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Scala 3
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Scala 3/scala/scala.collection/View/Empty

Empty

scala.collection.View.Empty
caseobjectEmpty extendsAbstractView[Nothing]

The empty view

Attributes

Source
View.scala
Graph
Supertypes
Self type
Empty.type

Members list

Value members

Concrete methods

overridedefisEmpty:Boolean

Tests whether the view is empty.

Tests whether the view 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 whenisEmpty is called.

Attributes

Returns

true if the view contains no elements,false otherwise.

Definition Classes
Source
View.scala

Anscala.collection.Iterator over the elements of this view.

Anscala.collection.Iterator over the elements of this view.

If anIterableOnce object is in fact anscala.collection.Iterator, this method always returns itself, in its current state, but if it is anscala.collection.Iterable, this method always returns a newscala.collection.Iterator.

Attributes

Source
View.scala
overridedefknownSize:Int

The number of elements in this view, if it can be cheaply computed, -1 otherwise.

The number of elements in this view, if it can be cheaply computed, -1 otherwise. Cheaply usually means: Not requiring a collection traversal.

Attributes

Definition Classes
Source
View.scala

Inherited methods

finaldef++[B >:Nothing](suffix:IterableOnce[B]):View[B]

Alias forconcat

Alias forconcat

Attributes

Inherited from:
IterableOps
Source
Iterable.scala
finaldefaddString(b:StringBuilder): b.type

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 methodtoString) 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 builderb to which elements were appended.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
finaldefaddString(b:StringBuilder,sep:String): b.type

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 methodtoString) of all elements of this collection, separated by the stringsep.

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 builderb to which elements were appended.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
defaddString(b:StringBuilder,start:String,sep:String,end:String): b.type

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 stringstart and ends with the stringend. Inside, the string representations (w.r.t. the methodtoString) of all elements of this collection are separated by the stringsep.

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 builderb 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.

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 functionpf 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.

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, orNone if none exists.

Example

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

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
defconcat[B >:Nothing](suffix:IterableOnce[B]):View[B]

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

Returns a new iterable collection containing the elements from the left hand operand followed by the elements from the right hand operand. The element type of the iterable collection 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 iterable collection which contains all elements of this iterable collection followed by all elements ofsuffix.

Inherited from:
IterableOps
Source
Iterable.scala
defcopyToArray[B >:Nothing](xs:Array[B],start:Int,len:Int):Int

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

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

Fills the given arrayxs starting at indexstart with at mostlen 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, orlen 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
defcopyToArray[B >:Nothing](xs:Array[B],start:Int):Int

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

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

Fills the given arrayxs starting at indexstart 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
defcopyToArray[B >:Nothing](xs:Array[B]):Int

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

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

Fills the given arrayxs starting at indexstart 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.

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 ofthat

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 andp(x, y) istrue for all corresponding elementsx of this iterator andy ofthat, otherwisefalse

Inherited from:
IterableOnceOps
Source
IterableOnce.scala

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

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 predicatep.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala

Selects all elements except the firstn ones.

Selects all elements except the firstn 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 firstn ones, or else the empty iterable collection, if this iterable collection has less thann elements. Ifn is negative, don't drop any elements.

Inherited from:
IterableOps
Source
Iterable.scala

Selects all elements except lastn ones.

Selects all elements except lastn 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 lastn ones, or else the empty iterable collection, if this iterable collection has less thann elements. Ifn is negative, don't drop any elements.

Inherited from:
IterableOps
Source
Iterable.scala

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

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

The matching prefix starts with the first element of this iterable 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 iterable 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)

Usespan to obtain both the prefix and suffix. UsefilterNot to drop all elements that satisfy the 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 predicatep.

Inherited from:
IterableOps
Source
Iterable.scala
overridedefempty:View[Nothing]

The empty iterable of the same type as this iterable

The empty iterable of the same type as this iterable

Attributes

Returns

an empty iterable of typeC.

Definition Classes
Inherited from:
View
Source
View.scala

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

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 predicatep is satisfied by at least one element of this collection, otherwisefalse

Inherited from:
IterableOnceOps
Source
IterableOnce.scala

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

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 predicatep. 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.

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 predicatepred. Their order may not be preserved.

Inherited from:
IterableOps
Source
Iterable.scala

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.

Value parameters

p

the predicate used to test elements.

Attributes

Returns

an option value containing the first element in the collection that satisfiesp, orNone 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.

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 Setdef lettersOf(words: Seq[String]) = words flatMap (word => word.toSet)// lettersOf will return a Set[Char], not a Seqdef 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 functionf to each element of this iterable collection and concatenating the results.

Inherited from:
IterableOps
Source
Iterable.scala
defflatten[B](implicitasIterable:Nothing=>IterableOnce[B]):View[B]

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

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 anIterable.

Attributes

Returns

a new iterable collection resulting from concatenating all element iterable collections.

Inherited from:
IterableOps
Source
Iterable.scala
deffold[A1 >:Nothing](z:A1)(op: (A1,A1)=>A1):A1

Applies the given binary operatorop to the given initial valuez and all elements of this collection.

Applies the given binary operatorop to the given initial valuez 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 forList concatenation or1 for multiplication.

The default implementation inIterableOnce is equivalent tofoldLeft but may be overridden for more efficient traversal orders.

Note: will not terminate for infinite-sized collections.

Type parameters

A1

The type parameter for the binary operator, a supertype ofA.

Value parameters

op

A binary operator; must be associative for the result to always be the same across runs.

z

An initial value; may be used an arbitrary number of times in the computation of the result; must be a neutral value forop for the result to always be the same across runs.

Attributes

Returns

The result of applyingop between all the elements andz, orz if this collection is empty.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
deffoldLeft[B](z:B)(op: (B,Nothing)=>B):B

Applies the given binary operatorop to the given initial valuez and all elements of this collection, going left to right.

Applies the given binary operatorop to the given initial valuez 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 ifx1,x2, ...,xn are the elements of this collection, the result isop( 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.

Type parameters

B

The result type of the binary operator.

Value parameters

op

A binary operator.

z

An initial value.

Attributes

Returns

The result of applyingop toz and all elements of this collection, going left to right. Returnsz if this collection is empty.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
deffoldRight[B](z:B)(op: (Nothing,B)=>B):B

Applies the given binary operatorop to all elements of this collection and the given initial valuez, going right to left.

Applies the given binary operatorop to all elements of this collection and the given initial valuez, 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 ifx1,x2, ...,xn are the elements of this collection, the result isop(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.

Type parameters

B

The result type of the binary operator.

Value parameters

op

A binary operator.

z

An initial value.

Attributes

Returns

The result of applyingop to all elements of this collection andz, going right to left. Returnsz if this collection is empty.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala

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

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 predicatep holds for all elements of this collection, otherwisefalse.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
defforeach[U](f:Nothing=>U):Unit

Appliesf to each element for its side effects.

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

Attributes

Inherited from:
IterableOnceOps
Source
IterableOnce.scala

Defines how to turn a givenIterable[A] into a collection of typeC.

Defines how to turn a givenIterable[A] into a collection of typeC.

This process can be done in a strict way or a non-strict way (ie. without evaluating the elements of the resulting collections). In other words, this methods defines the evaluation model of the collection.

Attributes

Note

When implementing a custom collection type and refiningC to the new type, this method needs to be overridden (the compiler will issue an error otherwise). In the common case whereC =:= CC[A], this can be done by mixing in thescala.collection.IterableFactoryDefaults trait, which implements the method usingiterableFactory.

As witnessed by the@uncheckedVariance annotation, using this method might be unsound. However, as long as it is called with anIterable[A] obtained fromthis collection (as it is the case in the implementations of operations where we use aView[A]), it is safe.

Inherited from:
IterableFactoryDefaults
Source
Iterable.scala
defgroupBy[K](f:Nothing=>K):Map[K,View[Nothing]]

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

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 keyk is bound to a iterable collection of those elementsx for whichf(x) equalsk.

Inherited from:
IterableOps
Source
Iterable.scala
defgroupMap[K,B](key:Nothing=>K)(f:Nothing=>B):Map[K,View[B]]

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

Partitions this iterable collection into a map of iterable collections according to a discriminator functionkey. Each element in a group is transformed into a value of typeB using thevalue function.

It is equivalent togroupBy(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
defgroupMapReduce[K,B](key:Nothing=>K)(f:Nothing=>B)(reduce: (B,B)=>B):Map[K,B]

Partitions this iterable collection into a map according to a discriminator functionkey.

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

It is equivalent togroupBy(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.

Partitions elements in fixed size iterable collections.

Value parameters

size

the number of elements per group

Attributes

Returns

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

See also
Inherited from:
IterableOps
Source
Iterable.scala

Selects the first element of this iterable collection.

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

NoSuchElementExceptionif the iterable collection is empty.

Inherited from:
IterableOps
Source
Iterable.scala

Optionally selects the first element.

Optionally selects the first element.

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

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.

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 ofinit.

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
Inherited from:
IterableOps
Source
Iterable.scala

The companion object of this view, providing various factory methods.

The companion object of this view, providing various factory methods.

Attributes

Note

When implementing a custom collection type and refiningCC 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).

Definition Classes
Inherited from:
View
Source
View.scala

Selects the last element.

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

NoSuchElementExceptionIf the iterable collection is empty.

Inherited from:
IterableOps
Source
Iterable.scala

Optionally selects the last element.

Optionally selects the last element.

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

Attributes

Returns

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

Inherited from:
IterableOps
Source
Iterable.scala
deflazyZip[B](that:Iterable[B]):LazyZip2[Nothing,B,this.type]

Analogous tozip except that the elements in each collection are not consumed until a strict operation is invoked on the returnedLazyZip2 decorator.

Analogous tozip except that the elements in each collection are not consumed until a strict operation is invoked on the returnedLazyZip2 decorator.

Calls tolazyZip can be chained to support higher arities (up to 4) without incurring the expense of constructing and deconstructing intermediary tuples.

val xs = List(1, 2, 3)val res = (xs lazyZip xs lazyZip xs lazyZip xs).map((a, b, c, d) => a + b + c + d)// res == List(4, 8, 12)

Type parameters

B

the type of the second element in each eventual pair

Value parameters

that

the iterable providing the second element of each eventual pair

Attributes

Returns

a decoratorLazyZip2 that allows strict operations to be performed on the lazily evaluated pairs or chained calls tolazyZip. Implicit conversion toIterable[(A, B)] is also supported.

Inherited from:
Iterable
Source
Iterable.scala
defmap[B](f:Nothing=>B):View[B]

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

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 functionf to each element of this iterable collection and collecting the results.

Inherited from:
IterableOps
Source
Iterable.scala
defmax[B >:Nothing](implicitord:Ordering[B]):Nothing

Finds the largest element.

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 orderingord.

Throws

UnsupportedOperationExceptionif this collection is empty.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
defmaxBy[B](f:Nothing=>B)(implicitord:Ordering[B]):Nothing

Finds the first element which yields the largest value measured by functionf.

Finds the first element which yields the largest value measured by functionf.

Note: will not terminate for infinite-sized collections.

Type parameters

B

The result type of the functionf.

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 functionf with respect to the orderingcmp.

Throws

UnsupportedOperationExceptionif this collection is empty.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
defmaxByOption[B](f:Nothing=>B)(implicitord:Ordering[B]):Option[Nothing]

Finds the first element which yields the largest value measured by functionf.

Finds the first element which yields the largest value measured by functionf.

Note: will not terminate for infinite-sized collections.

Type parameters

B

The result type of the functionf.

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 functionf with respect to the orderingcmp.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
defmaxOption[B >:Nothing](implicitord:Ordering[B]):Option[Nothing]

Finds the largest element.

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 orderingord.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
defmin[B >:Nothing](implicitord:Ordering[B]):Nothing

Finds the smallest element.

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 orderingord.

Throws

UnsupportedOperationExceptionif this collection is empty.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
defminBy[B](f:Nothing=>B)(implicitord:Ordering[B]):Nothing

Finds the first element which yields the smallest value measured by functionf.

Finds the first element which yields the smallest value measured by functionf.

Note: will not terminate for infinite-sized collections.

Type parameters

B

The result type of the functionf.

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 functionf with respect to the orderingcmp.

Throws

UnsupportedOperationExceptionif this collection is empty.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
defminByOption[B](f:Nothing=>B)(implicitord:Ordering[B]):Option[Nothing]

Finds the first element which yields the smallest value measured by functionf.

Finds the first element which yields the smallest value measured by functionf.

Note: will not terminate for infinite-sized collections.

Type parameters

B

The result type of the functionf.

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 functionf with respect to the orderingcmp.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
defminOption[B >:Nothing](implicitord:Ordering[B]):Option[Nothing]

Finds the smallest element.

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 orderingord.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala

Displays all elements of this collection in a string.

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 methodtoString) of all elements of this collection follow each other without any separator string.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
finaldefmkString(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.

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 methodtoString) of all elements of this collection are separated by the stringsep.

Example

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

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
finaldefmkString(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.

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 stringstart and ends with the stringend. Inside, the string representations (w.r.t. the methodtoString) of all elements of this collection are separated by the stringsep.

Example

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

Inherited from:
IterableOnceOps
Source
IterableOnce.scala

Attributes

Returns

a strict builder for the same collection type. Note that in the case of lazy collections (e.g.scala.collection.View orscala.collection.immutable.LazyList), it is possible to implement this method but the resultingBuilder will break laziness. As a consequence, operations should preferably be implemented withfromSpecific instead of this method.

Note

When implementing a custom collection type and refiningC to the new type, this method needs to be overridden (the compiler will issue an error otherwise). In the common case whereC =:= CC[A], this can be done by mixing in thescala.collection.IterableFactoryDefaults trait, which implements the method usingiterableFactory.

As witnessed by the@uncheckedVariance annotation, using this method might be unsound. However, as long as the returned builder is only fed withA values taken fromthis instance, it is safe.

Inherited from:
IterableFactoryDefaults
Source
Iterable.scala

Tests whether the collection is not empty.

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 predicatep and, second, all elements that do not.

A pair of, first, all elements that satisfy predicatep 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 ofpartition inStrictOptimizedIterableOps, which requires only a single traversal.

Attributes

Inherited from:
IterableOps
Source
Iterable.scala
defpartitionMap[A1,A2](f:Nothing=>Either[A1,A2]): (View[A1],View[A2])

Applies a functionf to each element of the iterable collection and returns a pair of iterable collections: the first one made of those values returned byf that were wrapped inscala.util.Left, and the second one made of those wrapped inscala.util.Right.

Applies a functionf to each element of the iterable collection and returns a pair of iterable collections: the first one made of those values returned byf that were wrapped inscala.util.Left, and the second one made of those wrapped inscala.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 anscala.util.Either

Attributes

Returns

a pair of iterable collections: the first one made of those values returned byf that were wrapped inscala.util.Left, and the second one made of those wrapped inscala.util.Right.

Inherited from:
IterableOps
Source
Iterable.scala
defproduct[B >:Nothing](implicitnum:Numeric[B]):B

Multiplies together the elements of this collection.

Multiplies together the elements of this collection.

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

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 innum.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala

An iterator over the names of all the elements of this product.

An iterator over the names of all the elements of this product.

Attributes

Inherited from:
Product
Source
Product.scala

An iterator over all the elements of this product.

An iterator over all the elements of this product.

Attributes

Returns

in the default implementation, anIterator[Any]

Inherited from:
Product
Source
Product.scala
defreduce[B >:Nothing](op: (B,B)=>B):B

Applies the given binary operatorop to all elements of this collection.

Applies the given binary operatorop 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.

Type parameters

B

The type parameter for the binary operator, a supertype ofA.

Value parameters

op

A binary operator; must be associative for the result to always be the same across runs.

Attributes

Returns

The result of applyingop between all the elements if the collection is nonempty.

Throws

UnsupportedOperationExceptionif this collection is empty.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
defreduceLeft[B >:Nothing](op: (B,Nothing)=>B):B

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

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

"Going left to right" only makes sense if this collection is ordered: then ifx1,x2, ...,xn are the elements of this collection, the result isop( 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.

Type parameters

B

The result type of the binary operator, a supertype ofA.

Value parameters

op

A binary operator.

Attributes

Returns

The result of applyingop to all elements of this collection, going left to right.

Throws

UnsupportedOperationExceptionif this collection is empty.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
defreduceLeftOption[B >:Nothing](op: (B,Nothing)=>B):Option[B]

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

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

The behavior is the same asreduceLeft except that the value isNone 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.

Type parameters

B

The result type of the binary operator, a supertype ofA.

Value parameters

op

A binary operator.

Attributes

Returns

The result of reducing this collection withop going left to right if the collection is nonempty, inside aSome, andNone otherwise.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
defreduceOption[B >:Nothing](op: (B,B)=>B):Option[B]

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

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

The behavior is the same asreduce except that the value isNone 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.

Type parameters

B

A type parameter for the binary operator, a supertype ofA.

Value parameters

op

A binary operator; must be associative for the result to always be the same across runs.

Attributes

Returns

The result of reducing this collection withop if the collection is nonempty, inside aSome, andNone otherwise.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
defreduceRight[B >:Nothing](op: (Nothing,B)=>B):B

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

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

"Going right to left" only makes sense if this collection is ordered: then ifx1,x2, ...,xn are the elements of this collection, the result isop(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.

Type parameters

B

The result type of the binary operator, a supertype ofA.

Value parameters

op

A binary operator.

Attributes

Returns

The result of applyingop to all elements of this collection, going right to left.

Throws

UnsupportedOperationExceptionif this collection is empty.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
defreduceRightOption[B >:Nothing](op: (Nothing,B)=>B):Option[B]

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

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

The behavior is the same asreduceRight except that the value isNone 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.

Type parameters

B

The result type of the binary operator, a supertype ofA.

Value parameters

op

A binary operator.

Attributes

Returns

The result of reducing this collection withop going right to left if the collection is nonempty, inside aSome, andNone otherwise.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala

Attributes

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
defscan[B >:Nothing](z:B)(op: (B,B)=>B):View[B]

Computes a prefix scan of the elements of the collection.

Computes a prefix scan of the elements of the collection.

Note: The neutral elementz 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 operatorop

Attributes

Returns

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

Inherited from:
IterableOps
Source
Iterable.scala
defscanLeft[B](z:B)(op: (B,Nothing)=>B):View[B]

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

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
defscanRight[B](z:B)(op: (Nothing,B)=>B):View[B]

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

The size of this collection.

The size of this collection.

Note: will not terminate for infinite-sized collections.

Attributes

Returns

the number of elements in this collection.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala

Compares the size of this iterable collection to the size of anotherIterable.

Compares the size of this iterable collection to the size of anotherIterable.

Value parameters

that

theIterable whose size is compared with this iterable collection's size.

Attributes

Returns

A valuex where

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

The method as implemented here does not callsize directly; its running time isO(this.size min that.size) instead ofO(this.size + that.size). The method should be overridden if computingsize is cheap andknownSize returns-1.

Inherited from:
IterableOps
Source
Iterable.scala
defsizeCompare(otherSize:Int):Int

Compares the size of this iterable collection to a test value.

Compares the size of this iterable collection to a test value.

Value parameters

otherSize

the test value that gets compared with the size.

Attributes

Returns

A valuex where

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

The method as implemented here does not callsize directly; its running time isO(size min otherSize) instead ofO(size). The method should be overridden if computingsize is cheap andknownSize returns-1.

See also
Inherited from:
IterableOps
Source
Iterable.scala

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

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

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

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

Attributes

Inherited from:
IterableOps
Source
Iterable.scala
defslice(from:Int,until:Int):View[Nothing]

Selects an interval of elements.

Selects an interval of elements. The returned iterable collection is made up of all elementsx 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 indexfrom extending up to (but not including) indexuntil 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.)

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 sizesize, except the last element (which may be the only element) will be smaller if there are fewer thansize elements remaining to be grouped.

See also
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 ingrouped.)

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

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 sizesize, except for a non-empty collection with less thansize elements, which returns an iterator that produces the source collection itself as its only element.

See also
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.

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 predicatep 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 satisfyp, and the rest of this iterable collection.

Inherited from:
IterableOps
Source
Iterable.scala
overridedefsplitAt(n:Int): (View[Nothing],View[Nothing])

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

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 firstn elements of this iterable collection, and the other elements.

Definition Classes
Inherited from:
IterableOps
Source
Iterable.scala
defstepper[S <:Stepper[_]](implicitshape:StepperShape[Nothing,S]):S

Returns ascala.collection.Stepper for the elements of this collection.

Returns ascala.collection.Stepper for the elements of this collection.

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

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

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

Attributes

Inherited from:
IterableOnce
Source
IterableOnce.scala
defsum[B >:Nothing](implicitnum:Numeric[B]):B

Sums the elements of this collection.

Sums the elements of this collection.

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

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 innum.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala

The rest of the collection without its first element.

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 oftail.

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 firstn elements.

Selects the firstn 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 firstn elements of this iterable collection, or else the whole iterable collection, if it has less thann elements. Ifn is negative, returns an empty iterable collection.

Inherited from:
IterableOps
Source
Iterable.scala

Selects the lastn elements.

Selects the lastn 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 lastn elements of this iterable collection, or else the whole iterable collection, if it has less thann elements. Ifn is negative, returns an empty iterable collection.

Inherited from:
IterableOps
Source
Iterable.scala

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.

Value parameters

p

The predicate used to test elements.

Attributes

Returns

the longest prefix of this iterable collection whose elements all satisfy the predicatep.

Inherited from:
IterableOps
Source
Iterable.scala
overridedeftapEach[U](f:Nothing=>U):View[Nothing]

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 applyf to their elements immediately, while lazy collections like Views and LazyLists will only applyf 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
Inherited from:
IterableOps
Source
Iterable.scala
defto[C1](factory:Factory[Nothing,C1]):C1

Given a collection factoryfactory, converts this collection to the appropriate representation for the current element typeA.

Given a collection factoryfactory, converts this collection to the appropriate representation for the current element typeA. Example uses:

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

Attributes

Inherited from:
IterableOnceOps
Source
IterableOnce.scala

Converts this collection to anArray.

Converts this collection to anArray.

Implementation note: DO NOT callArray.from from this method.

Type parameters

B

The type of elements of the result, a supertype ofA.

Attributes

Returns

This collection as anArray[B].

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
finaldeftoBuffer[B >:Nothing]:Buffer[B]

Converts this collection to aBuffer.

Converts this collection to aBuffer.

Type parameters

B

The type of elements of the result, a supertype ofA.

Attributes

Returns

This collection as aBuffer[B].

Inherited from:
IterableOnceOps
Source
IterableOnce.scala

Converts this collection to anIndexedSeq.

Converts this collection to anIndexedSeq.

Attributes

Returns

This collection as anIndexedSeq[A].

Inherited from:
IterableOnceOps
Source
IterableOnce.scala

Converts this collection to aList.

Converts this collection to aList.

Attributes

Returns

This collection as aList[A].

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
deftoMap[K,V](implicitev:Nothing<:< (K,V)):Map[K,V]

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

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

Type parameters

K

The key type for the resulting map.

V

The value type for the resulting map.

Value parameters

ev

An implicit coercion fromA to[K, V].

Attributes

Returns

This collection as aMap[K, V].

Inherited from:
IterableOnceOps
Source
IterableOnce.scala

Attributes

Returns

This collection as aSeq[A]. This is equivalent toto(Seq) but might be faster.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
deftoSet[B >:Nothing]:Set[B]

Converts this collection to aSet.

Converts this collection to aSet.

Type parameters

B

The type of elements of the result, a supertype ofA.

Attributes

Returns

This collection as aSet[B].

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
overridedeftoString:String

Converts this view to a string.

Converts this view to a string.

Attributes

Returns

a string representation of this collection. By default this string consists of theclassName of this view, followed by all elements separated by commas and enclosed in parentheses.

Definition Classes
Inherited from:
View
Source
View.scala

Converts this collection to aVector.

Converts this collection to aVector.

Attributes

Returns

This collection as aVector[A].

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
deftranspose[B](implicitasIterable:Nothing=>Iterable[B]):View[View[B]]

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

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 anIterable.

Attributes

Returns

a two-dimensional iterable collection of iterable collections which has asnth row thenth column of this iterable collection.

Throws

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

Inherited from:
IterableOps
Source
Iterable.scala
defunzip[A1,A2](implicitasPair:Nothing=> (A1,A2)): (View[A1],View[A2])

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

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
defunzip3[A1,A2,A3](implicitasTriple:Nothing=> (A1,A2,A3)): (View[A1],View[A2],View[A3])

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

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
overridedefview:View[Nothing]

A view over the elements of this collection.

A view over the elements of this collection.

Attributes

Definition Classes
Inherited from:
View
Source
View.scala

Creates a non-strict filter of this iterable collection.

Creates a non-strict filter of this iterable collection.

Note: the difference betweenc filter p andc withFilter p is that the former creates a new collection, whereas the latter only restricts the domain of subsequentmap,flatMap,foreach, andwithFilter 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 classWithFilter, which supportsmap,flatMap,foreach, andwithFilter operations. All these operations apply to those elements of this iterable collection which satisfy the predicatep.

Inherited from:
IterableOps
Source
Iterable.scala
defzip[B](that:IterableOnce[B]):View[(Nothing,B)]

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 andthat. The length of the returned collection is the minimum of the lengths of this iterable collection andthat.

Inherited from:
IterableOps
Source
Iterable.scala
defzipAll[A1 >:Nothing,B](that:Iterable[B],thisElem:A1,thatElem:B):View[(A1,B)]

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 ifthat is shorter than this iterable collection.

thisElem

the element to be used to fill up the result if this iterable collection is shorter thanthat.

Attributes

Returns

a new collection of the type of this iterable collection containing pairs consisting of corresponding elements of this iterable collection andthat. The length of the returned collection is the maximum of the lengths of this iterable collection andthat. If this iterable collection is shorter thanthat,thisElem values are used to pad the result. Ifthat 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.

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 at0.

Example

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

Inherited from:
IterableOps
Source
Iterable.scala

Deprecated and Inherited methods

def++:[B >:Nothing](that:IterableOnce[B]):View[B]

Attributes

Deprecated
[Since version 2.13.0]Use ++ instead of ++: for collections of type Iterable
Inherited from:
IterableOps
Source
Iterable.scala
finaldef/:[B](z:B)(op: (B,Nothing)=>B):B

Attributes

Deprecated
[Since version 2.13.0]Use foldLeft instead of /:
Inherited from:
IterableOnceOps
Source
IterableOnce.scala
finaldef:\[B](z:B)(op: (Nothing,B)=>B):B

Attributes

Deprecated
[Since version 2.13.0]Use foldRight instead of :\\
Inherited from:
IterableOnceOps
Source
IterableOnce.scala
defaggregate[B](z:=>B)(seqop: (B,Nothing)=>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.

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

Forparallel collections, use theaggregate method specified byscala.collection.parallel.ParIterableLike.

Type parameters

B

the result type, produced byseqop,combop, and by this function as a final result.

Value parameters

combop

an associative operator for combining sequential results, unused for sequential collections.

seqop

the binary operator used to accumulate the result.

z

the start value, a neutral element forseqop.

Attributes

Deprecated
[Since version 2.13.0]For sequential collections, prefer `foldLeft(z)(seqop)`. For parallel collections, use `ParIterableLike#aggregate`.
Inherited from:
IterableOnceOps
Source
IterableOnce.scala

Attributes

Deprecated
[Since version 2.13.0]Use iterableFactory instead
Inherited from:
IterableOps
Source
Iterable.scala
finaldefcopyToBuffer[B >:Nothing](dest:Buffer[B]):Unit

Attributes

Deprecated
[Since version 2.13.0]Use `dest ++= coll` instead
Inherited from:
IterableOnceOps
Source
IterableOnce.scala

Attributes

Deprecated
[Since version 2.13.0]Views no longer know about their underlying collection type; .force always returns an IndexedSeq
Inherited from:
View
Source
View.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 asStream, the predicate returnstrue if all elements have been computed. It returnsfalse if the stream is not yet evaluated to the end. Non-empty Iterators usually returnfalse 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 thathasDefiniteSize returnstrue. However, checkinghasDefiniteSize 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

methodknownSize for a more useful alternative

Deprecated
[Since version 2.13.0]Check .knownSize instead of .hasDefiniteSize for more actionable information (see scaladoc for details)

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 thoughhasDefiniteSize returnsfalse.

Inherited from:
IterableOnceOps
Source
IterableOnce.scala
finaldefrepr:View[Nothing]

Attributes

Deprecated
[Since version 2.13.0]Use coll instead of repr in a collection implementation, use the collection value itself from the outside
Inherited from:
IterableOps
Source
Iterable.scala
defseq:this.type

Attributes

Deprecated
[Since version 2.13.0]Iterable.seq always returns the iterable itself
Inherited from:
Iterable
Source
Iterable.scala
finaldeftoIterable:this.type

Attributes

Returns

This collection as anIterable[A]. No new collection will be built ifthis is already anIterable[A].

Deprecated
[Since version 2.13.7]toIterable is internal and will be made protected; its name is similar to `toList` or `toSeq`, but it doesn\'t copy non-immutable collections
Inherited from:
Iterable
Source
Iterable.scala

Attributes

Deprecated
[Since version 2.13.0]Use .iterator instead of .toIterator
Inherited from:
IterableOnceOps
Source
IterableOnce.scala

Attributes

Deprecated
[Since version 2.13.0]Use .to(LazyList) instead of .toStream
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
[Since version 2.13.0]toTraversable is internal and will be made protected; its name is similar to `toList` or `toSeq`, but it doesn\'t copy non-immutable collections
Inherited from:
IterableOps
Source
Iterable.scala
defview(from:Int,until:Int):View[Nothing]

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

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

Attributes

Deprecated
[Since version 2.13.0]Use .view.slice(from, until) instead of .view(from, until)
Inherited from:
IterableOps
Source
Iterable.scala
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