SeqOps

scala.collection.SeqOps

See theSeqOps companion object

trait SeqOps[+A, +CC[_], +C] extends IterableOps[A, CC, C]

Base trait for Seq operations

Type parameters

A: the element type of the collection
C: type of the collection (e.g. List[Int], String, BitSet). Operations returning a collection with the same type of element (e.g. drop, filter) return a C.
CC: type constructor of the collection (e.g. List, Set). Operations returning a collection with a different type of element B (e.g. map) return a CC[B].

Attributes

Companion: object
Source: Seq.scala
Graph
Supertypes: trait IterableOps[A, CC, C]

trait IterableOnceOps[A, CC, C]

trait IterableOnce[A]

class Any
Known subtypes: trait SeqOps[A, CC, C]

trait IndexedSeqOps[A, CC, C]

class ArraySeq[A]

class ofBoolean

class ofByte

class ofChar

class ofDouble

class ofFloat

class ofInt

class ofLong

class ofRef[T]

class ofShort

class ofUnit

trait IndexedSeq[A]

class NumericRange[T]

class Exclusive[T]

class Inclusive[T]

class Range

class Exclusive

class Inclusive

class Vector[A]

class WrappedString

trait LinearSeqOps[A, CC, C]

class LazyList[A]

trait LinearSeq[A]

class List[A]

class ::[A]

object Nil

class Queue[A]

class Stream[A]

class Cons[A]

object Empty

trait Seq[A]

class AbstractSeq[A]

trait StrictOptimizedSeqOps[A, CC, C]

trait SeqOps[A, CC, C]

trait Buffer[A]

class AbstractBuffer[A]

class ArrayBuffer[A]

class ArrayDeque[A]

class Queue[A]

class Stack[A]

class ListBuffer[A]

class UnrolledBuffer[T]

trait IndexedBuffer[A]

trait IndexedSeqOps[A, CC, C]

class ArraySeq[T]

class ofBoolean

class ofByte

class ofChar

class ofDouble

class ofFloat

class ofInt

class ofLong

class ofRef[T]

class ofShort

class ofUnit

trait IndexedSeq[T]

class StringBuilder

trait Seq[A]

class AbstractSeq[A]

class Accumulator[A, CC, C]

class AnyAccumulator[A]

class DoubleAccumulator

class IntAccumulator

class LongAccumulator

trait IndexedSeqOps[A, CC, C]

trait IndexedSeq[A]

trait IndexedSeqView[A]

class AbstractIndexedSeqView[A]

class ArrayBufferView[A]

class Slice[A]

class StringView

class Appended[A]

class Concat[A]

class Drop[A]

class DropRight[A]

class Id[A]

class Map[A, B]

class Prepended[A]

class Reverse[A]

class Take[A]

class TakeRight[A]

trait LinearSeqOps[A, CC, C]

trait LinearSeq[A]

trait StrictOptimizedLinearSeqOps[A, CC, C]

trait Seq[A]

class AbstractSeq[A]

trait SeqView[A]

class AbstractSeqView[A]

class Id[A]

class Reverse[A]

class Appended[A]

class Concat[A]

class Drop[A]

class DropRight[A]

class Map[A, B]

class Prepended[A]

class Sorted[A, B]

class Take[A]

class TakeRight[A]

trait StrictOptimizedSeqOps[A, CC, C]

trait ArrayDequeOps[A, CC, C]
Show all
Self type: SeqOps[A, CC, C]

Members list

Value members

Abstract methods

Get the element at the specified index.

Get the element at the specified index. This operation is provided for convenience in Seq. It should not be assumed to be efficient unless you have an IndexedSeq.

Attributes

Source: Seq.scala

The length (number of elements) of the sequence.

The length (number of elements) of the sequence. size is an alias for length in Seq collections.

Attributes

Source: Seq.scala

Concrete methods

Alias for prependedAll

Attributes

Definition Classes: IterableOps
Source: Seq.scala

Alias for prepended.

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

Attributes

Source: Seq.scala

Alias for appended

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

Attributes

Source: Seq.scala

Alias for appendedAll

Attributes

Source: Seq.scala

A copy of this sequence with an element appended.

Note: will not terminate for infinite-sized collections.

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)

Type parameters

B: the element type of the returned sequence.

Value parameters

elem: the appended element

Attributes

Returns: a new sequence consisting of all elements of this sequence followed by value.
Source: Seq.scala

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

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

Type parameters

B: the element type of the returned collection.

Value parameters

suffix: the iterable to append.

Attributes

Returns: a new collection of type CC[B] which contains all elements of this sequence followed by all elements of suffix.
Source: Seq.scala

Iterates over combinations of elements.

A combination of length n is a sequence of n elements selected in order of their first index in this sequence.

For example, "xyx" has two combinations of length 2. The x is selected first: "xx", "xy". The sequence "yx" is not returned as a combination because it is subsumed by "xy".

If there is more than one way to generate the same combination, only one will be returned.

For example, the result "xy" arbitrarily selected one of the x elements.

As a further illustration, "xyxx" has three different ways to generate "xy" because there are three elements x to choose from. Moreover, there are three unordered pairs "xx" but only one is returned.

It is not specified which of these equal combinations is returned. It is an implementation detail that should not be relied on. For example, the combination "xx" does not necessarily contain the first x in this sequence. This behavior is observable if the elements compare equal but are not identical.

As a consequence, "xyx".combinations(3).next() is "xxy": the combination does not reflect the order of the original sequence, but the order in which elements were selected, by "first index"; the order of each x element is also arbitrary.

Note: Even when applied to a view or a lazy collection it will always force the elements.

Attributes

Returns

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

Example

Seq('a', 'b', 'b', 'b', 'c').combinations(2).foreach(println)
// List(a, b)
// List(a, c)
// List(b, b)
// List(b, c)
Seq('b', 'a', 'b').combinations(2).foreach(println)
// List(b, b)
// List(b, a)

Source

Seq.scala

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

Type parameters

B: the element type of the returned collection.

Value parameters

suffix: the iterable to append.

Attributes

Returns: a new sequence which contains all elements of this sequence followed by all elements of suffix.
Definition Classes: IterableOps
Source: Seq.scala

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

Note: may not terminate for infinite-sized collections.

Value parameters

elem: the element to test.

Attributes

Returns: true if this sequence has an element that is equal (as determined by ==) to elem, false otherwise.
Source: Seq.scala

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

Note: may not terminate for infinite-sized collections.

Value parameters

that: the sequence to test

Attributes

Returns: true if this sequence contains a slice with the same elements as that, otherwise false.
Source: Seq.scala

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

Type parameters

B: the type of the elements of that

Value parameters

p: the test predicate, which relates elements from both sequences
that: the other sequence

Attributes

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.
Source: Seq.scala

Computes the multiset difference between this sequence and another sequence.

Value parameters

that: the sequence of elements to remove

Attributes

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.
Source: Seq.scala

Selects all the elements of this sequence ignoring the duplicates.

Attributes

Returns: a new sequence consisting of all the elements of this sequence without duplicates.
Source: Seq.scala

Selects all the elements of this sequence ignoring the duplicates as determined by == after applying the transforming function f.

Type parameters

B: the type of the elements after being transformed by f

Value parameters

f: The transforming function whose result is used to determine the uniqueness of each element

Attributes

Returns: a new sequence consisting of all the elements of this sequence without duplicates.
Source: Seq.scala

Tests whether this sequence ends with the given sequence.

Note: will not terminate for infinite-sized collections.

Value parameters

that: the sequence to test

Attributes

Returns: true if this sequence has that as a suffix, false otherwise.
Source: Seq.scala

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

Note: will not terminate for infinite-sized collections.

Value parameters

p: the predicate used to test elements.

Attributes

Returns: an option value containing the last element in the sequence that satisfies p, or None if none exists.
Source: Seq.scala

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

Type parameters

B: the type of the element elem.

Value parameters

elem: the element value to search for.
from: the start index

Attributes

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

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

Type parameters

B: the type of the element elem.

Value parameters

elem: the element value to search for.

Attributes

Returns: the index >= 0 of the first element of this sequence that is equal (as determined by ==) to elem, or -1, if none exists.
Source: Seq.scala

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.

Value parameters

from: the start index
that: the sequence to test

Attributes

Returns: the first index >= from such that the elements of this sequence starting at this index match the elements of sequence that, or -1 if no such subsequence exists.
Source: Seq.scala

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

Note: may not terminate for infinite-sized collections.

Value parameters

that: the sequence to test

Attributes

Returns: the first index >= 0 such that the elements of this sequence starting at this index match the elements of sequence that, or -1 if no such subsequence exists.
Source: Seq.scala

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

Note: may not terminate for infinite-sized collections.

Value parameters

from: the start index
p: the predicate used to test elements.

Attributes

Returns: the index >= from of the first element of this sequence that satisfies the predicate p, or -1, if none exists.
Source: Seq.scala

Finds index of the first element satisfying some predicate.

Note: may not terminate for infinite-sized collections.

Value parameters

p: the predicate used to test elements.

Attributes

Returns: the index >= 0 of the first element of this sequence that satisfies the predicate p, or -1, if none exists.
Source: Seq.scala

Produces the range of all indices of this sequence.

Note: Even when applied to a view or a lazy collection it will always force the elements.

Attributes

Returns: a Range value from 0 to one less than the length of this sequence.
Source: Seq.scala

Computes the multiset intersection between this sequence and another sequence.

Value parameters

that: the sequence of elements to intersect with.

Attributes

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.
Source: Seq.scala

Tests whether this sequence contains given index.

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

Value parameters

idx: the index to test

Attributes

Returns: true if this sequence contains an element at position idx, false otherwise.
Source: Seq.scala

Tests whether the sequence is empty.

Note: Implementations in subclasses that are not repeatedly iterable must take care not to consume any elements when isEmpty is called.

Attributes

Returns: true if the sequence contains no elements, false otherwise.
Definition Classes: IterableOnceOps
Source: Seq.scala

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

Note: will not terminate for infinite-sized collections.

Type parameters

B: the type of the element elem.

Value parameters

elem: the element value to search for.
end: the end index.

Attributes

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

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

Note: will not terminate for infinite-sized collections.

Value parameters

end: the end index
that: the sequence to test

Attributes

Returns: the last index <= end such that the elements of this sequence starting at this index match the elements of sequence that, or -1 if no such subsequence exists.
Source: Seq.scala

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

Note: will not terminate for infinite-sized collections.

Value parameters

that: the sequence to test

Attributes

Returns: the last index such that the elements of this sequence starting at this index match the elements of sequence that, or -1 if no such subsequence exists.
Source: Seq.scala

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

Note: will not terminate for infinite-sized collections.

Value parameters

p: the predicate used to test elements.

Attributes

Returns: the index <= end of the last element of this sequence that satisfies the predicate p, or -1, if none exists.
Source: Seq.scala

Finds index of last element satisfying some predicate.

Note: will not terminate for infinite-sized collections.

Value parameters

p: the predicate used to test elements.

Attributes

Returns: the index of the last element of this sequence that satisfies the predicate p, or -1, if none exists.
Source: Seq.scala

Compares the length of this sequence to a test value.

Value parameters

len: the test value that gets compared with the length.

Attributes

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 overridden if computing length is cheap and knownSize returns -1.

See also

lengthIs

Source

Seq.scala

Compares the length of this sequence to the size of another Iterable.

Value parameters

that: the Iterable whose size is compared with this sequence's length.

Attributes

Returns

A value x where

x <  0       if this.length <  that.size
x == 0       if this.length == that.size
x >  0       if this.length >  that.size

The method as implemented here does not call length or size directly; its running time is O(this.length min that.size) instead of O(this.length + that.size). The method should be overridden if computing size is cheap and knownSize returns -1.

Source

Seq.scala

Returns a value class containing operations for comparing the length of this sequence to a test value.

These operations are implemented in terms of lengthCompare(Int), and allow the following more readable usages:

this.lengthIs < len     // this.lengthCompare(len) < 0
this.lengthIs <= len    // this.lengthCompare(len) <= 0
this.lengthIs == len    // this.lengthCompare(len) == 0
this.lengthIs != len    // this.lengthCompare(len) != 0
this.lengthIs >= len    // this.lengthCompare(len) >= 0
this.lengthIs > len     // this.lengthCompare(len) > 0

Attributes

Source: Seq.scala

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

Type parameters

B: the element type of the returned sequence.

Value parameters

elem: the padding value
len: the target length

Attributes

Returns: a new sequence consisting of all elements of this sequence followed by the minimal number of occurrences of elem so that the resulting collection has a length of at least len.
Source: Seq.scala

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

Patching at negative indices is the same as patching starting at 0. Patching at indices at or larger than the length of the original sequence appends the patch to the end. If more values are replaced than actually exist, the excess is ignored.

Type parameters

B: the element type of the returned sequence.

Value parameters

from: the index of the first replaced element
other: the replacement sequence
replaced: the number of elements to drop in the original sequence

Attributes

Returns: a new sequence consisting of all elements of this sequence except that replaced elements starting from from are replaced by all the elements of other.
Source: Seq.scala

Iterates over distinct permutations of elements.

Note: Even when applied to a view or a lazy collection it will always force the elements.

Attributes

Returns

An Iterator which traverses the distinct permutations of this sequence.

Example

Seq('a', 'b', 'b').permutations.foreach(println)
// List(a, b, b)
// List(b, a, b)
// List(b, b, a)

Source

Seq.scala

A copy of the sequence with an element prepended.

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)

Type parameters

B: the element type of the returned sequence.

Value parameters

elem: the prepended element

Attributes

Returns: a new sequence consisting of value followed by all elements of this sequence.
Source: Seq.scala

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.

Type parameters

B: the element type of the returned collection.

Value parameters

prefix: the iterable to prepend.

Attributes

Returns: a new sequence which contains all elements of prefix followed by all the elements of this sequence.
Source: Seq.scala

Returns new sequence with elements in reversed order.

Note: will not terminate for infinite-sized collections.

Note: Even when applied to a view or a lazy collection it will always force the elements.

Attributes

Returns: A new sequence with all elements of this sequence in reversed order.
Source: Seq.scala

An iterator yielding elements in reversed order.

Note: will not terminate for infinite-sized collections.

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

Attributes

Returns: an iterator yielding the elements of this sequence in reversed order
Source: Seq.scala

Are the elements of this collection the same (and in the same order) as those of that?

Attributes

Source: Seq.scala

Search this sorted sequence for a specific element.

Search this sorted sequence for a specific element. If the sequence is an IndexedSeq, a binary search is used. Otherwise, a linear search is used.

The sequence should be sorted with the same Ordering before calling; otherwise, the results are undefined.

Value parameters

elem: the element to find.
ord: the ordering to be used to compare elements.

Attributes

Returns: a Found value containing the index corresponding to the element in the sequence, or the InsertionPoint where the element would be inserted if the element is not in the sequence.
See also: scala.collection.IndexedSeq

scala.math.Ordering

scala.collection.SeqOps, method sorted
Source: Seq.scala

Search within an interval in this sorted sequence for a specific element.

Search within an interval in this sorted sequence for a specific element. If this sequence is an IndexedSeq, a binary search is used. Otherwise, a linear search is used.

The sequence should be sorted with the same Ordering before calling; otherwise, the results are undefined.

Value parameters

elem: the element to find.
from: the index where the search starts.
ord: the ordering to be used to compare elements.
to: the index following where the search ends.

Attributes

Returns: a Found value containing the index corresponding to the element in the sequence, or the InsertionPoint where the element would be inserted if the element is not in the sequence.
See also: scala.collection.IndexedSeq

scala.math.Ordering

scala.collection.SeqOps, method sorted
Note: if to <= from, the search space is empty, and an InsertionPoint at from is returned
Source: Seq.scala

Computes the length of the longest segment that starts from the first element and whose elements all satisfy some predicate.

Note: may not terminate for infinite-sized collections.

Value parameters

p: the predicate used to test elements.

Attributes

Returns: the length of the longest segment of this sequence that starts from the first element such that every element of the segment satisfies the predicate p.
Source: Seq.scala

Computes the length of the longest segment that starts from some index and whose elements all satisfy some predicate.

Note: may not terminate for infinite-sized collections.

Value parameters

from: the index where the search starts.
p: the predicate used to test elements.

Attributes

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.
Source: Seq.scala

The size of this sequence.

Note: will not terminate for infinite-sized collections.

Attributes

Returns: the number of elements in this sequence.
Definition Classes: IterableOnceOps
Source: Seq.scala

Compares the size of this sequence to a test value.

Value parameters

otherSize: the test value that gets compared with the size.

Attributes

Returns

A value x where

x <  0       if this.size <  otherSize
x == 0       if this.size == otherSize
x >  0       if this.size >  otherSize

The method as implemented here does not call size directly; its running time is O(size min otherSize) instead of O(size). The method should be overridden if computing size is cheap and knownSize returns -1.

See also

sizeIs

Definition Classes

IterableOps

Source

Seq.scala

Compares the size of this sequence to the size of another Iterable.

Value parameters

that: the Iterable whose size is compared with this sequence's size.

Attributes

Returns

A value x where

x <  0       if this.size <  that.size
x == 0       if this.size == that.size
x >  0       if this.size >  that.size

The method as implemented here does not call size directly; its running time is O(this.size min that.size) instead of O(this.size + that.size). The method should be overridden if computing size is cheap and knownSize returns -1.

Definition Classes

IterableOps

Source

Seq.scala

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

Note: will not terminate for infinite-sized collections.

Note: Even when applied to a view or a lazy collection it will always force the elements.

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

Type parameters

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

Value parameters

f: the transformation function mapping elements to some other domain B.
ord: the ordering assumed on domain B.

Attributes

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)).

See also

scala.math.Ordering

Example

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)

Source

Seq.scala

Sorts this sequence according to a comparison function.

Note: will not terminate for infinite-sized collections.

Note: Even when applied to a view or a lazy collection it will always force the elements.

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.

Value parameters

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

Attributes

Returns

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

Example

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

Source

Seq.scala

Sorts this sequence according to an Ordering.

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

Value parameters

ord: the ordering to be used to compare elements.

Attributes

Returns: a sequence consisting of the elements of this sequence sorted according to the ordering ord.
See also: scala.math.Ordering Note: Even when applied to a view or a lazy collection it will always force the elements.
Source: Seq.scala

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.

Value parameters

offset: the index where the sequence is searched.
that: the sequence to test

Attributes

Returns: true if the sequence that is contained in this sequence at index offset, otherwise false.
Source: Seq.scala

A copy of this sequence with one single replaced element.

Type parameters

B: the element type of the returned sequence.

Value parameters

elem: the replacing element
index: the position of the replacement

Attributes

Returns: a new sequence which is a copy of this sequence with the element at position index replaced by elem.
Throws: IndexOutOfBoundsException if index does not satisfy 0 <= index < length. In case of a lazy collection this exception may be thrown at a later time or not at all (if the end of the collection is never evaluated).
Source: Seq.scala

A view over the elements of this collection.

Attributes

Definition Classes: IterableOps
Source: Seq.scala

Deprecated methods

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

Note: may not terminate for infinite-sized collections.

Value parameters

p: the predicate used to test elements.

Attributes

Returns: the length of the longest prefix of this sequence such that every element of the segment satisfies the predicate p.
Deprecated: true
Source: Seq.scala

Attributes

Deprecated: true
Source: Seq.scala

Produces a new sequence which contains all elements of this sequence and also all elements of a given sequence.

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.

Type parameters

B: the element type of the returned sequence.

Value parameters

that: the sequence to add.

Attributes

Returns: a new collection which contains all elements of this sequence followed by all elements of that.
Deprecated: true
Source: Seq.scala

Inherited methods

Alias for concat

Attributes

Inherited from:: IterableOps
Source: Iterable.scala

Appends all elements of this collection to a string builder.

Appends all elements of this collection to a string builder. The written text consists of the string representations (w.r.t. the method toString) of all elements of this collection 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

Value parameters

b: the string builder to which elements are appended.

Attributes

Returns: the string builder b to which elements were appended.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Appends all elements of this collection to a string builder using a separator string.

Appends all elements of this collection 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 collection, 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

Value parameters

b: the string builder to which elements are appended.
sep: the separator string.

Attributes

Returns: the string builder b to which elements were appended.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

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

Appends all elements of this collection 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 collection 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)

Value parameters

b: the string builder to which elements are appended.
end: the ending string.
sep: the separator string.
start: the starting string.

Attributes

Returns: the string builder b to which elements were appended.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

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

Type parameters

B: the element type of the returned iterable collection.

Value parameters

pf: the partial function which filters and maps the iterable collection.

Attributes

Returns: a new iterable collection 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.
Inherited from:: IterableOps
Source: Iterable.scala

Finds the first element of the collection 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.

Value parameters

pf: the partial function

Attributes

Returns: an option value containing pf applied to the first value for which it is defined, or None if none exists.
Example: Seq("a", 1, 5L).collectFirst({ case x: Int => x*10 }) = Some(10)
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Copy elements to an array, returning the number of elements written.

Fills the given array xs starting at index start with at most len elements of this collection.

Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached, or len elements have been copied.

Type parameters

B: the type of the elements of the array.

Value parameters

len: the maximal number of elements to copy.
start: the starting index of xs.
xs: the array to fill.

Attributes

Returns: the number of elements written to the array
Note: Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Copy elements to an array, returning the number of elements written.

Fills the given array xs starting at index start with values of this collection.

Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached.

Type parameters

B: the type of the elements of the array.

Value parameters

start: the starting index of xs.
xs: the array to fill.

Attributes

Returns: the number of elements written to the array
Note: Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Copy elements to an array, returning the number of elements written.

Fills the given array xs starting at index start with values of this collection.

Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached.

Type parameters

B: the type of the elements of the array.

Value parameters

xs: the array to fill.

Attributes

Returns: the number of elements written to the array
Note: Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Tests whether every element of this collection's iterator relates to the corresponding element of another collection by satisfying a test predicate.

Note: will not terminate for infinite-sized collections.

Type parameters

B: the type of the elements of that

Value parameters

p: the test predicate, which relates elements from both collections
that: the other collection

Attributes

Returns: true if both collections have the same length and p(x, y) is true for all corresponding elements x of this iterator and y of that, otherwise false
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Counts the number of elements in the collection which satisfy a predicate.

Note: will not terminate for infinite-sized collections.

Value parameters

p: the predicate used to test elements.

Attributes

Returns: the number of elements satisfying the predicate p.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Selects all elements except first n ones.

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

Value parameters

n: the number of elements to drop from this iterable collection.

Attributes

Returns: a iterable collection consisting of all elements of this iterable collection except the first n ones, or else the empty iterable collection, if this iterable collection has less than n elements. If n is negative, don't drop any elements.
Inherited from:: IterableOps
Source: Iterable.scala

Selects all elements except last n ones.

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

Value parameters

n: the number of elements to drop from this iterable collection.

Attributes

Returns: a iterable collection consisting of all elements of this iterable collection except the last n ones, or else the empty iterable collection, if this iterable collection has less than n elements. If n is negative, don't drop any elements.
Inherited from:: IterableOps
Source: Iterable.scala

Drops longest prefix of elements that satisfy a predicate.

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

Value parameters

p: The predicate used to test elements.

Attributes

Returns: the longest suffix of this iterable collection whose first element does not satisfy the predicate p.
Inherited from:: IterableOps
Source: Iterable.scala

The empty iterable of the same type as this iterable

Attributes

Returns: an empty iterable of type C.
Inherited from:: IterableOps
Source: Iterable.scala

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

Note: may not terminate for infinite-sized collections.

Value parameters

p: the predicate used to test elements.

Attributes

Returns: true if the given predicate p is satisfied by at least one element of this collection, otherwise false
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

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

Value parameters

p: the predicate used to test elements.

Attributes

Returns: a new iterable collection consisting of all elements of this iterable collection that satisfy the given predicate p. The order of the elements is preserved.
Inherited from:: IterableOps
Source: Iterable.scala

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

Value parameters

pred: the predicate used to test elements.

Attributes

Returns: a new iterable collection consisting of all elements of this iterable collection that do not satisfy the given predicate pred. Their order may not be preserved.
Inherited from:: IterableOps
Source: Iterable.scala

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

Note: may not terminate for infinite-sized collections.

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

Value parameters

p: the predicate used to test elements.

Attributes

Returns: an option value containing the first element in the collection that satisfies p, or None if none exists.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Builds a new iterable collection by applying a function to all elements of this iterable collection 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 iterable collection. 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: String) => 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)

Type parameters

B: the element type of the returned collection.

Value parameters

f: the function to apply to each element.

Attributes

Returns: a new iterable collection resulting from applying the given collection-valued function f to each element of this iterable collection and concatenating the results.
Inherited from:: IterableOps
Source: Iterable.scala

Converts this iterable collection of iterable collections into a iterable collection formed by the elements of these iterable collections.

The resulting collection's type will be guided by the type of iterable collection. For example:

val xs = List(
           Set(1, 2, 3),
           Set(1, 2, 3)
         ).flatten
// xs == List(1, 2, 3, 1, 2, 3)

val ys = Set(
           List(1, 2, 3),
           List(3, 2, 1)
         ).flatten
// ys == Set(1, 2, 3)

Type parameters

B: the type of the elements of each iterable collection.

Value parameters

asIterable: an implicit conversion which asserts that the element type of this iterable collection is an Iterable.

Attributes

Returns: a new iterable collection resulting from concatenating all element iterable collections.
Inherited from:: IterableOps
Source: Iterable.scala

Folds the elements of this collection using the specified associative binary operator.

Folds the elements of this collection using the specified associative binary operator. The default implementation in IterableOnce is equivalent to foldLeft but may be overridden for more efficient traversal orders.

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

Note: will not terminate for infinite-sized collections.

Type parameters

A1: a type parameter for the binary operator, a supertype of A.

Value parameters

op: a binary operator that must be associative.
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).

Attributes

Returns: the result of applying the fold operator op between all the elements and z, or z if this collection is empty.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Applies a binary operator to a start value and all elements of this collection, 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.

Type parameters

B: the result type of the binary operator.

Value parameters

op: the binary operator.
z: the start value.

Attributes

Returns: the result of inserting op between consecutive elements of this collection, going left to right with the start value z on the left: op(...op(z, x1), x2, ..., xn) where x1, ..., xn are the elements of this collection. Returns z if this collection is empty.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Applies a binary operator to all elements of this collection and a start value, 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.

Type parameters

B: the result type of the binary operator.

Value parameters

op: the binary operator.
z: the start value.

Attributes

Returns: the result of inserting op between consecutive elements of this collection, going right to left with the start value z on the right: op(x1, op(x2, ... op(xn, z)...)) where x1, ..., xn are the elements of this collection. Returns z if this collection is empty.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

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

Note: may not terminate for infinite-sized collections.

Value parameters

p: the predicate used to test elements.

Attributes

Returns: true if this collection is empty or the given predicate p holds for all elements of this collection, otherwise false.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Apply f to each element for its side effects Note: [U] parameter needed to help scalac's type inference.

Attributes

Inherited from:: IterableOnceOps
Source: IterableOnce.scala

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

Note: Even when applied to a view or a lazy collection it will always force the elements.

Type parameters

K: the type of keys returned by the discriminator function.

Value parameters

f: the discriminator function.

Attributes

Returns

A map from keys to iterable 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 iterable collection of those elements x for which f(x) equals k.

Inherited from:

IterableOps

Source

Iterable.scala

Partitions this iterable collection into a map of iterable collections according to a discriminator function key.

Partitions this iterable collection into a map of iterable collections according to a discriminator function key. Each element in a group is transformed into a value of type B using the value function.

It is equivalent to groupBy(key).mapValues(_.map(f)), but more efficient.

case class User(name: String, age: Int)

def namesByAge(users: Seq[User]): Map[Int, Seq[String]] =
  users.groupMap(_.age)(_.name)

Note: Even when applied to a view or a lazy collection it will always force the elements.

Type parameters

B: the type of values returned by the transformation function
K: the type of keys returned by the discriminator function

Value parameters

f: the element transformation function
key: the discriminator function

Attributes

Inherited from:: IterableOps
Source: Iterable.scala

Partitions this iterable collection into a map according to a discriminator function key.

Partitions this iterable collection into a map according to a discriminator function key. All the values that have the same discriminator are then transformed by the f function and then reduced into a single value with the reduce function.

It is equivalent to groupBy(key).mapValues(_.map(f).reduce(reduce)), but more efficient.

def occurrences[A](as: Seq[A]): Map[A, Int] =
  as.groupMapReduce(identity)(_ => 1)(_ + _)

Note: Even when applied to a view or a lazy collection it will always force the elements.

Attributes

Inherited from:: IterableOps
Source: Iterable.scala

Partitions elements in fixed size iterable collections.

Value parameters

size: the number of elements per group

Attributes

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.
See also: scala.collection.Iterator, method grouped
Inherited from:: IterableOps
Source: Iterable.scala

Selects the first element of this iterable collection.

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

Attributes

Returns: the first element of this iterable collection.
Throws: NoSuchElementException if the iterable collection is empty.
Inherited from:: IterableOps
Source: Iterable.scala

Optionally selects the first element.

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

Attributes

Returns: the first element of this iterable collection if it is nonempty, None if it is empty.
Inherited from:: IterableOps
Source: Iterable.scala

The initial part of the collection without its last element.

Note: Even when applied to a view or a lazy collection it will always force the elements.

Attributes

Inherited from:: IterableOps
Source: Iterable.scala

Iterates over the inits of this iterable collection.

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

Note: Even when applied to a view or a lazy collection it will always force the elements.

Attributes

Returns: an iterator over all the inits of this iterable collection
Example: List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)
Inherited from:: IterableOps
Source: Iterable.scala

Tests whether this iterable collection can be repeatedly traversed.

Tests whether this iterable collection can be repeatedly traversed. Always true for Iterables and false for Iterators unless overridden.

Attributes

Returns: true if it is repeatedly traversable, false otherwise.
Definition Classes: IterableOps -> IterableOnceOps
Inherited from:: IterableOps
Source: Iterable.scala

The companion object of this iterable collection, providing various factory methods.

Attributes

Note: When implementing a custom collection type and refining CC to the new type, this method needs to be overridden to return a factory for the new type (the compiler will issue an error otherwise).
Inherited from:: IterableOps
Source: Iterable.scala

Iterator can be used only once

Attributes

Inherited from:: IterableOnce
Source: IterableOnce.scala

Attributes

Returns: The number of elements in this collection, if it can be cheaply computed, -1 otherwise. Cheaply usually means: Not requiring a collection traversal.
Inherited from:: IterableOnce
Source: IterableOnce.scala

Selects the last element.

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

Attributes

Returns: The last element of this iterable collection.
Throws: NoSuchElementException If the iterable collection is empty.
Inherited from:: IterableOps
Source: Iterable.scala

Optionally selects the last element.

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

Attributes

Returns: the last element of this iterable collection$ if it is nonempty, None if it is empty.
Inherited from:: IterableOps
Source: Iterable.scala

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

Type parameters

B: the element type of the returned iterable collection.

Value parameters

f: the function to apply to each element.

Attributes

Returns: a new iterable collection resulting from applying the given function f to each element of this iterable collection and collecting the results.
Inherited from:: IterableOps
Source: Iterable.scala

Finds the largest element.

Note: will not terminate for infinite-sized collections.

Type parameters

B: The type over which the ordering is defined.

Value parameters

ord: An ordering to be used for comparing elements.

Attributes

Returns: the largest element of this collection with respect to the ordering ord.
Throws: UnsupportedOperationException if this collection is empty.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

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

Note: will not terminate for infinite-sized collections.

Type parameters

B: The result type of the function f.

Value parameters

cmp: An ordering to be used for comparing elements.
f: The measuring function.

Attributes

Returns: the first element of this collection with the largest value measured by function f with respect to the ordering cmp.
Throws: UnsupportedOperationException if this collection is empty.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

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

Note: will not terminate for infinite-sized collections.

Type parameters

B: The result type of the function f.

Value parameters

cmp: An ordering to be used for comparing elements.
f: The measuring function.

Attributes

Returns: an option value containing the first element of this collection with the largest value measured by function f with respect to the ordering cmp.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Finds the largest element.

Note: will not terminate for infinite-sized collections.

Type parameters

B: The type over which the ordering is defined.

Value parameters

ord: An ordering to be used for comparing elements.

Attributes

Returns: an option value containing the largest element of this collection with respect to the ordering ord.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Finds the smallest element.

Note: will not terminate for infinite-sized collections.

Type parameters

B: The type over which the ordering is defined.

Value parameters

ord: An ordering to be used for comparing elements.

Attributes

Returns: the smallest element of this collection with respect to the ordering ord.
Throws: UnsupportedOperationException if this collection is empty.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

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

Note: will not terminate for infinite-sized collections.

Type parameters

B: The result type of the function f.

Value parameters

cmp: An ordering to be used for comparing elements.
f: The measuring function.

Attributes

Returns: the first element of this collection with the smallest value measured by function f with respect to the ordering cmp.
Throws: UnsupportedOperationException if this collection is empty.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

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

Note: will not terminate for infinite-sized collections.

Type parameters

B: The result type of the function f.

Value parameters

cmp: An ordering to be used for comparing elements.
f: The measuring function.

Attributes

Returns: an option value containing the first element of this collection with the smallest value measured by function f with respect to the ordering cmp.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Finds the smallest element.

Note: will not terminate for infinite-sized collections.

Type parameters

B: The type over which the ordering is defined.

Value parameters

ord: An ordering to be used for comparing elements.

Attributes

Returns: an option value containing the smallest element of this collection with respect to the ordering ord.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Displays all elements of this collection in a string.

Delegates to addString, which can be overridden.

Attributes

Returns: a string representation of this collection. In the resulting string the string representations (w.r.t. the method toString) of all elements of this collection follow each other without any separator string.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Displays all elements of this collection in a string using a separator string.

Delegates to addString, which can be overridden.

Value parameters

sep: the separator string.

Attributes

Returns: a string representation of this collection. In the resulting string the string representations (w.r.t. the method toString) of all elements of this collection are separated by the string sep.
Example: List(1, 2, 3).mkString("|") = "1|2|3"
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

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

Delegates to addString, which can be overridden.

Value parameters

end: the ending string.
sep: the separator string.
start: the starting string.

Attributes

Returns: a string representation of this collection. 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 collection are separated by the string sep.
Example: List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Tests whether the collection is not empty.

Attributes

Returns: true if the collection contains at least one element, false otherwise.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

A pair of, first, all elements that satisfy predicate p and, second, all elements that do not.

A pair of, first, all elements that satisfy predicate p and, second, all elements that do not. Interesting because it splits a collection in two.

The default implementation provided here needs to traverse the collection twice. Strict collections have an overridden version of partition in StrictOptimizedIterableOps, which requires only a single traversal.

Attributes

Inherited from:: IterableOps
Source: Iterable.scala

Applies a function f to each element of the iterable collection and returns a pair of iterable collections: the first one made of those values returned by f that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.

Example:

val xs = Iterable(1, "one", 2, "two", 3, "three") partitionMap {
 case i: Int => Left(i)
 case s: String => Right(s)
}
// xs == (Iterable(1, 2, 3),
//        Iterable(one, two, three))

Type parameters

A1: the element type of the first resulting collection
A2: the element type of the second resulting collection

Value parameters

f: the 'split function' mapping the elements of this iterable collection to an scala.util.Either

Attributes

Returns: a pair of iterable collections: the first one made of those values returned by f that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.
Inherited from:: IterableOps
Source: Iterable.scala

Multiplies up the elements of this collection.

Note: will not terminate for infinite-sized collections.

Type parameters

B: the result type of the * operator.

Value parameters

num: an implicit parameter defining a set of numeric operations which includes the * operator to be used in forming the product.

Attributes

Returns: the product of all elements of this collection with respect to the * operator in num.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Reduces the elements of this collection using the specified associative binary operator.

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

Type parameters

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

Value parameters

op: A binary operator that must be associative.

Attributes

Returns: The result of applying reduce operator op between all the elements if the collection is nonempty.
Throws: UnsupportedOperationException if this collection is empty.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Applies a binary operator to all elements of this collection, 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.

Type parameters

B: the result type of the binary operator.

Value parameters

op: the binary operator.

Attributes

Returns: the result of inserting op between consecutive elements of this collection, going left to right: op( op( ... op(x1, x2) ..., xn-1), xn) where x1, ..., xn are the elements of this collection.
Throws: UnsupportedOperationException if this collection is empty.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Optionally applies a binary operator to all elements of this collection, 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.

Type parameters

B: the result type of the binary operator.

Value parameters

op: the binary operator.

Attributes

Returns: an option value containing the result of reduceLeft(op) if this collection is nonempty, None otherwise.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Reduces the elements of this collection, if any, using the specified associative binary operator.

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

Type parameters

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

Value parameters

op: A binary operator that must be associative.

Attributes

Returns: An option value containing result of applying reduce operator op between all the elements if the collection is nonempty, and None otherwise.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Applies a binary operator to all elements of this collection, 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.

Type parameters

B: the result type of the binary operator.

Value parameters

op: the binary operator.

Attributes

Returns: the result of inserting op between consecutive elements of this collection, going right to left: op(x1, op(x2, ..., op(xn-1, xn)...)) where x1, ..., xn are the elements of this collection.
Throws: UnsupportedOperationException if this collection is empty.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Optionally applies a binary operator to all elements of this collection, 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.

Type parameters

B: the result type of the binary operator.

Value parameters

op: the binary operator.

Attributes

Returns: an option value containing the result of reduceRight(op) if this collection is nonempty, None otherwise.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Attributes

Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Computes a prefix scan of the elements of the collection.

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

Type parameters

B: element type of the resulting collection

Value parameters

op: the associative operator for the scan
z: neutral element for the operator op

Attributes

Returns: a new iterable collection containing the prefix scan of the elements in this iterable collection
Inherited from:: IterableOps
Source: Iterable.scala

Produces a iterable collection containing cumulative results of applying the operator going left to right, including the initial value.

Note: will not terminate for infinite-sized collections.

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

Type parameters

B: the type of the elements in the resulting collection

Value parameters

op: the binary operator applied to the intermediate result and the element
z: the initial value

Attributes

Returns: collection with intermediate results
Inherited from:: IterableOps
Source: Iterable.scala

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.

Note: Even when applied to a view or a lazy collection it will always force the elements.

Example:

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

Type parameters

B: the type of the elements in the resulting collection

Value parameters

op: the binary operator applied to the intermediate result and the element
z: the initial value

Attributes

Returns: collection with intermediate results
Inherited from:: IterableOps
Source: Iterable.scala

Returns a value class containing operations for comparing the size of this iterable collection to a test value.

These operations are implemented in terms of sizeCompare(Int), and allow the following more readable usages:

this.sizeIs < size     // this.sizeCompare(size) < 0
this.sizeIs <= size    // this.sizeCompare(size) <= 0
this.sizeIs == size    // this.sizeCompare(size) == 0
this.sizeIs != size    // this.sizeCompare(size) != 0
this.sizeIs >= size    // this.sizeCompare(size) >= 0
this.sizeIs > size     // this.sizeCompare(size) > 0

Attributes

Inherited from:: IterableOps
Source: Iterable.scala

Selects an interval of elements.

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

from <= indexOf(x) < until

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

Value parameters

from: the lowest index to include from this iterable collection.
until: the lowest index to EXCLUDE from this iterable collection.

Attributes

Returns: a iterable collection containing the elements greater than or equal to index from extending up to (but not including) index until of this iterable collection.
Inherited from:: IterableOps
Source: Iterable.scala

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

The returned iterator will be empty when called on an empty collection. The last element the iterator produces may be smaller than the window size when the original collection isn't exhausted by the window before it and its last element isn't skipped by the step before it.

Value parameters

size: the number of elements per group
step: the distance between the first elements of successive groups

Attributes

Returns: An iterator producing iterable collections of size size, except the last element (which may be the only element) will be smaller if there are fewer than size elements remaining to be grouped.
See also: scala.collection.Iterator, method sliding
Example: List(1, 2, 3, 4, 5).sliding(2, 2) = Iterator(List(1, 2), List(3, 4), List(5))

List(1, 2, 3, 4, 5, 6).sliding(2, 3) = Iterator(List(1, 2), List(4, 5))
Inherited from:: IterableOps
Source: Iterable.scala

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

An empty collection returns an empty iterator, and a non-empty collection containing fewer elements than the window size returns an iterator that will produce the original collection as its only element.

Value parameters

size: the number of elements per group

Attributes

Returns: An iterator producing iterable collections of size size, except for a non-empty collection with less than size elements, which returns an iterator that produces the source collection itself as its only element.
See also: scala.collection.Iterator, method sliding
Example: List().sliding(2) = empty iterator

List(1).sliding(2) = Iterator(List(1))

List(1, 2).sliding(2) = Iterator(List(1, 2))

List(1, 2, 3).sliding(2) = Iterator(List(1, 2), List(2, 3))
Inherited from:: IterableOps
Source: Iterable.scala

Splits this iterable collection 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.

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

Value parameters

p: the test predicate

Attributes

Returns: a pair consisting of the longest prefix of this iterable collection whose elements all satisfy p, and the rest of this iterable collection.
Inherited from:: IterableOps
Source: Iterable.scala

Splits this iterable collection into a prefix/suffix pair at a given position.

Note: c splitAt n is equivalent to (but possibly more efficient than) (c take n, c drop n).

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

Value parameters

n: the position at which to split.

Attributes

Returns: a pair of iterable collections consisting of the first n elements of this iterable collection, and the other elements.
Definition Classes: IterableOps -> IterableOnceOps
Inherited from:: IterableOps
Source: Iterable.scala

Returns a scala.collection.Stepper for the elements of this collection.

The Stepper enables creating a Java stream to operate on the collection, see scala.jdk.StreamConverters. For collections holding primitive values, the Stepper can be used as an iterator which doesn't box the elements.

The implicit scala.collection.StepperShape parameter defines the resulting Stepper type according to the element type of this collection.

For collections of Int, Short, Byte or Char, an scala.collection.IntStepper is returned
For collections of Double or Float, a scala.collection.DoubleStepper is returned
For collections of Long a scala.collection.LongStepper is returned
For any other element type, an scala.collection.AnyStepper is returned

Note that this method is overridden in subclasses and the return type is refined to S with EfficientSplit, for example scala.collection.IndexedSeqOps.stepper. For Steppers marked with scala.collection.Stepper.EfficientSplit, the converters in scala.jdk.StreamConverters allow creating parallel streams, whereas bare Steppers can be converted only to sequential streams.

Attributes

Inherited from:: IterableOnce
Source: IterableOnce.scala

Sums up the elements of this collection.

Note: will not terminate for infinite-sized collections.

Type parameters

B: the result type of the + operator.

Value parameters

num: an implicit parameter defining a set of numeric operations which includes the + operator to be used in forming the sum.

Attributes

Returns: the sum of all elements of this collection with respect to the + operator in num.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

The rest of the collection without its first element.

Attributes

Inherited from:: IterableOps
Source: Iterable.scala

Iterates over the tails of this iterable collection.

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

Attributes

Returns: an iterator over all the tails of this iterable collection
Example: List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)
Inherited from:: IterableOps
Source: Iterable.scala

Selects the first n elements.

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

Value parameters

n: the number of elements to take from this iterable collection.

Attributes

Returns: a iterable collection consisting only of the first n elements of this iterable collection, or else the whole iterable collection, if it has less than n elements. If n is negative, returns an empty iterable collection.
Inherited from:: IterableOps
Source: Iterable.scala

Selects the last n elements.

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

Value parameters

n: the number of elements to take from this iterable collection.

Attributes

Returns: a iterable collection consisting only of the last n elements of this iterable collection, or else the whole iterable collection, if it has less than n elements. If n is negative, returns an empty iterable collection.
Inherited from:: IterableOps
Source: Iterable.scala

Takes longest prefix of elements that satisfy a predicate.

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

Value parameters

p: The predicate used to test elements.

Attributes

Returns: the longest prefix of this iterable collection whose elements all satisfy the predicate p.
Inherited from:: IterableOps
Source: Iterable.scala

Applies a side-effecting function to each element in this collection.

Applies a side-effecting function to each element in this collection. Strict collections will apply f to their elements immediately, while lazy collections like Views and LazyLists will only apply f on each element if and when that element is evaluated, and each time that element is evaluated.

Type parameters

U: the return type of f

Value parameters

f: a function to apply to each element in this iterable collection

Attributes

Returns: The same logical collection as this
Definition Classes: IterableOps -> IterableOnceOps
Inherited from:: IterableOps
Source: Iterable.scala

Given a collection factory factory, convert this collection to the appropriate representation for the current element type A.

Given a collection factory factory, convert this collection to the appropriate representation for the current element type A. Example uses:

xs.to(List) xs.to(ArrayBuffer) xs.to(BitSet) // for xs: Iterable[Int]

Attributes

Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Convert collection to array.

Implementation note: DO NOT call Array.from from this method.

Attributes

Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Attributes

Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Attributes

Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Attributes

Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Attributes

Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Attributes

Returns: This collection as a Seq[A]. This is equivalent to to(Seq) but might be faster.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Attributes

Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Attributes

Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Transposes this iterable collection of iterable collections into a iterable collection of iterable collections.

The resulting collection's type will be guided by the static type of iterable collection. For example:

val xs = List(
           Set(1, 2, 3),
           Set(4, 5, 6)).transpose
// xs == List(
//         List(1, 4),
//         List(2, 5),
//         List(3, 6))

val ys = Vector(
           List(1, 2, 3),
           List(4, 5, 6)).transpose
// ys == Vector(
//         Vector(1, 4),
//         Vector(2, 5),
//         Vector(3, 6))

Note: Even when applied to a view or a lazy collection it will always force the elements.

Type parameters

B: the type of the elements of each iterable collection.

Value parameters

asIterable: an implicit conversion which asserts that the element type of this iterable collection is an Iterable.

Attributes

Returns: a two-dimensional iterable collection of iterable collections which has as nth row the nth column of this iterable collection.
Throws: IllegalArgumentException if all collections in this iterable collection are not of the same size.
Inherited from:: IterableOps
Source: Iterable.scala

Converts this iterable collection of pairs into two collections of the first and second half of each pair.

val xs = Iterable(
           (1, "one"),
           (2, "two"),
           (3, "three")).unzip
// xs == (Iterable(1, 2, 3),
//        Iterable(one, two, three))

Type parameters

A1: the type of the first half of the element pairs
A2: the type of the second half of the element pairs

Value parameters

asPair: an implicit conversion which asserts that the element type of this iterable collection is a pair.

Attributes

Returns: a pair of iterable collections, containing the first, respectively second half of each element pair of this iterable collection.
Inherited from:: IterableOps
Source: Iterable.scala

Converts this iterable collection of triples into three collections of the first, second, and third element of each triple.

val xs = Iterable(
           (1, "one", '1'),
           (2, "two", '2'),
           (3, "three", '3')).unzip3
// xs == (Iterable(1, 2, 3),
//        Iterable(one, two, three),
//        Iterable(1, 2, 3))

Type parameters

A1: the type of the first member of the element triples
A2: the type of the second member of the element triples
A3: the type of the third member of the element triples

Value parameters

asTriple: an implicit conversion which asserts that the element type of this iterable collection is a triple.

Attributes

Returns: a triple of iterable collections, containing the first, second, respectively third member of each element triple of this iterable collection.
Inherited from:: IterableOps
Source: Iterable.scala

Creates a non-strict filter of this iterable 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.

Value parameters

p: the predicate used to test elements.

Attributes

Returns: an object of class WithFilter, which supports map, flatMap, foreach, and withFilter operations. All these operations apply to those elements of this iterable collection which satisfy the predicate p.
Inherited from:: IterableOps
Source: Iterable.scala

Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs.

Returns a iterable collection formed from this iterable collection 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.

Type parameters

B: the type of the second half of the returned pairs

Value parameters

that: The iterable providing the second half of each result pair

Attributes

Returns: a new iterable collection containing pairs consisting of corresponding elements of this iterable collection and that. The length of the returned collection is the minimum of the lengths of this iterable collection and that.
Inherited from:: IterableOps
Source: Iterable.scala

Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs.

Returns a iterable collection formed from this iterable collection 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.

Value parameters

that: the iterable providing the second half of each result pair
thatElem: the element to be used to fill up the result if that is shorter than this iterable collection.
thisElem: the element to be used to fill up the result if this iterable collection is shorter than that.

Attributes

Returns: a new collection of type That containing pairs consisting of corresponding elements of this iterable collection and that. The length of the returned collection is the maximum of the lengths of this iterable collection and that. If this iterable collection is shorter than that, thisElem values are used to pad the result. If that is shorter than this iterable collection, thatElem values are used to pad the result.
Inherited from:: IterableOps
Source: Iterable.scala

Zips this iterable collection with its indices.

Attributes

Returns: A new iterable collection containing pairs consisting of all elements of this iterable collection paired with their index. Indices start at 0.
Example: List("a", "b", "c").zipWithIndex == List(("a", 0), ("b", 1), ("c", 2))
Inherited from:: IterableOps
Source: Iterable.scala

Deprecated and Inherited methods

Attributes

Deprecated: true
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Attributes

Deprecated: true
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Attributes

Deprecated: true
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Attributes

Deprecated: true
Inherited from:: IterableOps
Source: Iterable.scala

Attributes

Deprecated: true
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

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

Tests whether this 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.

Attributes

Returns: true if this collection is known to have finite size, false otherwise.
See also: method knownSize for a more useful alternative
Deprecated: This method is deprecated in 2.13 because it does not provide any actionable information. As noted above, even the collection library itself does not use it. When there is no guarantee that a collection is finite, it is generally best to attempt a computation anyway and document that it will not terminate for infinite collections rather than backing out because this would prevent performing the computation on collections that are in fact finite even though hasDefiniteSize returns false.
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Attributes

Deprecated: true
Inherited from:: IterableOps
Source: Iterable.scala

Attributes

Returns: This collection as an Iterable[A]. No new collection will be built if this is already an Iterable[A].
Deprecated: true
Inherited from:: IterableOps
Source: Iterable.scala

Attributes

Deprecated: true
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Attributes

Deprecated: true
Inherited from:: IterableOnceOps
Source: IterableOnce.scala

Converts this iterable collection to an unspecified Iterable.

Converts this iterable collection to an unspecified Iterable. Will return the same collection if this instance is already Iterable.

Attributes

Returns: An Iterable containing all elements of this iterable collection.
Deprecated: true
Inherited from:: IterableOps
Source: Iterable.scala

A view over a slice of the elements of this collection.

Attributes

Deprecated: true
Inherited from:: IterableOps
Source: Iterable.scala

In this article

Generated with