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

Selects all elements except the first n ones.

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

Selects all elements except the longest prefix that satisfies a predicate.

The matching prefix starts with the first element of this collection, and the element following the prefix is the first element that does not satisfy the predicate. The matching prefix may be empty, so that this method returns the entire collection.

Example:

scala> List(1, 2, 3, 100, 4).dropWhile(n => n < 10)
val res0: List[Int] = List(100, 4)

scala> List(1, 2, 3, 100, 4).dropWhile(n => n == 0)
val res1: List[Int] = List(1, 2, 3, 100, 4)

Use span to obtain both the prefix and suffix. Use filterNot to drop all elements that satisfy the predicate.

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

Selects all elements of this collection which satisfy a predicate.

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

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

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

The resulting collection's type will be guided by the type of 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)

Returns the runtime class representation of the object.

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

Produces a 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.

Selects an interval of elements. The returned 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.

Splits this 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.

Selects the first n elements.

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

Selects the longest prefix of elements that satisfy a predicate.

The matching prefix starts with the first element of this collection, and the element following the prefix is the first element that does not satisfy the predicate. The matching prefix may empty, so that this method returns an empty collection.

Example:

scala> List(1, 2, 3, 100, 4).takeWhile(n => n < 10)
val res0: List[Int] = List(1, 2, 3)

scala> List(1, 2, 3, 100, 4).takeWhile(n => n == 0)
val res1: List[Int] = List()

Use span to obtain both the prefix and suffix. Use filter to retain only those elements from the entire collection that satisfy the predicate.

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

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.

Zips this collection with its indices.

Test two objects for inequality.

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.

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

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

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

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)

Forces the compiler to treat the receiver object as having type T0, even though doing so may violate type safety.

This method is useful when you believe you have type information the compiler doesn't, and it also isn't possible to check the type at runtime. In such situations, skipping type safety is the only option.

It is platform dependent whether asInstanceOf has any effect at runtime. It might do a runtime type test on the erasure of T0, insert a conversion (such as boxing/unboxing), fill in a default value, or do nothing at all.

In particular, asInstanceOf is not a type test. It does **not** mean:

this match {
 case x: T0 => x
 case _     => throw ClassCastException("...")

Use pattern matching or isInstanceOf for type testing instead.

Situations where asInstanceOf is useful:

• when flow analysis fails to deduce T0 automatically
• when down-casting a type parameter or an abstract type member (which cannot be checked at runtime due to type erasure) If there is any doubt and you are able to type test instead, you should do so.

Be careful of using asInstanceOf when T0 is a primitive type. When T0 is primitive, asInstanceOf may insert a conversion instead of a type test. If your intent is to convert, use a toT method (x.toChar, x.toByte, etc.).

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.

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.

Copies 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.

Copies 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.

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.

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

Note: will not terminate for infinite-sized collections.

Compares the receiver object (this) with the argument object (that) for equivalence.

Any implementation of this method should be an equivalence relation:

• It is reflexive: for any instance x of type Any, x.equals(x) should return true.
• It is symmetric: for any instances x and y of type Any, x.equals(y) should return true if and only if y.equals(x) returns true.
• It is transitive: for any instances x, y, and z of type Any if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.

If you override this method, you should verify that your implementation remains an equivalence relation. Additionally, when overriding this method it is usually necessary to override hashCode to ensure that objects which are "equal" (o1.equals(o2) returns true) hash to the same scala.Int. (o1.hashCode.equals(o2.hashCode)).

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

Note: may not terminate for infinite-sized collections.

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.

Applies the given binary operator op to the given initial value z and all elements of this collection.

For each application of the operator, each operand is either an element of this collection, the initial value, or another such application of the operator.

The order of applications of the operator is unspecified and may be nondeterministic. Each element appears exactly once in the computation. The initial value may be used an arbitrary number of times, but at least once.

If this collection is ordered, then for any application of the operator, the element(s) appearing in the left operand will precede those in the right.

Note: might return different results for different runs, unless either of the following conditions is met: (1) the operator is associative, and the underlying collection type is ordered; or (2) the operator is associative and commutative. In either case, it is also necessary that the initial value be a neutral value for the operator, e.g. Nil for List concatenation or 1 for multiplication.

The default implementation in IterableOnce is equivalent to foldLeft but may be overridden for more efficient traversal orders.

Note: will not terminate for infinite-sized collections.

Applies the given binary operator op to the given initial value z and all elements of this collection, going left to right. Returns the initial value if this collection is empty.

"Going left to right" only makes sense if this collection is ordered: then if x1, x2, ..., xn are the elements of this collection, the result is op( op( ... op( op(z, x1), x2) ... ), xn).

If this collection is not ordered, then for each application of the operator, each right operand is an element. In addition, the leftmost operand is the initial value, and each other left operand is itself an application of the operator. The elements of this collection and the initial value all appear exactly once in the computation.

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

Note: will not terminate for infinite-sized collections.

Applies the given binary operator op to all elements of this collection and the given initial value z, going right to left. Returns the initial value if this collection is empty.

"Going right to left" only makes sense if this collection is ordered: then if x1, x2, ..., xn are the elements of this collection, the result is op(x1, op(x2, op( ... op(xn, z) ... ))).

If this collection is not ordered, then for each application of the operator, each left operand is an element. In addition, the rightmost operand is the initial value, and each other right operand is itself an application of the operator. The elements of this collection and the initial value all appear exactly once in the computation.

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

Note: will not terminate for infinite-sized collections.

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

Note: may not terminate for infinite-sized collections.

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

Calculate a hash code value for the object.

The default hashing algorithm is platform dependent.

Note that it is allowed for two objects to have identical hash codes (o1.hashCode.equals(o2.hashCode)) yet not be equal (o1.equals(o2) returns false). A degenerate implementation could always return 0. However, it is required that if two objects are equal (o1.equals(o2) returns true) that they have identical hash codes (o1.hashCode.equals(o2.hashCode)). Therefore, when overriding this method, be sure to verify that the behavior is consistent with the equals method.

Tests whether the collection is empty.

Note: The default implementation creates and discards an iterator.

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

Test whether the dynamic type of the receiver object has the same erasure as T0.

Depending on what T0 is, the test is done in one of the below ways:

• T0 is a non-parameterized class type, e.g. BigDecimal: this method returns true if the value of the receiver object is a BigDecimal or a subtype of BigDecimal.
• T0 is a parameterized class type, e.g. List[Int]: this method returns true if the value of the receiver object is some List[X] for any X. For example, List(1, 2, 3).isInstanceOf[List[String]] will return true.
• T0 is some singleton type x.type or literal x: this method returns this.eq(x). For example, x.isInstanceOf[1] is equivalent to x.eq(1)
• T0 is an intersection X with Y or X & Y: this method is equivalent to x.isInstanceOf[X] && x.isInstanceOf[Y]
• T0 is a union X | Y: this method is equivalent to x.isInstanceOf[X] || x.isInstanceOf[Y]
• T0 is a type parameter or an abstract type member: this method is equivalent to isInstanceOf[U] where U is T0's upper bound, Any if T0 is unbounded. For example, x.isInstanceOf[A] where A is an unbounded type parameter will return true for any value of x.

This is exactly equivalent to the type pattern _: T0

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

Finds the largest element.

Note: will not terminate for infinite-sized collections.

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

Note: will not terminate for infinite-sized collections.

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

Note: will not terminate for infinite-sized collections.

Finds the largest element.

Note: will not terminate for infinite-sized collections.

Finds the smallest element.

Note: will not terminate for infinite-sized collections.

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

Note: will not terminate for infinite-sized collections.

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

Note: will not terminate for infinite-sized collections.

Finds the smallest element.

Note: will not terminate for infinite-sized collections.

Displays all elements of this collection in a string.

Delegates to addString, which can be overridden.

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

Delegates to addString, which can be overridden.

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

Delegates to addString, which can be overridden.

Tests whether the collection is not empty.

Multiplies together the elements of this collection.

The default implementation uses reduce for a known non-empty collection, foldLeft otherwise.

Note: will not terminate for infinite-sized collections.

Applies the given binary operator op to all elements of this collection.

For each application of the operator, each operand is either an element of this collection or another such application of the operator. The order of applications of the operator is unspecified and may be nondeterministic. Each element appears exactly once in the computation.

If this collection is ordered, then for any application of the operator, the element(s) appearing in the left operand will precede those in the right.

Note: might return different results for different runs, unless either of the following conditions is met: (1) the operator is associative, and the underlying collection type is ordered; or (2) the operator is associative and commutative.

Note: will not terminate for infinite-sized collections.

Applies the given binary operator op to all elements of this collection, going left to right.

"Going left to right" only makes sense if this collection is ordered: then if x1, x2, ..., xn are the elements of this collection, the result is op( op( op( ... op(x1, x2) ... ), xn-1), xn).

If this collection is not ordered, then for each application of the operator, each right operand is an element. In addition, the leftmost operand is the first element of this collection and each other left operand is itself an application of the operator. Each element appears exactly once in the computation.

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

Note: will not terminate for infinite-sized collections.

If this collection is nonempty, reduces it with the given binary operator op, going left to right.

The behavior is the same as reduceLeft except that the value is None if the collection is empty. Each element appears exactly once in the computation.

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

Note: will not terminate for infinite-sized collections.

If this collection is nonempty, reduces it with the given binary operator op.

The behavior is the same as reduce except that the value is None if the collection is empty. The order of applications of the operator is unspecified and may be nondeterministic. Each element appears exactly once in the computation.

Note: might return different results for different runs, unless either of the following conditions is met: (1) the operator is associative, and the underlying collection type is ordered; or (2) the operator is associative and commutative.

Note: will not terminate for infinite-sized collections.

Applies the given binary operator op to all elements of this collection, going right to left.

"Going right to left" only makes sense if this collection is ordered: then if x1, x2, ..., xn are the elements of this collection, the result is op(x1, op(x2, op( ... op(xn-1, xn) ... ))).

If this collection is not ordered, then for each application of the operator, each left operand is an element. In addition, the rightmost operand is the last element of this collection and each other right operand is itself an application of the operator. Each element appears exactly once in the computation.

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

Note: will not terminate for infinite-sized collections.

If this collection is nonempty, reduces it with the given binary operator op, going right to left.

The behavior is the same as reduceRight except that the value is None if the collection is empty. Each element appears exactly once in the computation.

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

Note: will not terminate for infinite-sized collections.

The size of this collection.

Note: will not terminate for infinite-sized collections.

Splits this 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.

Sums the elements of this collection.

The default implementation uses reduce for a known non-empty collection, foldLeft otherwise.

Note: will not terminate for infinite-sized collections.

Given a collection factory factory, converts 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]

Converts this collection to an Array.

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

Converts this collection to a Buffer.

Converts this collection to an IndexedSeq.

Converts this collection to a List.

Converts this collection to a Map, given an implicit coercion from the collection's type to a key-value tuple.

Converts this collection to a Set.

Returns a string representation of the object.

The default representation is platform dependent.

Converts this collection to a Vector.

Aggregates the results of applying an operator to subsequent elements.

Since this method degenerates to foldLeft for sequential (non-parallel) collections, where the combining operation is ignored, it is advisable to prefer foldLeft for that case.

For parallel collections, use the aggregate method specified by scala.collection.parallel.ParIterableLike.

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

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.