# GenSeq

#### trait GenSeq[+A] extends GenSeqLike[A, GenSeq[A]] with GenIterable[A] with Equals with GenericTraversableTemplate[A, GenSeq]

A trait for all sequences which may possibly have their operations implemented in parallel.

Source
GenSeq.scala
Since

2.9

Linear Supertypes
Ordering
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Inherited
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1. GenSeq
2. GenIterable
3. GenTraversable
4. GenericTraversableTemplate
5. HasNewBuilder
6. GenSeqLike
7. Equals
8. GenIterableLike
9. GenTraversableLike
10. Parallelizable
11. GenTraversableOnce
12. AnyRef
13. Any
Visibility
1. Public
2. All

### Abstract Value Members

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

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

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

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

Examples:

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

```     scala> val a = LinkedList(1,2,3,4)

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

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

Note: will not terminate for infinite-sized collections.

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

B

the result type of the binary operator.

z

the start value.

op

the binary operator.

returns

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

```            op(...op(op(z, x1), x2), ..., xn)
```

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

Definition Classes
GenTraversableOnce
2. #### abstract def :\[B](z: B)(op: (A, B) ⇒ B): B

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

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

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

Note: will not terminate for infinite-sized collections.

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

Examples:

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

```     scala> val a = LinkedList(1,2,3,4)

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

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

```
B

the result type of the binary operator.

z

the start value

op

the binary operator

returns

the result of inserting `op` between consecutive elements of this 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.

Definition Classes
GenTraversableOnce
3. #### abstract def aggregate[B](z: B)(seqop: (B, A) ⇒ B, combop: (B, B) ⇒ B): B

Aggregates the results of applying an operator to subsequent elements.

Aggregates the results of applying an operator to subsequent elements.

This is a more general form of `fold` and `reduce`. It has similar semantics, but does not require the result to be a supertype of the element type. It traverses the elements in different partitions sequentially, using `seqop` to update the result, and then applies `combop` to results from different partitions. The implementation of this operation may operate on an arbitrary number of collection partitions, so `combop` may be invoked an arbitrary number of times.

For example, one might want to process some elements and then produce a `Set`. In this case, `seqop` would process an element and append it to the list, while `combop` would concatenate two lists from different partitions together. The initial value `z` would be an empty set.

```   pc.aggregate(Set[Int]())(_ += process(_), _ ++ _)
```

Another example is calculating geometric mean from a collection of doubles (one would typically require big doubles for this).

B

the type of accumulated results

z

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

seqop

an operator used to accumulate results within a partition

combop

an associative operator used to combine results from different partitions

Definition Classes
GenTraversableOnce
4. #### abstract def apply(idx: Int): A

Selects an element by its index in the collection.

Selects an element by its index in the collection.

Example:

```   scala> val x = LinkedList(1, 2, 3, 4, 5)

scala> x(3)
res1: Int = 4
```
idx

The index to select.

returns

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

Definition Classes
GenSeqLike
Exceptions thrown
`IndexOutOfBoundsException`

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

5. #### abstract def canEqual(that: Any): Boolean

A method that should be called from every well-designed equals method that is open to be overridden in a subclass.

A method that should be called from every well-designed equals method that is open to be overridden in a subclass. See Programming in Scala, Chapter 28 for discussion and design.

that

the value being probed for possible equality

returns

true if this instance can possibly equal `that`, otherwise false

Definition Classes
Equals
6. #### abstract def copyToArray[B >: A](xs: Array[B], start: Int, len: Int): Unit

Definition Classes
GenTraversableOnce
7. #### abstract def corresponds[B](that: GenSeq[B])(p: (A, B) ⇒ Boolean): Boolean

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

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

B

the type of the elements of `that`

that

the other sequence

p

the test predicate, which relates elements from both sequences

returns

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

Definition Classes
GenSeqLike
8. #### abstract def count(p: (A) ⇒ Boolean): Int

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

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

p

the predicate used to test elements.

returns

the number of elements satisfying the predicate `p`.

Definition Classes
GenTraversableOnce
9. #### abstract def distinct: GenSeq[A]

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

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

Note: will not terminate for infinite-sized collections.

returns

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

Definition Classes
GenSeqLike
10. #### abstract def drop(n: Int): GenSeq[A]

Selects all elements except first n ones.

Selects all elements except first n ones.

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

n

the number of elements to drop from this collection.

returns

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

Definition Classes
GenTraversableLike
11. #### abstract def dropWhile(pred: (A) ⇒ Boolean): GenSeq[A]

Drops longest prefix of elements that satisfy a predicate.

Drops longest prefix of elements that satisfy a predicate.

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

returns

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

Definition Classes
GenTraversableLike
12. #### abstract def endsWith[B](that: GenSeq[B]): Boolean

Tests whether this collection ends with the given sequence.

Tests whether this collection ends with the given sequence.

Note: will not terminate for infinite-sized collections.

that

the sequence to test

returns

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

Definition Classes
GenSeqLike
13. #### abstract def exists(pred: (A) ⇒ Boolean): Boolean

Definition Classes
GenTraversableOnce
14. #### abstract def filter(pred: (A) ⇒ Boolean): GenSeq[A]

Selects all elements of this collection which satisfy a predicate.

Selects all elements of this collection which satisfy a predicate.

returns

a new collection consisting of all elements of this collection that satisfy the given predicate `p`. Their order may not be preserved.

Definition Classes
GenTraversableLike
15. #### abstract def filterNot(pred: (A) ⇒ Boolean): GenSeq[A]

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

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

returns

a new collection consisting of all elements of this collection that do not satisfy the given predicate `p`. Their order may not be preserved.

Definition Classes
GenTraversableLike
16. #### abstract def find(pred: (A) ⇒ Boolean): Option[A]

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

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.

returns

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

Definition Classes
GenTraversableOnce
17. #### abstract def fold[A1 >: A](z: A1)(op: (A1, A1) ⇒ A1): A1

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

A1

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

z

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

op

a binary operator that must be associative

returns

the result of applying fold operator `op` between all the elements and `z`

Definition Classes
GenTraversableOnce
18. #### abstract def foldLeft[B](z: B)(op: (B, A) ⇒ B): B

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

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.

B

the result type of the binary operator.

z

the start value.

op

the binary operator.

returns

the result of inserting `op` between consecutive elements of this 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.

Definition Classes
GenTraversableOnce
19. #### abstract def foldRight[B](z: B)(op: (A, B) ⇒ B): B

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

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.

B

the result type of the binary operator.

z

the start value.

op

the binary operator.

returns

the result of inserting `op` between consecutive elements of this 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.

Definition Classes
GenTraversableOnce
20. #### abstract def forall(pred: (A) ⇒ Boolean): Boolean

Definition Classes
GenTraversableOnce
21. #### abstract def groupBy[K](f: (A) ⇒ K): GenMap[K, GenSeq[A]]

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

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

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

K

the type of keys returned by the discriminator function.

f

the discriminator function.

returns

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

```                (xs partition f)(k) = xs filter (x => f(x) == k)
```

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

Definition Classes
GenTraversableLike
22. #### abstract def hasDefiniteSize: Boolean

Definition Classes
GenTraversableOnce
23. #### abstract def indexWhere(p: (A) ⇒ Boolean, from: Int): Int

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

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

Note: may not terminate for infinite-sized collections.

p

the predicate used to test elements.

from

the start index

returns

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

Definition Classes
GenSeqLike
24. #### abstract def iterator: Iterator[A]

Definition Classes
GenIterableLike
25. #### abstract def lastIndexWhere(p: (A) ⇒ Boolean, end: Int): Int

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

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

p

the predicate used to test elements.

returns

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

Definition Classes
GenSeqLike
26. #### abstract def length: Int

The length of the collection.

The length of the collection.

Note: will not terminate for infinite-sized collections.

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

returns

the number of elements in this collection.

Definition Classes
GenSeqLike
27. #### abstract def maxBy[B](f: (A) ⇒ B)(implicit cmp: Ordering[B]): A

Definition Classes
GenTraversableOnce
28. #### abstract def minBy[B](f: (A) ⇒ B)(implicit cmp: Ordering[B]): A

Definition Classes
GenTraversableOnce
29. #### abstract def mkString: String

Displays all elements of this collection in a string.

Displays all elements of this collection in a string.

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.

Definition Classes
GenTraversableOnce
30. #### abstract def mkString(sep: String): String

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

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

sep

the separator string.

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`.

Definition Classes
GenTraversableOnce
Example:
1. `List(1, 2, 3).mkString("|") = "1|2|3"`

31. #### abstract def mkString(start: String, sep: String, end: String): String

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

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

start

the starting string.

sep

the separator string.

end

the ending string.

returns

a string representation of this 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`.

Definition Classes
GenTraversableOnce
Example:
1. `List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"`

32. #### abstract def nonEmpty: Boolean

Tests whether the collection is not empty.

Tests whether the collection is not empty.

returns

`true` if the collection contains at least one element, `false` otherwise.

Definition Classes
GenTraversableOnce
33. #### abstract def parCombiner: Combiner[A, ParSeq[A]]

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

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

returns

a combiner for the parallel collection of type `ParRepr`

Attributes
protected[this]
Definition Classes
Parallelizable
34. #### abstract def partition(pred: (A) ⇒ Boolean): (GenSeq[A], GenSeq[A])

Partitions this collection in two collections according to a predicate.

Partitions this collection in two collections according to a predicate.

returns

a pair of collections: the first collection consists of all elements that satisfy the predicate `p` and the second collection consists of all elements that don't. The relative order of the elements in the resulting collections may not be preserved.

Definition Classes
GenTraversableLike
35. #### abstract def reduce[A1 >: A](op: (A1, A1) ⇒ A1): A1

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

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.

A1

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

op

A binary operator that must be associative.

returns

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

Definition Classes
GenTraversableOnce
Exceptions thrown
UnsupportedOperationException

if this collection is empty.

36. #### abstract def reduceLeftOption[B >: A](op: (B, A) ⇒ B): Option[B]

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

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.

B

the result type of the binary operator.

op

the binary operator.

returns

an option value containing the result of `reduceLeft(op)` is this collection is nonempty, `None` otherwise.

Definition Classes
GenTraversableOnce
37. #### abstract def reduceOption[A1 >: A](op: (A1, A1) ⇒ A1): Option[A1]

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

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.

A1

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

op

A binary operator that must be associative.

returns

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

Definition Classes
GenTraversableOnce
38. #### abstract def reduceRight[B >: A](op: (A, B) ⇒ B): B

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

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.

B

the result type of the binary operator.

op

the binary operator.

returns

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

```            op(x,,1,,, op(x,,2,,, ..., op(x,,n-1,,, x,,n,,)...))
```

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

Definition Classes
GenTraversableOnce
Exceptions thrown
`UnsupportedOperationException`

if this collection is empty.

39. #### abstract def reduceRightOption[B >: A](op: (A, B) ⇒ B): Option[B]

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

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.

B

the result type of the binary operator.

op

the binary operator.

returns

an option value containing the result of `reduceRight(op)` is this collection is nonempty, `None` otherwise.

Definition Classes
GenTraversableOnce
40. #### abstract def repr: GenSeq[A]

Definition Classes
GenTraversableLike
41. #### abstract def reverse: GenSeq[A]

Returns new collection wih elements in reversed order.

Returns new collection wih elements in reversed order.

Note: will not terminate for infinite-sized collections.

returns

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

Definition Classes
GenSeqLike
42. #### abstract def scan[B >: A, That](z: B)(op: (B, B) ⇒ B)(implicit cbf: CanBuildFrom[GenSeq[A], B, That]): That

Computes a prefix scan of the elements of the collection.

Computes a prefix scan of the elements of the collection.

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

B

element type of the resulting collection

That

type of the resulting collection

z

neutral element for the operator `op`

op

the associative operator for the scan

cbf

combiner factory which provides a combiner

returns

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

Definition Classes
GenTraversableLike
43. #### abstract def scanLeft[B, That](z: B)(op: (B, A) ⇒ B)(implicit bf: CanBuildFrom[GenSeq[A], B, That]): That

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

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

Note: will not terminate for infinite-sized collections.

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

B

the type of the elements in the resulting collection

That

the actual type of the resulting collection

z

the initial value

op

the binary operator applied to the intermediate result and the element

bf

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

returns

collection with intermediate results

Definition Classes
GenTraversableLike
44. #### abstract def scanRight[B, That](z: B)(op: (A, B) ⇒ B)(implicit bf: CanBuildFrom[GenSeq[A], B, That]): That

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

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

Note: will not terminate for infinite-sized collections.

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

Example:

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

the type of the elements in the resulting collection

That

the actual type of the resulting collection

z

the initial value

op

the binary operator applied to the intermediate result and the element

bf

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

returns

collection with intermediate results

Definition Classes
GenTraversableLike
Annotations
@migration
Migration

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

45. #### abstract def segmentLength(p: (A) ⇒ Boolean, from: Int): Int

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

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

Note: may not terminate for infinite-sized collections.

p

the predicate used to test elements.

from

the index where the search starts.

returns

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

Definition Classes
GenSeqLike

47. #### abstract def size: Int

The size of this collection.

The size of this collection.

Note: will not terminate for infinite-sized collections.

returns

the number of elements in this collection.

Definition Classes
GenTraversableLikeGenTraversableOnce
48. #### abstract def slice(unc_from: Int, unc_until: Int): GenSeq[A]

Selects an interval of elements.

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

```   from <= indexOf(x) < until
```

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

returns

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

Definition Classes
GenTraversableLike
49. #### abstract def span(pred: (A) ⇒ Boolean): (GenSeq[A], GenSeq[A])

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

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.

returns

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

Definition Classes
GenTraversableLike
50. #### abstract def splitAt(n: Int): (GenSeq[A], GenSeq[A])

Splits this collection into two at a given position.

Splits this collection into two 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.

n

the position at which to split.

returns

a pair of collections consisting of the first `n` elements of this collection, and the other elements.

Definition Classes
GenTraversableLike
51. #### abstract def startsWith[B](that: GenSeq[B], offset: Int): Boolean

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

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

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

that

the sequence to test

offset

the index where the sequence is searched.

returns

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

Definition Classes
GenSeqLike
52. #### abstract def stringPrefix: String

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

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

returns

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

Definition Classes
GenTraversableLike
53. #### abstract def take(n: Int): GenSeq[A]

Selects first n elements.

Selects first n elements.

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

n

Tt number of elements to take from this collection.

returns

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

Definition Classes
GenTraversableLike
54. #### abstract def takeWhile(pred: (A) ⇒ Boolean): GenSeq[A]

Takes longest prefix of elements that satisfy a predicate.

Takes longest prefix of elements that satisfy a predicate.

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

returns

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

Definition Classes
GenTraversableLike
55. #### abstract def toBuffer[A1 >: A]: Buffer[A1]

Converts this collection to a mutable buffer.

Converts this collection to a mutable buffer.

Note: will not terminate for infinite-sized collections.

returns

a buffer containing all elements of this collection.

Definition Classes
GenTraversableOnce
56. #### abstract def toIndexedSeq: IndexedSeq[A]

Converts this collection to an indexed sequence.

Converts this collection to an indexed sequence.

Note: will not terminate for infinite-sized collections.

returns

an indexed sequence containing all elements of this collection.

Definition Classes
GenTraversableOnce
57. #### abstract def toIterable: GenIterable[A]

Converts this collection to an iterable collection.

Converts this collection to an iterable collection. Note that the choice of target `Iterable` is lazy in this default implementation as this `TraversableOnce` may be lazy and unevaluated (i.e. it may be an iterator which is only traversable once).

Note: will not terminate for infinite-sized collections.

returns

an `Iterable` containing all elements of this collection.

Definition Classes
GenTraversableOnce
58. #### abstract def toIterator: Iterator[A]

Returns an Iterator over the elements in this collection.

Returns an Iterator over the elements in this collection. Will return the same Iterator if this instance is already an Iterator.

Note: will not terminate for infinite-sized collections.

returns

an Iterator containing all elements of this collection.

Definition Classes
GenTraversableOnce
59. #### abstract def toList: List[A]

Converts this collection to a list.

Converts this collection to a list.

Note: will not terminate for infinite-sized collections.

returns

a list containing all elements of this collection.

Definition Classes
GenTraversableOnce
60. #### abstract def toSeq: GenSeq[A]

Converts this collection to a sequence.

Converts this collection to a sequence. As with `toIterable`, it's lazy in this default implementation, as this `TraversableOnce` may be lazy and unevaluated.

Note: will not terminate for infinite-sized collections.

returns

a sequence containing all elements of this collection.

Definition Classes
GenSeqLikeGenTraversableOnce
61. #### abstract def toSet[A1 >: A]: GenSet[A1]

Converts this collection to a set.

Converts this collection to a set.

Note: will not terminate for infinite-sized collections.

returns

a set containing all elements of this collection.

Definition Classes
GenTraversableOnce
62. #### abstract def toStream: Stream[A]

Converts this collection to a stream.

Converts this collection to a stream.

Note: will not terminate for infinite-sized collections.

returns

a stream containing all elements of this collection.

Definition Classes
GenTraversableOnce
63. #### abstract def toTraversable: GenTraversable[A]

Converts this collection to an unspecified Traversable.

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

Note: will not terminate for infinite-sized collections.

returns

a Traversable containing all elements of this collection.

Definition Classes
GenTraversableOnce

### Concrete Value Members

1. #### final def !=(arg0: AnyRef): Boolean

Definition Classes
AnyRef
2. #### final def !=(arg0: Any): Boolean

Test two objects for inequality.

Test two objects for inequality.

returns

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

Definition Classes
Any
3. #### final def ##(): Int

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

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

returns

a hash value consistent with ==

Definition Classes
AnyRef → Any
4. #### abstract def ++[B](that: GenTraversableOnce[B]): CC[B]

[use case]

[use case]
B

the element type of the returned collection.

that

the traversable to append.

returns

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

Definition Classes
GenTraversableLike
5. #### abstract def +:(elem: A): CC[A]

[use case]

[use case]
elem

the prepended element

returns

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

Definition Classes
GenSeqLike
6. #### def /:\[A1 >: A](z: A1)(op: (A1, A1) ⇒ A1): A1

A syntactic sugar for out of order folding.

A syntactic sugar for out of order folding. See `fold`.

Example:

```     scala> val a = LinkedList(1,2,3,4)

scala> val b = (a /:\ 5)(_+_)
b: Int = 15
```
Definition Classes
GenTraversableOnce
7. #### abstract def :+(elem: A): CC[A]

[use case]

[use case]
elem

the appended element

returns

a new collection consisting of all elements of this collection followed by `elem`. @example

```      scala> import scala.collection.mutable.LinkedList

scala> val b = a :+ 2

scala> println(a)
```
Definition Classes
GenSeqLike
8. #### final def ==(arg0: AnyRef): Boolean

Definition Classes
AnyRef
9. #### final def ==(arg0: Any): Boolean

Test two objects for equality.

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

returns

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

Definition Classes
Any
10. #### final def asInstanceOf[T0]: T0

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

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

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

returns

Definition Classes
Any
Exceptions thrown
ClassCastException

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

11. #### def clone(): AnyRef

Create a copy of the receiver object.

Create a copy of the receiver object.

The default implementation of the `clone` method is platform dependent.

returns

a copy of the receiver object.

Attributes
protected[lang]
Definition Classes
AnyRef
Annotations
()
Note

not specified by SLS as a member of AnyRef

12. #### abstract def collect[B](pf: PartialFunction[A, B]): CC[B]

[use case]

[use case]
B

the element type of the returned collection.

pf

the partial function which filters and maps the collection.

returns

a new 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.

Definition Classes
GenTraversableLike
13. #### def companion: GenericCompanion[GenSeq]

The factory companion object that builds instances of class CC.

The factory companion object that builds instances of class CC. (or its `Iterable` superclass where class CC is not a `Seq`.)

Definition Classes
GenSeqGenIterableGenTraversableGenericTraversableTemplate
14. #### abstract def copyToArray(xs: Array[A], start: Int): Unit

[use case]

[use case]
xs

the array to fill.

start

the starting index.

Definition Classes
GenTraversableOnce
15. #### abstract def copyToArray(xs: Array[A]): Unit

[use case]

[use case]
xs

the array to fill.

Definition Classes
GenTraversableOnce
16. #### abstract def diff(that: GenSeq[A]): CC[A]

[use case]

[use case]
that

the sequence of elements to remove

returns

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

Definition Classes
GenSeqLike
17. #### final def eq(arg0: AnyRef): Boolean

Tests whether the argument (`arg0`) is a reference to the receiver object (`this`).

Tests whether the argument (`arg0`) is a reference to the receiver object (`this`).

The `eq` method implements an equivalence relation on non-null instances of `AnyRef`, and has three additional properties:

• It is consistent: for any non-null instances `x` and `y` of type `AnyRef`, multiple invocations of `x.eq(y)` consistently returns `true` or consistently returns `false`.
• For any non-null instance `x` of type `AnyRef`, `x.eq(null)` and `null.eq(x)` returns `false`.
• `null.eq(null)` returns `true`.

When overriding the `equals` or `hashCode` methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (`o1 eq o2`), they should be equal to each other (`o1 == o2`) and they should hash to the same value (`o1.hashCode == o2.hashCode`).

returns

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

Definition Classes
AnyRef
18. #### def equals(that: Any): Boolean

The equals method for arbitrary sequences.

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

that

The object to compare the sequence to

returns

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

Definition Classes
GenSeqLikeEquals → AnyRef → Any
19. #### def finalize(): Unit

Called by the garbage collector on the receiver object when there are no more references to the object.

Called by the garbage collector on the receiver object when there are no more references to the object.

The details of when and if the `finalize` method is invoked, as well as the interaction between `finalize` and non-local returns and exceptions, are all platform dependent.

Attributes
protected[lang]
Definition Classes
AnyRef
Annotations
()
Note

not specified by SLS as a member of AnyRef

20. #### abstract def flatMap[B](f: (A) ⇒ GenTraversableOnce[B]): CC[B]

[use case]

[use case]
B

the element type of the returned collection.

f

the function to apply to each element.

returns

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

Definition Classes
GenTraversableLike
21. #### def flatten[B]: CC[B]

[use case]

[use case]
B

the type of the elements of each traversable collection.

returns

a new collection resulting from concatenating all element collections.

Definition Classes
GenericTraversableTemplate
22. #### abstract def foreach(f: (A) ⇒ Unit): Unit

[use case]

[use case]
f

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

Definition Classes
GenericTraversableTemplate
23. #### def genericBuilder[B]: Builder[B, GenSeq[B]]

The generic builder that builds instances of CC at arbitrary element types.

The generic builder that builds instances of CC at arbitrary element types.

Definition Classes
GenericTraversableTemplate
24. #### final def getClass(): Class[_]

A representation that corresponds to the dynamic class of the receiver object.

A representation that corresponds to the dynamic class of the receiver object.

The nature of the representation is platform dependent.

returns

a representation that corresponds to the dynamic class of the receiver object.

Definition Classes
AnyRef → Any
Note

not specified by SLS as a member of AnyRef

25. #### def hashCode(): Int

Hashcodes for CC produce a value from the hashcodes of all the elements of the collection.

Hashcodes for CC produce a value from the hashcodes of all the elements of the collection.

returns

the hash code value for this object.

Definition Classes
GenSeqLike → AnyRef → Any

Definition Classes
GenIterableLikeGenTraversableLike
27. #### def indexOf(elem: A, from: Int): Int

[use case]

[use case]
elem

the element value to search for.

from

the start index

returns

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

Definition Classes
GenSeqLike
28. #### def indexOf(elem: A): Int

[use case]

[use case]
elem

the element value to search for.

returns

the index of the first element of this collection that is equal (wrt `==`) to `elem`, or `-1`, if none exists.

Definition Classes
GenSeqLike
29. #### def indexWhere(p: (A) ⇒ Boolean): Int

Finds index of first element satisfying some predicate.

Finds index of first element satisfying some predicate.

Note: may not terminate for infinite-sized collections.

p

the predicate used to test elements.

returns

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

Definition Classes
GenSeqLike
30. #### abstract def intersect(that: GenSeq[A]): CC[A]

[use case]

[use case]
that

the sequence of elements to intersect with.

returns

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

Definition Classes
GenSeqLike
31. #### def isDefinedAt(idx: Int): Boolean

Tests whether this collection contains given index.

Tests whether this collection contains given index.

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

idx

the index to test

returns

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

Definition Classes
GenSeqLike
32. #### def isEmpty: Boolean

Tests whether the collection is empty.

Tests whether the collection is empty.

returns

`true` if the collection contains no elements, `false` otherwise.

Definition Classes
GenIterableLikeGenTraversableOnce
33. #### final def isInstanceOf[T0]: Boolean

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

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

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

returns

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

Definition Classes
Any
34. #### final def isTraversableAgain: Boolean

Tests whether this collection can be repeatedly traversed.

Tests whether this collection can be repeatedly traversed.

returns

`true`

Definition Classes
GenTraversableLikeGenTraversableOnce
35. #### def lastIndexOf(elem: A, end: Int): Int

[use case]

[use case]
elem

the element value to search for.

end

the end index.

returns

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

Definition Classes
GenSeqLike
36. #### def lastIndexOf(elem: A): Int

[use case]

[use case]
elem

the element value to search for.

returns

the index of the last element of this collection that is equal (wrt `==`) to `elem`, or `-1`, if none exists.

Definition Classes
GenSeqLike
37. #### def lastIndexWhere(p: (A) ⇒ Boolean): Int

Finds index of last element satisfying some predicate.

Finds index of last element satisfying some predicate.

Note: will not terminate for infinite-sized collections.

p

the predicate used to test elements.

returns

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

Definition Classes
GenSeqLike
38. #### abstract def map[B](f: (A) ⇒ B): CC[B]

[use case]

[use case]
B

the element type of the returned collection.

f

the function to apply to each element.

returns

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

Definition Classes
GenTraversableLike
39. #### abstract def max: A

[use case]

[use case]
returns

the largest element of this collection.

Definition Classes
GenTraversableOnce
40. #### abstract def min: A

[use case]

[use case]
returns

the smallest element of this collection

Definition Classes
GenTraversableOnce
41. #### final def ne(arg0: AnyRef): Boolean

Equivalent to `!(this eq that)`.

Equivalent to `!(this eq that)`.

returns

`true` if the argument is not a reference to the receiver object; `false` otherwise.

Definition Classes
AnyRef
42. #### def newBuilder: Builder[A, GenSeq[A]]

The builder that builds instances of type CC[A]

The builder that builds instances of type CC[A]

Attributes
protected[this]
Definition Classes
GenericTraversableTemplateHasNewBuilder
43. #### final def notify(): Unit

Wakes up a single thread that is waiting on the receiver object's monitor.

Wakes up a single thread that is waiting on the receiver object's monitor.

Definition Classes
AnyRef
Note

not specified by SLS as a member of AnyRef

44. #### final def notifyAll(): Unit

Wakes up all threads that are waiting on the receiver object's monitor.

Wakes up all threads that are waiting on the receiver object's monitor.

Definition Classes
AnyRef
Note

not specified by SLS as a member of AnyRef

45. #### abstract def padTo(len: Int, elem: A): CC[A]

[use case]

[use case]
len

the target length

elem

returns

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

Definition Classes
GenSeqLike
46. #### def par: ParSeq[A]

Returns a parallel implementation of this collection.

Returns a parallel implementation of this collection.

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

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

All parallel collections return a reference to themselves.

returns

a parallel implementation of this collection

Definition Classes
Parallelizable
47. #### abstract def patch(from: Int, that: GenSeq[A], replaced: Int): CC[A]

[use case]

[use case]
from

the index of the first replaced element

replaced

the number of elements to drop in the original collection

returns

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

Definition Classes
GenSeqLike
48. #### def prefixLength(p: (A) ⇒ Boolean): Int

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

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

Note: may not terminate for infinite-sized collections.

p

the predicate used to test elements.

returns

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

Definition Classes
GenSeqLike
49. #### abstract def product: A

[use case]

[use case]
returns

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

Definition Classes
GenTraversableOnce
50. #### abstract def reverseMap[B](f: (A) ⇒ B): CC[B]

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

[use case]

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

B

the element type of the returned collection.

f

the function to apply to each element.

returns

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

Definition Classes
GenSeqLike
51. #### abstract def sameElements(that: GenIterable[A]): Boolean

[use case]

[use case]
that

the collection to compare with.

returns

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

Definition Classes
GenIterableLike
52. #### def startsWith[B](that: GenSeq[B]): Boolean

Tests whether this collection starts with the given sequence.

Tests whether this collection starts with the given sequence.

that

the sequence to test

returns

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

Definition Classes
GenSeqLike
53. #### abstract def sum: A

[use case]

[use case]
returns

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

Definition Classes
GenTraversableOnce
54. #### final def synchronized[T0](arg0: ⇒ T0): T0

Definition Classes
AnyRef
55. #### def tail: GenSeq[A]

Selects all elements except the first.

Selects all elements except the first.

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

returns

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

Definition Classes
GenTraversableLike
Exceptions thrown
`UnsupportedOperationException`

if the collection is empty.

56. #### abstract def toArray: Array[A]

[use case]

[use case]
returns

an array containing all elements of this collection. A `ClassManifest` must be available for the element type of this collection.

Definition Classes
GenTraversableOnce
57. #### abstract def toMap[T, U]: Map[T, U]

[use case]

[use case]
returns

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

Definition Classes
GenTraversableOnce
58. #### def toString(): String

Creates a String representation of this object.

Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.

returns

a String representation of the object.

Definition Classes
AnyRef → Any
59. #### def transpose[B](implicit asTraversable: (A) ⇒ GenTraversableOnce[B]): GenSeq[GenSeq[B]]

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

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

B

the type of the elements of each traversable collection.

asTraversable

an implicit conversion which asserts that the element type of this collection is a `Traversable`.

returns

a two-dimensional collection of collections which has as nth row the nth column of this collection.

Definition Classes
GenericTraversableTemplate
Annotations
@migration
Migration

(Changed in version 2.9.0) `transpose` throws an `IllegalArgumentException` if collections are not uniformly sized.

Exceptions thrown
`IllegalArgumentException`

if all collections in this collection are not of the same size.

60. #### def union(that: GenSeq[A]): CC[A]

[use case]

[use case]
that

returns

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

Definition Classes
GenSeqLike
61. #### def unzip[A1, A2](implicit asPair: (A) ⇒ (A1, A2)): (GenSeq[A1], GenSeq[A2])

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

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

asPair

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

returns

a pair collections, containing the first, respectively second half of each element pair of this collection.

Definition Classes
GenericTraversableTemplate
62. #### def unzip3[A1, A2, A3](implicit asTriple: (A) ⇒ (A1, A2, A3)): (GenSeq[A1], GenSeq[A2], GenSeq[A3])

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

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

asTriple

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

returns

a triple collections, containing the first, second, respectively third member of each element triple of this collection.

Definition Classes
GenericTraversableTemplate
63. #### abstract def updated(index: Int, elem: A): CC[A]

[use case]

[use case]
index

the position of the replacement

elem

the replacing element

returns

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

Definition Classes
GenSeqLike
64. #### final def wait(): Unit

Definition Classes
AnyRef
Annotations
()
65. #### final def wait(arg0: Long, arg1: Int): Unit

Definition Classes
AnyRef
Annotations
()
66. #### final def wait(arg0: Long): Unit

Definition Classes
AnyRef
Annotations
()
67. #### abstract def zip[B](that: GenIterable[B]): CC[(A, B)]

[use case]

[use case]
B

the type of the second half of the returned pairs

that

The iterable providing the second half of each result pair

returns

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

Definition Classes
GenIterableLike
68. #### abstract def zipAll[B](that: Iterable[B], thisElem: A, thatElem: B): CC[(A, B)]

[use case]

[use case]
B

the type of the second half of the returned pairs

that

The iterable providing the second half of each result pair

thisElem

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

thatElem

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

returns

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

Definition Classes
GenIterableLike
69. #### abstract def zipWithIndex: CC[(A, Int)]

[use case]

[use case]
returns

A new collection containing pairs consisting of all elements of this collection paired with their index. Indices start at `0`. @example `List("a", "b", "c").zipWithIndex = List(("a", 0), ("b", 1), ("c", 2))`

Definition Classes
GenIterableLike