# AbstractMap

Explicit instantiation of the `Map`

trait to reduce class file size in subclasses.

- Source:
- Map.scala

## Value members

### Inherited methods

Alias for `concat`

Alias for `concat`

- Inherited from:
- IterableOps
- Source:
- Iterable.scala

Appends all elements of this collection to a string builder.

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

) of all elements of this collection without any separator string.

Example:

```
scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)
scala> val b = new StringBuilder()
b: StringBuilder =
scala> val h = a.addString(b)
h: StringBuilder = 1234
```

- Value parameters:
- b
the string builder to which elements are appended.

- Returns:
the string builder

`b`

to which elements were appended.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

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

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

)
of all elements of this collection, separated by the string `sep`

.

Example:

```
scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)
scala> val b = new StringBuilder()
b: StringBuilder =
scala> a.addString(b, ", ")
res0: StringBuilder = 1, 2, 3, 4
```

- Value parameters:
- b
the string builder to which elements are appended.

- sep
the separator string.

- Returns:
the string builder

`b`

to which elements were appended.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

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

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 parameters:
- C
the result type of the transformation function.

- Value parameters:
- 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:
- PartialFunction
- Source:
- PartialFunction.scala

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

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 parameters:
- C
the result type of the transformation function.

- Value parameters:
- 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
- Inherited from:
- PartialFunction
- Source:
- PartialFunction.scala

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`

.

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

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

- Type parameters:
- K2
the key type of the returned map.

- V2
the value type of the returned map.

- Value parameters:
- 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:
- MapOps
- Source:
- Map.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

- Returns:
an option value containing pf applied to the first value for which it is defined, or

`None`

if none exists.- Example:
`Seq("a", 1, 5L).collectFirst({ case x: Int => x*10 }) = Some(10)`

- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

Composes another partial function `k`

with this partial function so that this
partial function gets applied to results of `k`

.

Composes another partial function `k`

with this partial function so that this
partial function gets applied to results of `k`

.

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 parameters:
- R
the parameter type of the transformation function.

- Value parameters:
- 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:
- PartialFunction
- Source:
- PartialFunction.scala

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

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

- Type parameters:
- A
the type to which function

`g`

can be applied

- Value parameters:
- 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 parameters:
- B
the element type of the returned collection.

- Value parameters:
- 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:
- IterableOps
- Source:
- Iterable.scala

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.

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 array `xs`

starting at index `start`

with at most `len`

elements of this collection.

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

elements have been copied.

- Type parameters:
- B
the type of the elements of the array.

- Value parameters:
- len
the maximal number of elements to copy.

- start
the starting index of xs.

- xs
the array to fill.

- Returns:
the number of elements written to the array

- Note:
Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.

- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

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

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

Fills the given array `xs`

starting at index `start`

with values of this collection.

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

- Type parameters:
- B
the type of the elements of the array.

- Value parameters:
- start
the starting index of xs.

- xs
the array to fill.

- Returns:
the number of elements written to the array

- Note:
Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.

- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

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

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

Fills the given array `xs`

starting at index `start`

with values of this collection.

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

- Type parameters:
- B
the type of the elements of the array.

- Value parameters:
- xs
the array to fill.

- 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 of

`that`

- Value parameters:
- 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:
- 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.

- Returns:
the number of elements satisfying the predicate

`p`

.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

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.

Selects all elements except last n ones.

Selects all elements except last n ones.

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

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

- Returns:
a iterable collection consisting of all elements of this iterable collection except the last

`n`

ones, or else the empty iterable collection, if this iterable collection has less than`n`

elements. If`n`

is negative, don't drop any elements.- Inherited from:
- IterableOps
- Source:
- Iterable.scala

Returns an extractor object with a `unapplySeq`

method, which extracts each element of a sequence data.

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:
- PartialFunction
- Source:
- PartialFunction.scala

Equality of maps is implemented using the lookup method get.

Equality of maps is implemented using the lookup method get. This method returns `true`

if

the argument

`o`

is a`Map`

,the two maps have the same size, and

for every

`(key, value)`

pair in this map,`other.get(key) == Some(value)`

.

The implementation of `equals`

checks the canEqual method, so subclasses of `Map`

can narrow down the equality
to specific map types. The `Map`

implementations in the standard library can all be compared, their `canEqual`

methods return `true`

.

Note: The `equals`

method only respects the equality laws (symmetry, transitivity) if the two maps use the same
key equivalence function in their lookup operation. For example, the key equivalence operation in a
scala.collection.immutable.TreeMap is defined by its ordering. Comparing a `TreeMap`

with a `HashMap`

leads
to unexpected results if `ordering.equiv(k1, k2)`

(used for lookup in `TreeMap`

) is different from `k1 == k2`

(used for lookup in `HashMap`

).

```
scala> import scala.collection.immutable._
scala> val ord: Ordering[String] = _ compareToIgnoreCase _
scala> TreeMap("A" -> 1)(ord) == HashMap("a" -> 1)
val res0: Boolean = false
scala> HashMap("a" -> 1) == TreeMap("A" -> 1)(ord)
val res1: Boolean = true
```

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.

- Returns:
`true`

if the given predicate`p`

is satisfied by at least one element of this collection, otherwise`false`

- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

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.

- Returns:
an option value containing the first element in the collection that satisfies

`p`

, or`None`

if none exists.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

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

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

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

Folds the elements of this collection using the specified associative binary operator.
The default implementation in `IterableOnce`

is equivalent to `foldLeft`

but may be
overridden for more efficient traversal orders.

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

Note: will not terminate for infinite-sized collections.

- Type parameters:
- A1
a type parameter for the binary operator, a supertype of

`A`

.

- Value parameters:
- op
a binary operator that must be associative.

- z
a neutral element for the fold operation; may be added to the result an arbitrary number of times, and must not change the result (e.g.,

`Nil`

for list concatenation, 0 for addition, or 1 for multiplication).

- Returns:
the result of applying the fold operator

`op`

between all the elements and`z`

, or`z`

if this collection is empty.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

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

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

Note: will not terminate for infinite-sized collections.

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

- Type parameters:
- B
the result type of the binary operator.

- Value parameters:
- op
the binary operator.

- z
the start value.

- Returns:
the result of inserting

`op`

between consecutive elements of this collection, going left to right with the start value`z`

on the left:`op(...op(z, x1), x2, ..., xn)`

where`x1, ..., xn`

are the elements of this collection. Returns`z`

if this collection is empty.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

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

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

Note: will not terminate for infinite-sized collections.

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

- Type parameters:
- B
the result type of the binary operator.

- Value parameters:
- op
the binary operator.

- z
the start value.

- Returns:
the result of inserting

`op`

between consecutive elements of this collection, going right to left with the start value`z`

on the right:`op(x1, op(x2, ... op(xn, z)...))`

where`x1, ..., xn`

are the elements of this collection. Returns`z`

if this collection is empty.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

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

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.

- Returns:
`true`

if this collection is empty or the given predicate`p`

holds for all elements of this collection, otherwise`false`

.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

Apply `f`

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

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

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

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

- Type parameters:
- V1
the result type of the default computation.

- Value parameters:
- 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:
- MapOps
- Source:
- Map.scala

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.

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

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

That is, every key

`k`

is bound to a iterable collection of those elements`x`

for which`f(x)`

equals`k`

.- Inherited from:
- IterableOps
- Source:
- Iterable.scala

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

.

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

.
Each element in a group is transformed into a value of type `B`

using the `value`

function.

It is equivalent to `groupBy(key).mapValues(_.map(f))`

, but more efficient.

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

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

- Type parameters:
- B
the type of values returned by the transformation function

- K
the type of keys returned by the discriminator function

- Value parameters:
- f
the element transformation function

- key
the discriminator function

- Inherited from:
- IterableOps
- Source:
- Iterable.scala

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

.

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

. All the values that
have the same discriminator are then transformed by the `f`

function and then reduced into a
single value with the `reduce`

function.

It is equivalent to `groupBy(key).mapValues(_.map(f).reduce(reduce))`

, but more efficient.

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

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

- 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

- Returns:
An iterator producing iterable collections of size

`size`

, except the last will be less than size`size`

if the elements don't divide evenly.- See also:
scala.collection.Iterator, method

`grouped`

- Inherited from:
- IterableOps
- Source:
- Iterable.scala

Selects the first element of this iterable collection.

Selects the first element of this iterable collection.

- Returns:
the first element of this iterable collection.

- Throws:
- NoSuchElementException
if the iterable collection is empty.

- Inherited from:
- IterableOps
- Source:
- Iterable.scala

Optionally selects the first element.

Optionally selects the first element.

- 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.

- 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 the collection is empty.

Tests whether the collection is empty.

Note: Implementations in subclasses that are not repeatedly traversable must take
care not to consume any elements when `isEmpty`

is called.

- Returns:
`true`

if the collection contains no elements,`false`

otherwise.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

Iterator can be used only once

Iterator can be used only once

- Inherited from:
- IterableOnce
- Source:
- IterableOnce.scala

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

- Inherited from:
- IterableOnce
- Source:
- IterableOnce.scala

Selects the last element.

Selects the last element.

- Returns:
The last element of this iterable collection.

- Throws:
- NoSuchElementException
If the iterable collection is empty.

- Inherited from:
- IterableOps
- Source:
- Iterable.scala

Optionally selects the last element.

Optionally selects the last element.

- 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.

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 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

- 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:
- Iterable.scala

Turns this partial function into a plain function returning an `Option`

result.

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

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.

- Returns:
the largest element of this collection with respect to the ordering

`ord`

.- Throws:
- UnsupportedOperationException
if this collection is empty.

- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

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

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

Note: will not terminate for infinite-sized collections.

- Type parameters:
- B
The result type of the function f.

- Value parameters:
- cmp
An ordering to be used for comparing elements.

- f
The measuring function.

- Returns:
the first element of this collection with the largest value measured by function f with respect to the ordering

`cmp`

.- Throws:
- UnsupportedOperationException
if this collection is empty.

- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

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

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

Note: will not terminate for infinite-sized collections.

- Type parameters:
- B
The result type of the function f.

- Value parameters:
- cmp
An ordering to be used for comparing elements.

- f
The measuring function.

- Returns:
an option value containing the first element of this collection with the largest value measured by function f with respect to the ordering

`cmp`

.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

Finds the largest element.

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.

- Returns:
an option value containing the largest element of this collection with respect to the ordering

`ord`

.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

Finds the smallest element.

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.

- Returns:
the smallest element of this collection with respect to the ordering

`ord`

.- Throws:
- UnsupportedOperationException
if this collection is empty.

- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

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

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

Note: will not terminate for infinite-sized collections.

- Type parameters:
- B
The result type of the function f.

- Value parameters:
- cmp
An ordering to be used for comparing elements.

- f
The measuring function.

- Returns:
the first element of this collection with the smallest value measured by function f with respect to the ordering

`cmp`

.- Throws:
- UnsupportedOperationException
if this collection is empty.

- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

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

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

Note: will not terminate for infinite-sized collections.

- Type parameters:
- B
The result type of the function f.

- Value parameters:
- cmp
An ordering to be used for comparing elements.

- f
The measuring function.

- Returns:
an option value containing the first element of this collection with the smallest value measured by function f with respect to the ordering

`cmp`

.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

Finds the smallest element.

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.

- Returns:
an option value containing the smallest element of this collection with respect to the ordering

`ord`

.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

Displays all elements of this collection in a string.

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.

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.

- Returns:
a string representation of this collection. In the resulting string the string representations (w.r.t. the method

`toString`

) of all elements of this collection are separated by the string`sep`

.- Example:
`List(1, 2, 3).mkString("|") = "1|2|3"`

- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

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

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.

- Returns:
a string representation of this collection. The resulting string begins with the string

`start`

and ends with the string`end`

. Inside, the string representations (w.r.t. the method`toString`

) of all elements of this collection are separated by the string`sep`

.- Example:
`List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"`

- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

Tests whether the collection is not empty.

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.

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

- Type parameters:
- A1
the argument type of the fallback function

- B1
the result type of the fallback function

- Value parameters:
- 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:
- PartialFunction
- Source:
- PartialFunction.scala

A pair of, first, all elements that satisfy predicate `p`

and, second,
all elements that do not.

A pair of, first, all elements that satisfy predicate `p`

and, second,
all elements that do not. Interesting because it splits a collection in two.

The default implementation provided here needs to traverse the collection twice.
Strict collections have an overridden version of `partition`

in `StrictOptimizedIterableOps`

,
which requires only a single traversal.

- Inherited from:
- IterableOps
- Source:
- Iterable.scala

Applies a function `f`

to each element of the iterable collection and returns a pair of iterable collections: the first one
made of those values returned by `f`

that were wrapped in scala.util.Left, and the second
one made of those wrapped in scala.util.Right.

Applies a function `f`

to each element of the iterable collection and returns a pair of iterable collections: the first one
made of those values returned by `f`

that were wrapped in scala.util.Left, and the second
one made of those wrapped in scala.util.Right.

Example:

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

- Type parameters:
- A1
the element type of the first resulting collection

- A2
the element type of the second resulting collection

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

- Returns:
a pair of iterable collections: the first one made of those values returned by

`f`

that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.- Inherited from:
- IterableOps
- Source:
- Iterable.scala

Multiplies up the elements of this collection.

Multiplies up the elements of this collection.

Note: will not terminate for infinite-sized collections.

- Type parameters:
- B
the result type of the

`*`

operator.

- Value parameters:
- num
an implicit parameter defining a set of numeric operations which includes the

`*`

operator to be used in forming the product.

- Returns:
the product of all elements of this collection with respect to the

`*`

operator in`num`

.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

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

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

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

- Type parameters:
- B
A type parameter for the binary operator, a supertype of

`A`

.

- Value parameters:
- op
A binary operator that must be associative.

- Returns:
The result of applying reduce operator

`op`

between all the elements if the collection is nonempty.- Throws:
- UnsupportedOperationException
if this collection is empty.

- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

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

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

Note: will not terminate for infinite-sized collections.

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

- Type parameters:
- B
the result type of the binary operator.

- Value parameters:
- op
the binary operator.

- Returns:
the result of inserting

`op`

between consecutive elements of this collection, going left to right:`op( op( ... op(x1, x2) ..., xn-1), xn)`

where`x1, ..., xn`

are the elements of this collection.- Throws:
- UnsupportedOperationException
if this collection is empty.

- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

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

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

Note: will not terminate for infinite-sized collections.

- Type parameters:
- B
the result type of the binary operator.

- Value parameters:
- op
the binary operator.

- Returns:
an option value containing the result of

`reduceLeft(op)`

if this collection is nonempty,`None`

otherwise.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

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

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

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

- Type parameters:
- B
A type parameter for the binary operator, a supertype of

`A`

.

- Value parameters:
- op
A binary operator that must be associative.

- Returns:
An option value containing result of applying reduce operator

`op`

between all the elements if the collection is nonempty, and`None`

otherwise.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

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

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

Note: will not terminate for infinite-sized collections.

- Type parameters:
- B
the result type of the binary operator.

- Value parameters:
- 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.

- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

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

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

Note: will not terminate for infinite-sized collections.

- Type parameters:
- B
the result type of the binary operator.

- Value parameters:
- op
the binary operator.

- Returns:
an option value containing the result of

`reduceRight(op)`

if this collection is nonempty,`None`

otherwise.- 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 parameters:
- 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`

.- Inherited from:
- PartialFunction
- Source:
- PartialFunction.scala

Computes a prefix scan of the elements of the collection.

Computes a prefix scan of the elements of the collection.

Note: The neutral element `z`

may be applied more than once.

- Type parameters:
- B
element type of the resulting collection

- Value parameters:
- op
the associative operator for the scan

- z
neutral element for the operator

`op`

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

- 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: 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

- 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.

- 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`

.

Compares the size of this iterable collection to the size of another `Iterable`

.

- Value parameters:
- 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`

.- Inherited from:
- IterableOps
- Source:
- Iterable.scala

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.

- 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:
- 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 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

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

- Returns:
An iterator producing iterable collections of size

`size`

, except the last element (which may be the only element) will be smaller if there are fewer than`size`

elements remaining to be grouped.- See also:
scala.collection.Iterator, method

`sliding`

- Example:
`List(1, 2, 3, 4, 5).sliding(2, 2) = Iterator(List(1, 2), List(3, 4), List(5))`

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

- Inherited from:
- IterableOps
- Source:
- Iterable.scala

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

.)

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

.)

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

- Value parameters:
- size
the number of elements per group

- Returns:
An iterator producing iterable collections of size

`size`

, except for a non-empty collection with less than`size`

elements, which returns an iterator that produces the source collection itself as its only element.- See also:
scala.collection.Iterator, method

`sliding`

- Example:
`List().sliding(2) = empty iterator`

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

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

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

- Inherited from:
- IterableOps
- Source:
- Iterable.scala

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

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 returnedFor collections of

`Double`

or`Float`

, a scala.collection.DoubleStepper is returnedFor collections of

`Long`

a scala.collection.LongStepper is returnedFor 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.

Sums up the elements of this collection.

Note: will not terminate for infinite-sized collections.

- Type parameters:
- B
the result type of the

`+`

operator.

- Value parameters:
- num
an implicit parameter defining a set of numeric operations which includes the

`+`

operator to be used in forming the sum.

- Returns:
the sum of all elements of this collection with respect to the

`+`

operator in`num`

.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

The rest of the collection without its first element.

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

Selects the last n elements.

Selects the last n elements.

- Value parameters:
- 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.- Inherited from:
- IterableOps
- Source:
- Iterable.scala

Takes longest prefix of elements that satisfy a predicate.

Takes longest prefix of elements that satisfy a predicate.

- Value parameters:
- p
The predicate used to test elements.

- Returns:
the longest prefix of this iterable collection whose elements all satisfy the predicate

`p`

.- Inherited from:
- IterableOps
- Source:
- Iterable.scala

Given a collection factory `factory`

, convert this collection to the appropriate
representation for the current element type `A`

.

Given a collection factory `factory`

, convert this collection to the appropriate
representation for the current element type `A`

. Example uses:

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

- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

Convert collection to array.

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

- Returns:
This collection as a

`Seq[A]`

. This is equivalent to`to(Seq)`

but might be faster.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

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 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.

- Inherited from:
- IterableOps
- Source:
- Iterable.scala

Tries to extract a `B`

from an `A`

in a pattern matching expression.

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.

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.

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

- Inherited from:
- IterableOps
- Source:
- Iterable.scala

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

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.

- 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

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

- Returns:
a new iterable collection containing pairs consisting of corresponding elements of this iterable collection and

`that`

. The length of the returned collection is the minimum of the lengths of this iterable collection and`that`

.- Inherited from:
- IterableOps
- Source:
- Iterable.scala

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

Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs. If one of the two collections is shorter than the other, placeholder elements are used to extend the shorter collection to the length of the longer.

- Value parameters:
- that
the iterable providing the second half of each result pair

- thatElem
the element to be used to fill up the result if

`that`

is shorter than this iterable collection.- thisElem
the element to be used to fill up the result if this iterable collection is shorter than

`that`

.

- Returns:
a new collection of type

`That`

containing pairs consisting of corresponding elements of this iterable collection and`that`

. The length of the returned collection is the maximum of the lengths of this iterable collection and`that`

. If this iterable collection is shorter than`that`

,`thisElem`

values are used to pad the result. If`that`

is shorter than this iterable collection,`thatElem`

values are used to pad the result.- Inherited from:
- IterableOps
- Source:
- Iterable.scala

### Deprecated and Inherited methods

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

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

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

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

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

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

Filters this map by retaining only keys satisfying a predicate.

Filters this map by retaining only keys satisfying a predicate.

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

Tests whether this collection is known to have a finite size.
All strict collections are known to have finite size. For a non-strict
collection such as `Stream`

, the predicate returns `true`

if all
elements have been computed. It returns `false`

if the stream is
not yet evaluated to the end. Non-empty Iterators usually return
`false`

even if they were created from a collection with a known
finite size.

Note: many collection methods will not work on collections of infinite sizes.
The typical failure mode is an infinite loop. These methods always attempt a
traversal without checking first that `hasDefiniteSize`

returns `true`

.
However, checking `hasDefiniteSize`

can provide an assurance that size is
well-defined and non-termination is not a concern.

- Returns:
`true`

if this collection is known to have finite size,`false`

otherwise.- See also:
method

`knownSize`

for a more useful alternative- Deprecated
This method is deprecated in 2.13 because it does not provide any actionable information. As noted above, even the collection library itself does not use it. When there is no guarantee that a collection is finite, it is generally best to attempt a computation anyway and document that it will not terminate for infinite collections rather than backing out because this would prevent performing the computation on collections that are in fact finite even though

`hasDefiniteSize`

returns`false`

.- Inherited from:
- IterableOnceOps
- Source:
- IterableOnce.scala

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

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

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

- Deprecated
- Inherited from:
- Iterable
- Source:
- Iterable.scala

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

- Deprecated
- 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.

- Returns:
An Iterable containing all elements of this iterable collection.

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

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

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

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