TapEach

Source

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

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

Example:

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

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

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

Value Params

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

Returns

the string builder b to which elements were appended.

Inherited from

Source

Definition Classes: MapOps -> IterableOnceOps
Inherited from: MapOps
Source: Map.scala

Composes this partial function with another partial function that gets applied to results of this partial function.

Note that calling isDefinedAt on the resulting partial function may apply the first partial function and execute its side effect. It is highly recommended to call applyOrElse instead of isDefinedAt / apply for efficiency.

Type Params

C: the result type of the transformation function.

Value Params

k: the transformation function

Returns

a partial function with the domain of this partial function narrowed by other partial function, which maps arguments x to k(this(x)).

Inherited from

Source

Composes this partial function with a transformation function that gets applied to results of this partial function.

If the runtime type of the function is a PartialFunction then the other andThen method is used (note its cautions).

Type Params

C: the result type of the transformation function.

Value Params

k: the transformation function

Returns

a partial function with the domain of this partial function, possibly narrowed by the specified function, which maps arguments x to k(this(x)).

Definition Classes

PartialFunction -> Function1

Inherited from

Source

@throws(scala.throws.$lessinit$greater$default$1[scala.NoSuchElementException])

Retrieves the value which is associated with the given key.

Retrieves the value which is associated with the given key. This method invokes the default method of the map if there is no mapping from the given key to a value. Unless overridden, the default method throws a NoSuchElementException.

Value Params

key: the key

Returns

the value associated with the given key, or the result of the map's default method, if none exists.

Inherited from

Source

Definition Classes: MapOps -> PartialFunction
Inherited from: MapOps
Source: Map.scala

Inherited from: IterableOps
Source: Iterable.scala

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

Type Params

K2: the key type of the returned map.
V2: the value type of the returned map.

Value Params

pf: the partial function which filters and maps the map.

Returns

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

Inherited from

Source

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 Params

pf: the partial function

Returns

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

Example

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

Inherited from

Source

Composes another partial function k with this partial function so that this partial function gets applied to results of k.

Type Params

R: the parameter type of the transformation function.

Value Params

k: the transformation function

Returns

a partial function with the domain of other partial function narrowed by this partial function, which maps arguments x to this(k(x)).

Inherited from

Source

@unspecialized

Composes two instances of Function1 in a new Function1, with this function applied last.

Type Params

A: the type to which function g can be applied

Value Params

g: a function A => T1

Returns

a new function f such that f(x) == apply(g(x))

Inherited from

Function1

Source

Function1.scala

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 Params

B: the element type of the returned collection.

Value Params

suffix: the traversable to append.

Returns

a new iterable collection which contains all elements of this iterable collection followed by all elements of suffix.

Inherited from

Source

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

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

Value Params

suffix: the traversable to append.

Returns

a new map which contains all elements of this map followed by all elements of suffix.

Inherited from

Source

Tests whether this map contains a binding for a key.

Value Params

key: the key

Returns

true if there is a binding for key in this map, false otherwise.

Inherited from

Source

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

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

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

Type Params

B: the type of the elements of the array.

Value Params

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

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

Source

@deprecatedOverriding("This should always forward to the 3-arg version of this method", since = "2.13.4")

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

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

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

Type Params

B: the type of the elements of the array.

Value Params

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

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

Source

@deprecatedOverriding("This should always forward to the 3-arg version of this method", since = "2.13.4")

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

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

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

Type Params

B: the type of the elements of the array.

Value Params

xs: the array to fill.

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

Source

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 Params

B: the type of the elements of that

Value Params

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

Returns

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

Inherited from

Source

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

Note: will not terminate for infinite-sized collections.

Value Params

p: the predicate used to test elements.

Returns

the number of elements satisfying the predicate p.

Inherited from

Source

@throws(scala.throws.$lessinit$greater$default$1[scala.NoSuchElementException])

Defines the default value computation for the map, returned when a key is not found The method implemented here throws an exception, but it might be overridden in subclasses.

Value Params

key: the given key value for which a binding is missing.

Inherited from

Source

Inherited from: IterableOps
Source: Iterable.scala

Selects all elements except last n ones.

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

Value Params

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

Returns

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

Inherited from

Source

Inherited from: IterableOps
Source: Iterable.scala

Returns an extractor object with a unapplySeq method, which extracts each element of a sequence data.

Example

val firstChar: String => Option[Char] = _.headOption
Seq("foo", "bar", "baz") match {
  case firstChar.unlift.elementWise(c0, c1, c2) =>
    println(s"$c0, $c1, $c2") // Output: f, b, b
}

Inherited from

Source

Definition Classes: MapView -> View -> IterableFactoryDefaults -> IterableOps
Inherited from: MapView
Source: MapView.scala

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

Note: may not terminate for infinite-sized collections.

Value Params

p: the predicate used to test elements.

Returns

true if the given predicate p is satisfied by at least one element of this collection, otherwise false

Inherited from

Source

Definition Classes: MapView -> IterableOps -> IterableOnceOps
Inherited from: MapView
Source: MapView.scala

Filters this map by retaining only keys satisfying a predicate.

Value Params

p: the predicate used to test keys

Returns

an immutable map consisting only of those key value pairs of this map where the key satisfies the predicate p. The resulting map wraps the original map without copying any elements.

Definition Classes

MapView -> MapOps

Inherited from

MapView

Source

MapView.scala

Definition Classes: MapView -> IterableOps -> IterableOnceOps
Inherited from: MapView
Source: MapView.scala

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

Note: may not terminate for infinite-sized collections.

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

Value Params

p: the predicate used to test elements.

Returns

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

Inherited from

Source

Inherited from: IterableOps
Source: Iterable.scala

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

Value Params

f: the function to apply to each element.

Returns

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

Inherited from

Source

Inherited from: IterableOps
Source: Iterable.scala

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

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

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

Note: will not terminate for infinite-sized collections.

Type Params

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

Value Params

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

Returns

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

Inherited from

Source

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

Note: will not terminate for infinite-sized collections.

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

Type Params

B: the result type of the binary operator.

Value Params

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

Returns

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

Inherited from

Source

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

Note: will not terminate for infinite-sized collections.

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

Type Params

B: the result type of the binary operator.

Value Params

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

Returns

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

Inherited from

Source

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

Note: may not terminate for infinite-sized collections.

Value Params

p: the predicate used to test elements.

Returns

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

Inherited from

Source

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

Inherited from: IterableOnceOps
Source: IterableOnce.scala

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

Inherited from: MapOps
Source: Map.scala

Inherited from: IterableFactoryDefaults
Source: Iterable.scala

Returns the value associated with a key, or a default value if the key is not contained in the map.

Type Params

V1: the result type of the default computation.

Value Params

default: a computation that yields a default value in case no binding for key is found in the map.
key: the key.

Returns

the value associated with key if it exists, otherwise the result of the default computation.

Inherited from

Source

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 Params

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

Value Params

f: the discriminator function.

Returns

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

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

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

Inherited from

Source

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

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

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

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

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

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

Type Params

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

Value Params

f: the element transformation function
key: the discriminator function

Inherited from

Source

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

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

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

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

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

Inherited from: IterableOps
Source: Iterable.scala

Partitions elements in fixed size iterable collections.

Value Params

size: the number of elements per group

Returns

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

See also

scala.collection.Iterator, method grouped

Inherited from

Source

Selects the first element of this iterable collection.

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

Returns

the first element of this iterable collection.

Throws

NoSuchElementException: if the iterable collection is empty.

Inherited from

Source

Optionally selects the first element.

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

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

The initial part of the collection without its last element.

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

Inherited from: IterableOps
Source: Iterable.scala

Iterates over the inits of this iterable collection.

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

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

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 map contains a binding for a key.

Tests whether this map contains a binding for a key. This method, which implements an abstract method of trait PartialFunction, is equivalent to contains.

Value Params

key: the key

Returns

true if there is a binding for key in this map, false otherwise.

Inherited from

Source

Definition Classes: IterableOps -> IterableOnceOps
Inherited from: IterableOps
Source: Iterable.scala

Definition Classes: View -> Iterable -> IterableOps
Inherited from: View
Source: View.scala

Collects all keys of this map in a set.

Returns: a set containing all keys of this map.
Inherited from: MapOps
Source: Map.scala

Returns a Stepper for the keys of this map.

Returns a Stepper for the keys of this map. See method stepper.

Inherited from: MapOps
Source: Map.scala

Creates a view over all keys of this map.

Returns: the keys of this map as a view.
Definition Classes: MapView -> MapOps
Inherited from: MapView
Source: MapView.scala

Creates an iterator for all keys.

Returns: an iterator over all keys.
Inherited from: MapOps
Source: Map.scala

Selects the last element.

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

Returns

The last element of this iterable collection.

Throws

NoSuchElementException: If the iterable collection is empty.

Inherited from

Source

Optionally selects the last element.

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

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

Analogous to zip except that the elements in each collection are not consumed until a strict operation is invoked on the returned LazyZip2 decorator.

Calls to lazyZip 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 Params

B: the type of the second element in each eventual pair

Value Params

that: the iterable providing the second element of each eventual pair

Returns

a decorator LazyZip2 that allows strict operations to be performed on the lazily evaluated pairs or chained calls to lazyZip. Implicit conversion to Iterable[(A, B)] is also supported.

Inherited from

Iterable

Source

Turns this partial function into a plain function returning an Option result.

Returns: a function that takes an argument x to Some(this(x)) if this is defined for x, and to None otherwise.
See also: Function.unlift
Inherited from: PartialFunction
Source: PartialFunction.scala

Inherited from: IterableOps
Source: Iterable.scala

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

Value Params

f: the function to apply to each element.

Returns

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

Inherited from

Source

Inherited from: MapView
Source: MapView.scala

Transforms this map by applying a function to every retrieved value.

Value Params

f: the function used to transform values of this map.

Returns

a map view which maps every key of this map to f(this(key)). The resulting map wraps the original map without copying any elements.

Definition Classes

MapView -> MapOps

Inherited from

MapView

Source

MapView.scala

Finds the largest element.

Note: will not terminate for infinite-sized collections.

Type Params

B: The type over which the ordering is defined.

Value Params

ord: An ordering to be used for comparing elements.

Returns

the largest element of this collection with respect to the ordering ord.

Throws

UnsupportedOperationException: if this collection is empty.

Inherited from

Source

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

Note: will not terminate for infinite-sized collections.

Type Params

B: The result type of the function f.

Value Params

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

Returns

the first element of this collection with the largest value measured by function f with respect to the ordering cmp.

Throws

UnsupportedOperationException: if this collection is empty.

Inherited from

Source

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

Note: will not terminate for infinite-sized collections.

Type Params

B: The result type of the function f.

Value Params

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

Returns

an option value containing the first element of this collection with the largest value measured by function f with respect to the ordering cmp.

Inherited from

Source

Finds the largest element.

Note: will not terminate for infinite-sized collections.

Type Params

B: The type over which the ordering is defined.

Value Params

ord: An ordering to be used for comparing elements.

Returns

an option value containing the largest element of this collection with respect to the ordering ord.

Inherited from

Source

Finds the smallest element.

Note: will not terminate for infinite-sized collections.

Type Params

B: The type over which the ordering is defined.

Value Params

ord: An ordering to be used for comparing elements.

Returns

the smallest element of this collection with respect to the ordering ord.

Throws

UnsupportedOperationException: if this collection is empty.

Inherited from

Source

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

Note: will not terminate for infinite-sized collections.

Type Params

B: The result type of the function f.

Value Params

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

Returns

the first element of this collection with the smallest value measured by function f with respect to the ordering cmp.

Throws

UnsupportedOperationException: if this collection is empty.

Inherited from

Source

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

Note: will not terminate for infinite-sized collections.

Type Params

B: The result type of the function f.

Value Params

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

Returns

an option value containing the first element of this collection with the smallest value measured by function f with respect to the ordering cmp.

Inherited from

Source

Finds the smallest element.

Note: will not terminate for infinite-sized collections.

Type Params

B: The type over which the ordering is defined.

Value Params

ord: An ordering to be used for comparing elements.

Returns

an option value containing the smallest element of this collection with respect to the ordering ord.

Inherited from

Source

Displays all elements of this collection in a string.

Delegates to addString, which can be overridden.

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

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

Delegates to addString, which can be overridden.

Value Params

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.

Example

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

Inherited from

Source

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

Delegates to addString, which can be overridden.

Value Params

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

Example

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

Inherited from

Source

Inherited from: IterableFactoryDefaults
Source: Iterable.scala

@deprecatedOverriding("nonEmpty is defined as !isEmpty; override isEmpty instead", "2.13.0")

Tests whether the collection is not empty.

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

Composes this partial function with a fallback partial function which gets applied where this partial function is not defined.

Type Params

A1: the argument type of the fallback function
B1: the result type of the fallback function

Value Params

that: the fallback function

Returns

a partial function which has as domain the union of the domains of this partial function and that. The resulting partial function takes x to this(x) where this is defined, and to that(x) where it is not.

Inherited from

Source

Definition Classes: MapView -> IterableOps
Inherited from: MapView
Source: MapView.scala

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

Example:

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

Type Params

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

Value Params

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

Returns

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

Inherited from

Source

Multiplies up the elements of this collection.

Note: will not terminate for infinite-sized collections.

Type Params

B: the result type of the * operator.

Value Params

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

Returns

the product of all elements of this collection with respect to the * operator in num.

Inherited from

Source

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

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

Type Params

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

Value Params

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.

Throws

UnsupportedOperationException: if this collection is empty.

Inherited from

Source

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

Note: will not terminate for infinite-sized collections.

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

Type Params

B: the result type of the binary operator.

Value Params

op: the binary operator.

Returns

the result of inserting op between consecutive elements of this collection, going left to right: op( op( ... op(x1, x2) ..., xn-1), xn) where x1, ..., xn are the elements of this collection.

Throws

UnsupportedOperationException: if this collection is empty.

Inherited from

Source

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

Note: will not terminate for infinite-sized collections.

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

Type Params

B: the result type of the binary operator.

Value Params

op: the binary operator.

Returns

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

Inherited from

Source

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

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

Type Params

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

Value Params

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.

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

Note: will not terminate for infinite-sized collections.

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

Type Params

B: the result type of the binary operator.

Value Params

op: the binary operator.

Returns

the result of inserting op between consecutive elements of this collection, going right to left: op(x1, op(x2, ..., op(xn-1, xn)...)) where x1, ..., xn are the elements of this collection.

Throws

UnsupportedOperationException: if this collection is empty.

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

Note: will not terminate for infinite-sized collections.

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

Type Params

B: the result type of the binary operator.

Value Params

op: the binary operator.

Returns

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

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Inherited from: IterableOnceOps
Source: IterableOnce.scala

Composes this partial function with an action function which gets applied to results of this partial function.

Composes this partial function with an action function which gets applied to results of this partial function. The action function is invoked only for its side effects; its result is ignored.

Note that expression pf.runWith(action)(x) is equivalent to

if(pf isDefinedAt x) { action(pf(x)); true } else false

except that runWith is implemented via applyOrElse and thus potentially more efficient. Using runWith avoids double evaluation of pattern matchers and guards for partial function literals.

Value Params

action: the action function

Returns

a function which maps arguments x to isDefinedAt(x). The resulting function runs action(this(x)) where this is defined.

See also

applyOrElse.

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Computes a prefix scan of the elements of the collection.

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

Type Params

B: element type of the resulting collection

Value Params

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

Returns

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

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Inherited from: IterableOps
Source: Iterable.scala

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

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

Note: will not terminate for infinite-sized collections.

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

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

Example:

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

Type Params

B: the type of the elements in the resulting collection

Value Params

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

Returns

collection with intermediate results

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The size of this collection.

Note: will not terminate for infinite-sized collections.

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 another Iterable.

Value Params

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

Returns

A value x where

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

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

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

Value Params

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

Returns

A value x where

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

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

See also

sizeIs

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

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

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

Inherited from: IterableOps
Source: Iterable.scala

Inherited from: IterableOps
Source: Iterable.scala

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

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

Value Params

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

Returns

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

See also

scala.collection.Iterator, method sliding

Example

List(1, 2, 3, 4, 5).sliding(2, 2) = Iterator(List(1, 2), List(3, 4), List(5))

List(1, 2, 3, 4, 5, 6).sliding(2, 3) = Iterator(List(1, 2), List(4, 5))

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

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

Value Params

size: the number of elements per group

Returns

An iterator producing iterable collections of size size, except for a non-empty collection with less than size elements, which returns an iterator that produces the source collection itself as its only element.

See also

scala.collection.Iterator, method sliding

Example

List().sliding(2) = empty iterator

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

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

List(1, 2, 3).sliding(2) = Iterator(List(1, 2), List(2, 3))

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Inherited from: IterableOps
Source: Iterable.scala

Definition Classes: IterableOps -> IterableOnceOps
Inherited from: IterableOps
Source: Iterable.scala

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

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

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

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

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

Inherited from: IterableOnce
Source: IterableOnce.scala

Sums up the elements of this collection.

Note: will not terminate for infinite-sized collections.

Type Params

B: the result type of the + operator.

Value Params

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

Returns

the sum of all elements of this collection with respect to the + operator in num.

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The rest of the collection without its first element.

Inherited from: IterableOps
Source: Iterable.scala

Iterates over the tails of this iterable collection.

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

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

Inherited from: IterableOps
Source: Iterable.scala

Selects the last n elements.

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

Value Params

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

Returns

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

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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 Params

p: The predicate used to test elements.

Returns

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

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Definition Classes: MapView -> IterableOps -> IterableOnceOps
Inherited from: MapView
Source: MapView.scala

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

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

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

Inherited from: IterableOnceOps
Source: IterableOnce.scala

Convert collection to array.

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

Inherited from: IterableOnceOps
Source: IterableOnce.scala

Inherited from: IterableOnceOps
Source: IterableOnce.scala

Inherited from: IterableOnceOps
Source: IterableOnce.scala

Inherited from: Iterable
Source: Iterable.scala

Inherited from: IterableOnceOps
Source: IterableOnce.scala

Inherited from: IterableOnceOps
Source: IterableOnce.scala

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

Inherited from: IterableOnceOps
Source: IterableOnce.scala

Definition Classes: MapView -> View -> Iterable -> Function1 -> Any
Inherited from: MapView
Source: MapView.scala

Inherited from: IterableOnceOps
Source: IterableOnce.scala

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

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

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

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

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

Type Params

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

Value Params

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

Returns

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

Throws

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

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Source

Tries to extract a B from an A in a pattern matching expression.

Inherited from: PartialFunction
Source: PartialFunction.scala

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

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

Type Params

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

Value Params

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

Returns

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

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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 Params

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 Params

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

Returns

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

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Returns a Stepper for the values of this map.

Returns a Stepper for the values of this map. See method stepper.

Inherited from: MapOps
Source: Map.scala

Creates a view over all values of this map.

Returns: the values of this map as a view.
Definition Classes: MapView -> MapOps
Inherited from: MapView
Source: MapView.scala

Creates an iterator for all values in this map.

Returns: an iterator over all values that are associated with some key in this map.
Inherited from: MapOps
Source: Map.scala

Definition Classes: MapView -> View -> MapOps -> IterableOps
Inherited from: MapView
Source: MapView.scala

Definition Classes: MapView -> IterableOps
Inherited from: MapView
Source: MapView.scala

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

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

Type Params

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

Value Params

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

Returns

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

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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 Params

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

Returns

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

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