimized[A, Repr] to Ensuring[IndexedSeqOptimized[A, Repr]]

### Inherited by implicit conversion ArrowAssoc from IndexedSeqOptimized[A, Repr] to ArrowAssoc[IndexedSeqOptimized[A, Repr]]

### Inherited by implicit conversion alternateImplicit from IndexedSeqOptimized[A, Repr] to ForceImplicitAmbiguity

### Ungrouped