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# Map 

### Companion object Map

#### trait Map[K, +V] extends Iterable[(K, V)] with collection.Map[K, V] with MapLike[K, V, Map[K, V]]

A generic trait for immutable maps. Concrete classes have to provide functionality for the abstract methods in `Map`:

```def get(key: K): Option[V]
def iterator: Iterator[(K, V)]
def + [V1 >: V](kv: (K, V1)): Map[K, V1]
def -(key: K): Map[K, V]```
Self Type
Map[K, V]
Source
Map.scala
Since

1

Linear Supertypes
MapLike[K, V, Map[K, V]], collection.Map[K, V], collection.MapLike[K, V, Map[K, V]], Subtractable[K, Map[K, V]], PartialFunction[K, V], (K) ⇒ V, GenMap[K, V], GenMapLike[K, V, Map[K, V]], Iterable[(K, V)], collection.Iterable[(K, V)], IterableLike[(K, V), Map[K, V]], Equals, GenIterable[(K, V)], GenIterableLike[(K, V), Map[K, V]], Traversable[(K, V)], Immutable, collection.Traversable[(K, V)], GenTraversable[(K, V)], GenericTraversableTemplate[(K, V), Iterable], TraversableLike[(K, V), Map[K, V]], GenTraversableLike[(K, V), Map[K, V]], Parallelizable[(K, V), ParMap[K, V]], TraversableOnce[(K, V)], GenTraversableOnce[(K, V)], FilterMonadic[(K, V), Map[K, V]], HasNewBuilder[(K, V), Map[K, V]], AnyRef, Any
Known Subclasses
Ordering
1. Alphabetic
2. By Inheritance
Inherited
1. Map
2. MapLike
3. Map
4. MapLike
5. Subtractable
6. PartialFunction
7. Function1
8. GenMap
9. GenMapLike
10. Iterable
11. Iterable
12. IterableLike
13. Equals
14. GenIterable
15. GenIterableLike
16. Traversable
17. Immutable
18. Traversable
19. GenTraversable
20. GenericTraversableTemplate
21. TraversableLike
22. GenTraversableLike
23. Parallelizable
24. TraversableOnce
25. GenTraversableOnce
27. HasNewBuilder
28. AnyRef
29. Any
Implicitly
1. by CollectionsHaveToParArray
4. by StringFormat
5. by Ensuring
6. by ArrowAssoc
7. by alternateImplicit
1. Hide All
2. Show All
Visibility
1. Public
2. All

### Type Members

1. class DefaultKeySet extends AbstractSet[K] with Set[K] with Serializable

The implementation class of the set returned by `keySet`.

The implementation class of the set returned by `keySet`.

Attributes
protected
Definition Classes
MapLike
Annotations
()
2. class DefaultValuesIterable extends AbstractIterable[V] with Iterable[V] with Serializable

The implementation class of the iterable returned by `values`.

The implementation class of the iterable returned by `values`.

Attributes
protected
Definition Classes
MapLike
3. class FilteredKeys extends AbstractMap[K, V] with DefaultMap[K, V]
Attributes
protected
Definition Classes
MapLike
4. class MappedValues[W] extends AbstractMap[K, W] with DefaultMap[K, W]
Attributes
protected
Definition Classes
MapLike
5. class WithFilter extends FilterMonadic[A, Repr]

A class supporting filtered operations.

A class supporting filtered operations. Instances of this class are returned by method `withFilter`.

Definition Classes
TraversableLike
6. type Self = Map[K, V]

The type implementing this traversable

The type implementing this traversable

Attributes
protected[this]
Definition Classes
TraversableLike
7. class ImmutableDefaultKeySet extends DefaultKeySet with Set[K]
Attributes
protected
Definition Classes
MapLike

### Abstract Value Members

1. abstract def +[V1 >: V](kv: (K, V1)): Map[K, V1]

Add a key/value pair to this map, returning a new map.

Add a key/value pair to this map, returning a new map.

V1

the type of the value in the key/value pair.

kv

the key/value pair.

returns

A new map with the new binding added to this map.

Definition Classes
MapMapLikeMapLikeGenMapLike
2. abstract def get(key: K): Option[V]

Optionally returns the value associated with a key.

Optionally returns the value associated with a key.

key

the key value

returns

an option value containing the value associated with `key` in this map, or `None` if none exists.

Definition Classes
MapLikeGenMapLike
3. abstract def iterator: Iterator[(K, V)]

Creates a new iterator over all key/value pairs of this map

Creates a new iterator over all key/value pairs of this map

returns

the new iterator

Definition Classes
MapLikeIterableLikeGenIterableLike

### Concrete Value Members

1. final def !=(arg0: Any)

Test two objects for inequality.

Test two objects for inequality.

returns

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

Definition Classes
AnyRef → Any
2. final def ##(): Int

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

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

returns

a hash value consistent with ==

Definition Classes
AnyRef → Any
3. def +[V1 >: V](elem1: (K, V1), elem2: (K, V1), elems: (K, V1)*): Map[K, V1]

Adds two or more elements to this collection and returns a new collection.

Adds two or more elements to this collection and returns a new collection.

V1

the type of the added values

elem1

elem2

elems

returns

A new map with the new bindings added to this map.

Definition Classes
MapLikeMapLike
4. def ++[V1 >: V](xs: GenTraversableOnce[(K, V1)]): Map[K, V1]

Adds a number of elements provided by a traversable object and returns a new collection with the added elements.

Adds a number of elements provided by a traversable object and returns a new collection with the added elements.

V1

the type of the added values

xs

the traversable object consisting of key-value pairs.

returns

a new immutable map with the bindings of this map and those from `xs`.

Definition Classes
MapLikeMapLike
5. def ++[B >: (K, V), That](that: GenTraversableOnce[B])(implicit bf: CanBuildFrom[Map[K, V], B, That]): That

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

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

B

the element type of the returned collection.

That

the class of the returned collection. Where possible, `That` is the same class as the current collection class `Repr`, but this depends on the element type `B` being admissible for that class, which means that an implicit instance of type `CanBuildFrom[Repr, B, That]` is found.

that

the traversable to append.

bf

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

returns

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

Definition Classes
TraversableLikeGenTraversableLike
6. def ++:[B >: (K, V), That](that: collection.Traversable[B])(implicit bf: CanBuildFrom[Map[K, V], B, That]): That

As with `++`, returns a new collection containing the elements from the left operand followed by the elements from the right operand.

As with `++`, returns a new collection containing the elements from the left operand followed by the elements from the right operand.

It differs from `++` in that the right operand determines the type of the resulting collection rather than the left one. Mnemonic: the COLon is on the side of the new COLlection type.

Example:

```scala> val x = List(1)
x: List[Int] = List(1)

scala> val z = x ++: y

This overload exists because: for the implementation of `++:` we should reuse that of `++` because many collections override it with more efficient versions.

Since `TraversableOnce` has no `++` method, we have to implement that directly, but `Traversable` and down can use the overload.

B

the element type of the returned collection.

That

the class of the returned collection. Where possible, `That` is the same class as the current collection class `Repr`, but this depends on the element type `B` being admissible for that class, which means that an implicit instance of type `CanBuildFrom[Repr, B, That]` is found.

that

the traversable to append.

bf

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

returns

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

Definition Classes
TraversableLike
7. def ++:[B](that: TraversableOnce[B]): Map[B]

[use case] As with `++`, returns a new collection containing the elements from the left operand followed by the elements from the right operand.

[use case]

As with `++`, returns a new collection containing the elements from the left operand followed by the elements from the right operand.

It differs from `++` in that the right operand determines the type of the resulting collection rather than the left one. Mnemonic: the COLon is on the side of the new COLlection type.

Example:

```scala> val x = List(1)
x: List[Int] = List(1)

scala> val z = x ++: y
B

the element type of the returned collection.

that

the traversable to append.

returns

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

Definition Classes
TraversableLike
Full Signature

#### def ++:[B >: (K, V), That](that: TraversableOnce[B])(implicit bf: CanBuildFrom[Map[K, V], B, That]): That

8. def -(elem1: K, elem2: K, elems: K*): Map[K, V]

Creates a new collection from this collection with some elements removed.

Creates a new collection from this collection with some elements removed.

This method takes two or more elements to be removed. Another overloaded variant of this method handles the case where a single element is removed.

elem1

the first element to remove.

elem2

the second element to remove.

elems

the remaining elements to remove.

returns

a new collection that contains all elements of the current collection except one less occurrence of each of the given elements.

Definition Classes
Subtractable
9. abstract def -(key: K): collection.Map[K, V]

[use case] Removes a key from this map, returning a new map.

[use case]

Removes a key from this map, returning a new map.

key

the key to be removed

returns

a new map without a binding for `key`

Definition Classes
MapLikeSubtractableGenMapLike
Full Signature

#### abstract def -(key: K): Map[K, V]

10. def --(xs: GenTraversableOnce[K]): Map[K, V]

Creates a new collection from this collection by removing all elements of another collection.

Creates a new collection from this collection by removing all elements of another collection.

xs

the collection containing the removed elements.

returns

a new collection that contains all elements of the current collection except one less occurrence of each of the elements of `elems`.

Definition Classes
Subtractable
11. def ->[B](y: B): (Map[K, V], B)
Implicit
This member is added by an implicit conversion from Map[K, V] to ArrowAssoc[Map[K, V]] performed by method ArrowAssoc in scala.Predef.
Definition Classes
ArrowAssoc
Annotations
()
12. final def ==(arg0: Any)

The expression `x == that` is equivalent to `if (x eq null) that eq null else x.equals(that)`.

The expression `x == that` is equivalent to `if (x eq null) that eq null else x.equals(that)`.

returns

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

Definition Classes
AnyRef → Any
13. def addString(, start: String, sep: String, end: String)

Appends all bindings of this map to a string builder using start, end, and separator strings.

Appends all bindings of this map to a string builder using start, end, and separator strings. The written text begins with the string `start` and ends with the string `end`. Inside, the string representations of all bindings of this map in the form of `key -> value` are separated by the string `sep`.

b

the builder to which strings are appended.

start

the starting string.

sep

the separator string.

end

the ending string.

returns

the string builder `b` to which elements were appended.

Definition Classes
MapLikeTraversableOnce

Appends all elements of this traversable or iterator to a string builder.

Appends all elements of this traversable or iterator to a string builder. The written text consists of the string representations (w.r.t. the method `toString`) of all elements of this traversable or iterator 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 =

h: StringBuilder = 1234```
b

the string builder to which elements are appended.

returns

the string builder `b` to which elements were appended.

Definition Classes
TraversableOnce

Appends all elements of this traversable or iterator to a string builder using a separator string.

Appends all elements of this traversable or iterator 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 traversable or iterator, 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 =

res0: StringBuilder = 1, 2, 3, 4```
b

the string builder to which elements are appended.

sep

the separator string.

returns

the string builder `b` to which elements were appended.

Definition Classes
TraversableOnce
16. def aggregate[B](z: ⇒ B)(seqop: (B, (K, V)) ⇒ B, combop: (B, B) ⇒ B): B

Aggregates the results of applying an operator to subsequent elements.

Aggregates the results of applying an operator to subsequent elements.

This is a more general form of `fold` and `reduce`. It is similar to `foldLeft` in that it doesn't require the result to be a supertype of the element type. In addition, it allows parallel collections to be processed in chunks, and then combines the intermediate results.

`aggregate` splits the traversable or iterator into partitions and processes each partition by sequentially applying `seqop`, starting with `z` (like `foldLeft`). Those intermediate results are then combined by using `combop` (like `fold`). The implementation of this operation may operate on an arbitrary number of collection partitions (even 1), so `combop` may be invoked an arbitrary number of times (even 0).

As an example, consider summing up the integer values of a list of chars. The initial value for the sum is 0. First, `seqop` transforms each input character to an Int and adds it to the sum (of the partition). Then, `combop` just needs to sum up the intermediate results of the partitions:

`List('a', 'b', 'c').aggregate(0)({ (sum, ch) => sum + ch.toInt }, { (p1, p2) => p1 + p2 })`
B

the type of accumulated results

z

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

seqop

an operator used to accumulate results within a partition

combop

an associative operator used to combine results from different partitions

Definition Classes
TraversableOnceGenTraversableOnce
17. def andThen[C](k: (V) ⇒ C): PartialFunction[K, C]

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.

C

the result type of the transformation function.

k

the transformation function

returns

a partial function with the same domain as this partial function, which maps arguments `x` to `k(this(x))`.

Definition Classes
PartialFunctionFunction1
18. def apply(key: K): V

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`.

key

the key

returns

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

Definition Classes
MapLikeGenMapLikeFunction1
19. def applyOrElse[K1 <: K, V1 >: V](x: K1, default: (K1) ⇒ V1): V1

Applies this partial function to the given argument when it is contained in the function domain.

Applies this partial function to the given argument when it is contained in the function domain. Applies fallback function where this partial function is not defined.

Note that expression `pf.applyOrElse(x, default)` is equivalent to

`if(pf isDefinedAt x) pf(x) else default(x)`

except that `applyOrElse` method can be implemented more efficiently. For all partial function literals the compiler generates an `applyOrElse` implementation which avoids double evaluation of pattern matchers and guards. This makes `applyOrElse` the basis for the efficient implementation for many operations and scenarios, such as:

• combining partial functions into `orElse`/`andThen` chains does not lead to excessive `apply`/`isDefinedAt` evaluation
• `lift` and `unlift` do not evaluate source functions twice on each invocation
• `runWith` allows efficient imperative-style combining of partial functions with conditionally applied actions

For non-literal partial function classes with nontrivial `isDefinedAt` method it is recommended to override `applyOrElse` with custom implementation that avoids double `isDefinedAt` evaluation. This may result in better performance and more predictable behavior w.r.t. side effects.

x

the function argument

default

the fallback function

returns

the result of this function or fallback function application.

Definition Classes
MapLikePartialFunction
Since

2.10

20. final def asInstanceOf[T0]: T0

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

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

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

returns

Definition Classes
Any
Exceptions thrown

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

21. def canEqual(that: Any)

Method called from equality methods, so that user-defined subclasses can refuse to be equal to other collections of the same kind.

Method called from equality methods, so that user-defined subclasses can refuse to be equal to other collections of the same kind.

that

The object with which this iterable collection should be compared

returns

`true`, if this iterable collection can possibly equal `that`, `false` otherwise. The test takes into consideration only the run-time types of objects but ignores their elements.

Definition Classes
IterableLikeEquals
22. def clone()

Create a copy of the receiver object.

Create a copy of the receiver object.

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

returns

a copy of the receiver object.

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

not specified by SLS as a member of AnyRef

23. def collect[B](pf: PartialFunction[A, B]): Map[B]

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

[use case]

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

B

the element type of the returned collection.

pf

the partial function which filters and maps the immutable map.

returns

a new immutable 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.

Definition Classes
TraversableLikeGenTraversableLike
Full Signature

#### def collect[B, That](pf: PartialFunction[(K, V), B])(implicit bf: CanBuildFrom[Map[K, V], B, That]): That

24. def collectFirst[B](pf: PartialFunction[(K, V), B]): Option[B]

Finds the first element of the traversable or iterator for which the given partial function is defined, and applies the partial function to it.

Finds the first element of the traversable or iterator 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.

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.

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

25. def companion

The factory companion object that builds instances of class `immutable.Iterable`.

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

Definition Classes
IterableIterableGenIterableTraversableTraversableGenTraversableGenericTraversableTemplate
26. def compose[A](g: (A) ⇒ K): (A) ⇒ V

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.

A

the type to which function `g` can be applied

g

a function A => T1

returns

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

Definition Classes
Function1
Annotations
()
27. def contains(key: K)

Tests whether this map contains a binding for a key.

Tests whether this map contains a binding for a key.

key

the key

returns

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

Definition Classes
MapLikeGenMapLike
28. def copyToArray(xs: Array[A], start: Int, len: Int): Unit

[use case] Copies the elements of this immutable map to an array.

[use case]

Copies the elements of this immutable map to an array. Fills the given array `xs` with at most `len` elements of this immutable map, starting at position `start`. Copying will stop once either the end of the current immutable map is reached, or the end of the target array is reached, or `len` elements have been copied.

xs

the array to fill.

start

the starting index.

len

the maximal number of elements to copy.

Definition Classes
IterableLikeTraversableLikeTraversableOnceGenTraversableOnce
Full Signature

#### def copyToArray[B >: (K, V)](xs: Array[B], start: Int, len: Int): Unit

29. def copyToArray(xs: Array[A]): Unit

[use case] Copies the elements of this immutable map to an array.

[use case]

Copies the elements of this immutable map to an array. Fills the given array `xs` with values of this immutable map. Copying will stop once either the end of the current immutable map is reached, or the end of the target array is reached.

xs

the array to fill.

Definition Classes
TraversableOnceGenTraversableOnce
Full Signature

#### def copyToArray[B >: (K, V)](xs: Array[B]): Unit

30. def copyToArray(xs: Array[A], start: Int): Unit

[use case] Copies the elements of this immutable map to an array.

[use case]

Copies the elements of this immutable map to an array. Fills the given array `xs` with values of this immutable map, beginning at index `start`. Copying will stop once either the end of the current immutable map is reached, or the end of the target array is reached.

xs

the array to fill.

start

the starting index.

Definition Classes
TraversableOnceGenTraversableOnce
Full Signature

#### def copyToArray[B >: (K, V)](xs: Array[B], start: Int): Unit

31. def copyToBuffer[B >: (K, V)](dest: Buffer[B]): Unit

Copies all elements of this traversable or iterator to a buffer.

Copies all elements of this traversable or iterator to a buffer.

Note: will not terminate for infinite-sized collections.

dest

The buffer to which elements are copied.

Definition Classes
TraversableOnce
32. def count(p: ((K, V)) ⇒ Boolean): Int

Counts the number of elements in the traversable or iterator which satisfy a predicate.

Counts the number of elements in the traversable or iterator which satisfy a predicate.

p

the predicate used to test elements.

returns

the number of elements satisfying the predicate `p`.

Definition Classes
TraversableOnceGenTraversableOnce
33. def default(key: K): V

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.

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.

key

the given key value for which a binding is missing.

Definition Classes
MapLikeGenMapLike
Exceptions thrown
34. def drop(n: Int): Map[K, V]

Selects all elements except first n ones.

Selects all elements except first n ones.

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

n

the number of elements to drop from this iterable collection.

returns

a iterable collection consisting of all elements of this iterable collection except the first `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.

Definition Classes
IterableLikeTraversableLikeGenTraversableLike
35. def dropRight(n: Int): Map[K, V]

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.

n

The number of elements to take

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.

Definition Classes
IterableLike
36. def dropWhile(p: ((K, V)) ⇒ Boolean): Map[K, V]

Drops longest prefix of elements that satisfy a predicate.

Drops longest prefix of elements that satisfy a predicate.

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

returns

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

Definition Classes
TraversableLikeGenTraversableLike
37. def empty: Map[K, V]

The empty map of the same type as this map

The empty map of the same type as this map

returns

an empty map of type `This`.

Definition Classes
MapMapMapLike
38. def ensuring(cond: (Map[K, V]) ⇒ Boolean, msg: ⇒ Any): Map[K, V]
Implicit
This member is added by an implicit conversion from Map[K, V] to Ensuring[Map[K, V]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
39. def ensuring(cond: (Map[K, V]) ⇒ Boolean): Map[K, V]
Implicit
This member is added by an implicit conversion from Map[K, V] to Ensuring[Map[K, V]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
40. def ensuring(cond: Boolean, msg: ⇒ Any): Map[K, V]
Implicit
This member is added by an implicit conversion from Map[K, V] to Ensuring[Map[K, V]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
41. def ensuring(cond: Boolean): Map[K, V]
Implicit
This member is added by an implicit conversion from Map[K, V] to Ensuring[Map[K, V]] performed by method Ensuring in scala.Predef.
Definition Classes
Ensuring
42. final def eq(arg0: AnyRef)

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

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

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

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

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

returns

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

Definition Classes
AnyRef
43. def equals(that: Any)

Compares two maps structurally; i.e., checks if all mappings contained in this map are also contained in the other map, and vice versa.

Compares two maps structurally; i.e., checks if all mappings contained in this map are also contained in the other map, and vice versa.

that

the other map

returns

`true` if both maps contain exactly the same mappings, `false` otherwise.

Definition Classes
GenMapLikeEquals → AnyRef → Any
44. def exists(p: ((K, V)) ⇒ Boolean)

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

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

Note: may not terminate for infinite-sized collections.

p

the predicate used to test elements.

returns

`false` if this iterable collection is empty, otherwise `true` if the given predicate `p` holds for some of the elements of this iterable collection, otherwise `false`

Definition Classes
IterableLikeTraversableLikeTraversableOnceGenTraversableOnce
45. def filter(p: ((K, V)) ⇒ Boolean): Map[K, V]

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

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

p

the predicate used to test elements.

returns

a new traversable collection consisting of all elements of this traversable collection that satisfy the given predicate `p`. The order of the elements is preserved.

Definition Classes
TraversableLikeGenTraversableLike
46. def filterKeys(p: (K) ⇒ Boolean): Map[K, V]

Filters this map by retaining only keys satisfying a predicate.

Filters this map by retaining only keys satisfying a predicate.

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
MapLikeMapLikeGenMapLike
47. def filterNot(p: ((K, V)) ⇒ Boolean): Map[K, V]

Returns a new map obtained by removing all key/value pairs for which the predicate `p` returns `true`.

Returns a new map obtained by removing all key/value pairs for which the predicate `p` returns `true`.

Note: This method works by successively removing elements for which the predicate is true from this set. If removal is slow, or you expect that most elements of the set will be removed, you might consider using `filter` with a negated predicate instead.

p

A predicate over key-value pairs

returns

A new map containing elements not satisfying the predicate.

Definition Classes
MapLikeTraversableLikeGenTraversableLike
48. def finalize(): Unit

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

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

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

Attributes
protected[lang]
Definition Classes
AnyRef
Annotations
( classOf[java.lang.Throwable] )
Note

not specified by SLS as a member of AnyRef

49. def find(p: ((K, V)) ⇒ Boolean): Option[(K, V)]

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

Finds the first element of the iterable 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.

p

the predicate used to test elements.

returns

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

Definition Classes
IterableLikeTraversableLikeTraversableOnceGenTraversableOnce
50. def flatMap[B](f: (A) ⇒ GenTraversableOnce[B]): Map[B]

[use case] Builds a new collection by applying a function to all elements of this immutable map and using the elements of the resulting collections.

[use case]

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

For example:

`def getWords(lines: Seq[String]): Seq[String] = lines flatMap (line => line split "\\W+")`

The type of the resulting collection is guided by the static type of immutable map. This might cause unexpected results sometimes. For example:

```// lettersOf will return a Seq[Char] of likely repeated letters, instead of a Set
def lettersOf(words: Seq[String]) = words flatMap (word => word.toSet)

// lettersOf will return a Set[Char], not a Seq
def lettersOf(words: Seq[String]) = words.toSet flatMap (word => word.toSeq)

// xs will be an Iterable[Int]
val xs = Map("a" -> List(11,111), "b" -> List(22,222)).flatMap(_._2)

// ys will be a Map[Int, Int]
val ys = Map("a" -> List(1 -> 11,1 -> 111), "b" -> List(2 -> 22,2 -> 222)).flatMap(_._2)```
B

the element type of the returned collection.

f

the function to apply to each element.

returns

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

Definition Classes
Full Signature

#### def flatMap[B, That](f: ((K, V)) ⇒ GenTraversableOnce[B])(implicit bf: CanBuildFrom[Map[K, V], B, That]): That

51. def flatten[B]: Map[B]

[use case] Converts this immutable map of traversable collections into a immutable map formed by the elements of these traversable collections.

[use case]

Converts this immutable map of traversable collections into a immutable map formed by the elements of these traversable collections.

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

```val xs = List(
Set(1, 2, 3),
Set(1, 2, 3)
).flatten
// xs == List(1, 2, 3, 1, 2, 3)

val ys = Set(
List(1, 2, 3),
List(3, 2, 1)
).flatten
// ys == Set(1, 2, 3)```
B

the type of the elements of each traversable collection.

returns

a new immutable map resulting from concatenating all element immutable maps.

Definition Classes
GenericTraversableTemplate
Full Signature

#### def flatten[B](implicit asTraversable: ((K, V)) ⇒ GenTraversableOnce[B]): Iterable[B]

52. def fold[A1 >: (K, V)](z: A1)(op: (A1, A1) ⇒ A1): A1

Folds the elements of this traversable or iterator using the specified associative binary operator.

Folds the elements of this traversable or iterator using the specified associative binary operator.

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

Note: will not terminate for infinite-sized collections.

A1

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

z

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

op

a binary operator that must be associative.

returns

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

Definition Classes
TraversableOnceGenTraversableOnce
53. def foldLeft[B](z: B)(op: (B, (K, V)) ⇒ B): B

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

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

Note: will not terminate for infinite-sized collections.

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

B

the result type of the binary operator.

z

the start value.

op

the binary operator.

returns

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

`op(...op(z, x_1), x_2, ..., x_n)`

where `x1, ..., xn` are the elements of this traversable or iterator. Returns `z` if this traversable or iterator is empty.

Definition Classes
TraversableOnceGenTraversableOnce
54. def foldRight[B](z: B)(op: ((K, V), B) ⇒ B): B

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

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

Note: will not terminate for infinite-sized collections.

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

B

the result type of the binary operator.

z

the start value.

op

the binary operator.

returns

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

`op(x_1, op(x_2, ... op(x_n, z)...))`

where `x1, ..., xn` are the elements of this iterable collection. Returns `z` if this iterable collection is empty.

Definition Classes
IterableLikeTraversableOnceGenTraversableOnce
55. def forall(p: ((K, V)) ⇒ Boolean)

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

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

Note: may not terminate for infinite-sized collections.

p

the predicate used to test elements.

returns

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

Definition Classes
IterableLikeTraversableLikeTraversableOnceGenTraversableOnce
56. def foreach(f: ((K, V)) ⇒ Unit): Unit

[use case] Applies a function `f` to all elements of this immutable map.

[use case]

Applies a function `f` to all elements of this immutable map.

Note: this method underlies the implementation of most other bulk operations. Subclasses should re-implement this method if a more efficient implementation exists.

f

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

Definition Classes
Full Signature

#### def foreach[U](f: ((K, V)) ⇒ U): Unit

57. def genericBuilder[B]: Builder[B, Iterable[B]]

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

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

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

Returns the runtime class representation of the object.

Returns the runtime class representation of the object.

returns

a class object corresponding to the runtime type of the receiver.

Definition Classes
AnyRef → Any
Annotations
()
59. def getOrElse(key: K, default: ⇒ V): V

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

[use case]

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

key

the key.

default

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

returns

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

Definition Classes
MapLikeGenMapLike
Full Signature

#### def getOrElse[V1 >: V](key: K, default: ⇒ V1): V1

60. def groupBy[K](f: ((K, V)) ⇒ K): Map[K, Map[K, V]]

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

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

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

K

the type of keys returned by the discriminator function.

f

the discriminator function.

returns

A map from keys to traversable 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 traversable collection of those elements `x` for which `f(x)` equals `k`.

Definition Classes
TraversableLikeGenTraversableLike
61. def grouped(size: Int): Iterator[Map[K, V]]

Partitions elements in fixed size iterable collections.

Partitions elements in fixed size iterable collections.

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.

Definition Classes
IterableLike

scala.collection.Iterator, method `grouped`

62. def hasDefiniteSize

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

Tests whether this traversable 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.

Definition Classes
TraversableLikeTraversableOnceGenTraversableOnce
63. def hashCode(): Int

The hashCode method for reference types.

The hashCode method for reference types. See hashCode in scala.Any.

returns

the hash code value for this object.

Definition Classes
GenMapLike → AnyRef → Any

Selects the first element of this iterable collection.

Selects the first element of this iterable collection.

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

returns

the first element of this iterable collection.

Definition Classes
IterableLikeTraversableLikeGenTraversableLike
Exceptions thrown

`NoSuchElementException` if the iterable collection is empty.

Optionally selects the first element.

Optionally selects the first element.

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

returns

the first element of this traversable collection if it is nonempty, `None` if it is empty.

Definition Classes
TraversableLikeGenTraversableLike
66. def init: Map[K, V]

Selects all elements except the last.

Selects all elements except the last.

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

returns

a traversable collection consisting of all elements of this traversable collection except the last one.

Definition Classes
TraversableLikeGenTraversableLike
Exceptions thrown

`UnsupportedOperationException` if the traversable collection is empty.

67. def inits: Iterator[Map[K, V]]

Iterates over the inits of this traversable collection.

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

returns

an iterator over all the inits of this traversable collection

Definition Classes
TraversableLike
Example:
1. `List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)`

68. def isDefinedAt(key: K)

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`.

key

the key

returns

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

Definition Classes
MapLikeGenMapLikePartialFunction
69. def isEmpty

Tests whether the map is empty.

Tests whether the map is empty.

returns

`true` if the map does not contain any key/value binding, `false` otherwise.

Definition Classes
MapLikeIterableLikeTraversableLikeTraversableOnceGenTraversableOnce
70. final def isInstanceOf[T0]

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

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

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

returns

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

Definition Classes
Any
71. final def isTraversableAgain

Tests whether this traversable collection can be repeatedly traversed.

Tests whether this traversable collection can be repeatedly traversed.

returns

`true`

Definition Classes
TraversableLikeGenTraversableLikeGenTraversableOnce
72. def keySet: Set[K]

Collects all keys of this map in a set.

Collects all keys of this map in a set.

returns

a set containing all keys of this map.

Definition Classes
MapLikeMapLikeGenMapLike
73. def keys

Collects all keys of this map in an iterable collection.

Collects all keys of this map in an iterable collection.

returns

the keys of this map as an iterable.

Definition Classes
MapLikeGenMapLike
Annotations
@migration
Migration

(Changed in version 2.8.0) `keys` returns `Iterable[K]` rather than `Iterator[K]`.

74. def keysIterator: Iterator[K]

Creates an iterator for all keys.

Creates an iterator for all keys.

returns

an iterator over all keys.

Definition Classes
MapLikeGenMapLike
75. def last: (K, V)

Selects the last element.

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 traversable collection.

Definition Classes
TraversableLikeGenTraversableLike
Exceptions thrown

`NoSuchElementException` If the traversable collection is empty.

76. def lastOption: Option[(K, V)]

Optionally selects the last element.

Optionally selects the last element.

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

returns

the last element of this traversable collection\$ if it is nonempty, `None` if it is empty.

Definition Classes
TraversableLikeGenTraversableLike
77. def lift: (K) ⇒ Option[V]

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.

Definition Classes
PartialFunction

Function.unlift

78. def map[B](f: (A) ⇒ B): Map[B]

[use case] Builds a new collection by applying a function to all elements of this immutable map.

[use case]

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

B

the element type of the returned collection.

f

the function to apply to each element.

returns

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

Definition Classes
Full Signature

#### def map[B, That](f: ((K, V)) ⇒ B)(implicit bf: CanBuildFrom[Map[K, V], B, That]): That

79. def mapValues[W](f: (V) ⇒ W): Map[K, W]

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

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

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
MapLikeMapLikeGenMapLike
80. def max: A

[use case] Finds the largest element.

[use case]

Finds the largest element.

returns

the largest element of this immutable map.

Definition Classes
TraversableOnceGenTraversableOnce
Full Signature

#### def max[B >: (K, V)](implicit cmp: Ordering[B]): (K, V)

Exceptions thrown

`UnsupportedOperationException` if this immutable map is empty.

81. def maxBy[B](f: (A) ⇒ B): A

[use case] Finds the first element which yields the largest value measured by function f.

[use case]

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

B

The result type of the function f.

f

The measuring function.

returns

the first element of this immutable map with the largest value measured by function f.

Definition Classes
TraversableOnceGenTraversableOnce
Full Signature

#### def maxBy[B](f: ((K, V)) ⇒ B)(implicit cmp: Ordering[B]): (K, V)

Exceptions thrown

`UnsupportedOperationException` if this immutable map is empty.

82. def min: A

[use case] Finds the smallest element.

[use case]

Finds the smallest element.

returns

the smallest element of this immutable map

Definition Classes
TraversableOnceGenTraversableOnce
Full Signature

#### def min[B >: (K, V)](implicit cmp: Ordering[B]): (K, V)

Exceptions thrown

`UnsupportedOperationException` if this immutable map is empty.

83. def minBy[B](f: (A) ⇒ B): A

[use case] Finds the first element which yields the smallest value measured by function f.

[use case]

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

B

The result type of the function f.

f

The measuring function.

returns

the first element of this immutable map with the smallest value measured by function f.

Definition Classes
TraversableOnceGenTraversableOnce
Full Signature

#### def minBy[B](f: ((K, V)) ⇒ B)(implicit cmp: Ordering[B]): (K, V)

Exceptions thrown

`UnsupportedOperationException` if this immutable map is empty.

84. def mkString

Displays all elements of this traversable or iterator in a string.

Displays all elements of this traversable or iterator in a string.

returns

a string representation of this traversable or iterator. In the resulting string the string representations (w.r.t. the method `toString`) of all elements of this traversable or iterator follow each other without any separator string.

Definition Classes
TraversableOnceGenTraversableOnce
85. def mkString(sep: String)

Displays all elements of this traversable or iterator in a string using a separator string.

Displays all elements of this traversable or iterator in a string using a separator string.

sep

the separator string.

returns

a string representation of this traversable or iterator. In the resulting string the string representations (w.r.t. the method `toString`) of all elements of this traversable or iterator are separated by the string `sep`.

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

86. def mkString(start: String, sep: String, end: String)

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

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

start

the starting string.

sep

the separator string.

end

the ending string.

returns

a string representation of this traversable or iterator. 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 traversable or iterator are separated by the string `sep`.

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

87. final def ne(arg0: AnyRef)

Equivalent to `!(this eq that)`.

Equivalent to `!(this eq that)`.

returns

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

Definition Classes
AnyRef
88. def newBuilder: Builder[(K, V), Map[K, V]]

A common implementation of `newBuilder` for all maps in terms of `empty`.

A common implementation of `newBuilder` for all maps in terms of `empty`. Overridden for mutable maps in `mutable.MapLike`.

Attributes
protected[this]
Definition Classes
MapLikeTraversableLikeHasNewBuilder
89. def nonEmpty

Tests whether the traversable or iterator is not empty.

Tests whether the traversable or iterator is not empty.

returns

`true` if the traversable or iterator contains at least one element, `false` otherwise.

Definition Classes
TraversableOnceGenTraversableOnce
90. final def notify(): Unit

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

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

Definition Classes
AnyRef
Annotations
()
Note

not specified by SLS as a member of AnyRef

91. final def notifyAll(): Unit

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

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

Definition Classes
AnyRef
Annotations
()
Note

not specified by SLS as a member of AnyRef

92. def orElse[A1 <: K, B1 >: V](that: PartialFunction[A1, B1]): PartialFunction[A1, B1]

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.

A1

the argument type of the fallback function

B1

the result type of the fallback function

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.

Definition Classes
PartialFunction
93. def par: ParMap[K, V]

Returns a parallel implementation of this collection.

Returns a parallel implementation of this collection.

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

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

All parallel collections return a reference to themselves.

returns

a parallel implementation of this collection

Definition Classes
Parallelizable
94. def parCombiner: Combiner[(K, V), ParMap[K, V]]

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

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

returns

a combiner for the parallel collection of type `ParRepr`

Attributes
protected[this]
Definition Classes
MapLikeMapLikeTraversableLikeParallelizable
95. def partition(p: ((K, V)) ⇒ Boolean): (Map[K, V], Map[K, V])

Partitions this traversable collection in two traversable collections according to a predicate.

Partitions this traversable collection in two traversable collections according to a predicate.

p

the predicate on which to partition.

returns

a pair of traversable collections: the first traversable collection consists of all elements that satisfy the predicate `p` and the second traversable collection consists of all elements that don't. The relative order of the elements in the resulting traversable collections is the same as in the original traversable collection.

Definition Classes
TraversableLikeGenTraversableLike
96. def product: A

[use case] Multiplies up the elements of this collection.

[use case]

Multiplies up the elements of this collection.

returns

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

Definition Classes
TraversableOnceGenTraversableOnce
Full Signature

#### def product[B >: (K, V)](implicit num: Numeric[B]): B

97. def reduce[A1 >: (K, V)](op: (A1, A1) ⇒ A1): A1

Reduces the elements of this traversable or iterator using the specified associative binary operator.

Reduces the elements of this traversable or iterator using the specified associative binary operator.

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

A1

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

op

A binary operator that must be associative.

returns

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

Definition Classes
TraversableOnceGenTraversableOnce
Exceptions thrown

`UnsupportedOperationException` if this traversable or iterator is empty.

98. def reduceLeft[B >: (K, V)](op: (B, (K, V)) ⇒ B): B

Applies a binary operator to all elements of this traversable or iterator, going left to right.

Applies a binary operator to all elements of this traversable or iterator, going left to right.

Note: will not terminate for infinite-sized collections.

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

B

the result type of the binary operator.

op

the binary operator.

returns

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

`op( op( ... op(x_1, x_2) ..., x_{n-1}), x_n)`

where `x1, ..., xn` are the elements of this traversable or iterator.

Definition Classes
TraversableOnce
Exceptions thrown

`UnsupportedOperationException` if this traversable or iterator is empty.

99. def reduceLeftOption[B >: (K, V)](op: (B, (K, V)) ⇒ B): Option[B]

Optionally applies a binary operator to all elements of this traversable or iterator, going left to right.

Optionally applies a binary operator to all elements of this traversable or iterator, going left to right.

Note: will not terminate for infinite-sized collections.

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

B

the result type of the binary operator.

op

the binary operator.

returns

an option value containing the result of `reduceLeft(op)` if this traversable or iterator is nonempty, `None` otherwise.

Definition Classes
TraversableOnceGenTraversableOnce
100. def reduceOption[A1 >: (K, V)](op: (A1, A1) ⇒ A1): Option[A1]

Reduces the elements of this traversable or iterator, if any, using the specified associative binary operator.

Reduces the elements of this traversable or iterator, if any, using the specified associative binary operator.

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

A1

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

op

A binary operator that must be associative.

returns

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

Definition Classes
TraversableOnceGenTraversableOnce
101. def reduceRight[B >: (K, V)](op: ((K, V), B) ⇒ B): B

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

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

Note: will not terminate for infinite-sized collections.

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

B

the result type of the binary operator.

op

the binary operator.

returns

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

`op(x_1, op(x_2, ..., op(x_{n-1}, x_n)...))`

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

Definition Classes
IterableLikeTraversableOnceGenTraversableOnce
Exceptions thrown

`UnsupportedOperationException` if this iterable collection is empty.

102. def reduceRightOption[B >: (K, V)](op: ((K, V), B) ⇒ B): Option[B]

Optionally applies a binary operator to all elements of this traversable or iterator, going right to left.

Optionally applies a binary operator to all elements of this traversable or iterator, going right to left.

Note: will not terminate for infinite-sized collections.

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

B

the result type of the binary operator.

op

the binary operator.

returns

an option value containing the result of `reduceRight(op)` if this traversable or iterator is nonempty, `None` otherwise.

Definition Classes
TraversableOnceGenTraversableOnce
103. def repr: Map[K, V]

The collection of type traversable collection underlying this `TraversableLike` object.

The collection of type traversable collection underlying this `TraversableLike` object. By default this is implemented as the `TraversableLike` object itself, but this can be overridden.

Definition Classes
TraversableLikeGenTraversableLike
104. def reversed: scala.List[(K, V)]
Attributes
protected[this]
Definition Classes
TraversableOnce
105. def runWith[U](action: (V) ⇒ U): (K) ⇒ Boolean

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.

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.

Definition Classes
PartialFunction
Since

2.10

`applyOrElse`.

106. def sameElements(that: GenIterable[A])

[use case] Checks if the other iterable collection contains the same elements in the same order as this immutable map.

[use case]

Checks if the other iterable collection contains the same elements in the same order as this immutable map.

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

that

the collection to compare with.

returns

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

Definition Classes
IterableLikeGenIterableLike
Full Signature

#### def sameElements[B >: (K, V)](that: GenIterable[B]): Boolean

107. def scan[B >: (K, V), That](z: B)(op: (B, B) ⇒ B)(implicit cbf: CanBuildFrom[Map[K, V], B, That]): That

Computes a prefix scan of the elements of the collection.

Computes a prefix scan of the elements of the collection.

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

B

element type of the resulting collection

That

type of the resulting collection

z

neutral element for the operator `op`

op

the associative operator for the scan

cbf

combiner factory which provides a combiner

returns

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

Definition Classes
TraversableLikeGenTraversableLike
108. def scanLeft[B, That](z: B)(op: (B, (K, V)) ⇒ B)(implicit bf: CanBuildFrom[Map[K, V], B, That]): That

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

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

Note: will not terminate for infinite-sized collections.

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

B

the type of the elements in the resulting collection

That

the actual type of the resulting collection

z

the initial value

op

the binary operator applied to the intermediate result and the element

bf

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

returns

collection with intermediate results

Definition Classes
TraversableLikeGenTraversableLike
109. def scanRight[B, That](z: B)(op: ((K, V), B) ⇒ B)(implicit bf: CanBuildFrom[Map[K, V], B, That]): That

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.

Example:

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

the type of the elements in the resulting collection

That

the actual type of the resulting collection

z

the initial value

op

the binary operator applied to the intermediate result and the element

bf

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

returns

collection with intermediate results

Definition Classes
TraversableLikeGenTraversableLike
Annotations
@migration
Migration

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

110. def seq: Map[K, V]

A version of this collection with all of the operations implemented sequentially (i.e., in a single-threaded manner).

A version of this collection with all of the operations implemented sequentially (i.e., in a single-threaded manner).

This method returns a reference to this collection. In parallel collections, it is redefined to return a sequential implementation of this collection. In both cases, it has O(1) complexity.

returns

a sequential view of the collection.

Definition Classes
MapMapGenMapGenMapLikeIterableIterableGenIterableTraversableTraversableGenTraversableParallelizableTraversableOnceGenTraversableOnce
111. def size: Int

The size of this traversable or iterator.

The size of this traversable or iterator.

Note: will not terminate for infinite-sized collections.

returns

the number of elements in this traversable or iterator.

Definition Classes
TraversableOnceGenTraversableOnce
112. def sizeHintIfCheap: Int

The size of this collection or iterator, if it can be cheaply computed

The size of this collection or iterator, if it can be cheaply computed

returns

the number of elements in this collection or iterator, or -1 if the size cannot be determined cheaply

Attributes
protected[collection]
Definition Classes
GenTraversableOnce
113. def slice(from: Int, until: Int): Map[K, V]

Selects an interval of elements.

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

`from <= indexOf(x) < until`

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

returns

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

Definition Classes
IterableLikeTraversableLikeGenTraversableLike
114. def sliding(size: Int, step: Int): Iterator[Map[K, V]]

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.)

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 truncated if there are fewer than `size` elements remaining to be grouped.

Definition Classes
IterableLike

scala.collection.Iterator, method `sliding`

115. def sliding(size: Int): Iterator[Map[K, V]]

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

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

size

the number of elements per group

returns

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

Definition Classes
IterableLike

scala.collection.Iterator, method `sliding`

116. def span(p: ((K, V)) ⇒ Boolean): (Map[K, V], Map[K, V])

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

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

Note: `c span p` is equivalent to (but possibly more efficient than) `(c takeWhile p, c dropWhile p)`, provided the evaluation of the predicate `p` does not cause any side-effects.

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

returns

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

Definition Classes
TraversableLikeGenTraversableLike
117. def splitAt(n: Int): (Map[K, V], Map[K, V])

Splits this traversable collection into two at a given position.

Splits this traversable collection into two at a given position. Note: `c splitAt n` is equivalent to (but possibly more efficient than) `(c take n, c drop n)`.

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

n

the position at which to split.

returns

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

Definition Classes
TraversableLikeGenTraversableLike
118. def stringPrefix

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

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

returns

a string representation which starts the result of `toString` applied to this map. Unless overridden in subclasses, the string prefix of every map is `"Map"`.

Definition Classes
MapLikeTraversableLikeGenTraversableLike
119. def sum: A

[use case] Sums up the elements of this collection.

[use case]

Sums up the elements of this collection.

returns

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

Definition Classes
TraversableOnceGenTraversableOnce
Full Signature

#### def sum[B >: (K, V)](implicit num: Numeric[B]): B

120. final def synchronized[T0](arg0: ⇒ T0): T0
Definition Classes
AnyRef
121. def tail: Map[K, V]

Selects all elements except the first.

Selects all elements except the first.

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

returns

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

Definition Classes
TraversableLikeGenTraversableLike
Exceptions thrown

`java.lang.UnsupportedOperationException` if the traversable collection is empty.

122. def tails: Iterator[Map[K, V]]

Iterates over the tails of this traversable collection.

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

returns

an iterator over all the tails of this traversable collection

Definition Classes
TraversableLike
Example:
1. `List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)`

123. def take(n: Int): Map[K, V]

Selects first n elements.

Selects first n elements.

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

n

the number of elements to take from this iterable collection.

returns

a iterable collection consisting only of the first `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.

Definition Classes
IterableLikeTraversableLikeGenTraversableLike
124. def takeRight(n: Int): Map[K, V]

Selects last n elements.

Selects last n elements.

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

n

the number of elements to take

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.

Definition Classes
IterableLike
125. def takeWhile(p: ((K, V)) ⇒ Boolean): Map[K, V]

Takes longest prefix of elements that satisfy a predicate.

Takes longest prefix of elements that satisfy a predicate.

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

returns

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

Definition Classes
IterableLikeTraversableLikeGenTraversableLike
126. def thisCollection: collection.Iterable[(K, V)]

The underlying collection seen as an instance of `Iterable`.

The underlying collection seen as an instance of `Iterable`. By default this is implemented as the current collection object itself, but this can be overridden.

Attributes
protected[this]
Definition Classes
IterableLikeTraversableLike
127. def to[Col[_]]: Col[A]

[use case] Converts this immutable map into another by copying all elements.

[use case]

Converts this immutable map into another by copying all elements.

Col

The collection type to build.

returns

a new collection containing all elements of this immutable map.

Definition Classes
TraversableLikeTraversableOnceGenTraversableOnce
Full Signature

#### def to[Col[_]](implicit cbf: CanBuildFrom[Nothing, (K, V), Col[(K, V)]]): Col[(K, V)]

128. def toArray: Array[A]

[use case] Converts this immutable map to an array.

[use case]

Converts this immutable map to an array.

returns

an array containing all elements of this immutable map. An `ClassTag` must be available for the element type of this immutable map.

Definition Classes
TraversableOnceGenTraversableOnce
Full Signature

#### def toArray[B >: (K, V)](implicit arg0: ClassTag[B]): Array[B]

129. def toBuffer[E >: (K, V)]: Buffer[E]

Uses the contents of this map to create a new mutable buffer.

Uses the contents of this map to create a new mutable buffer.

returns

a buffer containing all elements of this map.

Definition Classes
MapLikeTraversableOnceGenTraversableOnce
130. def toCollection(repr: Map[K, V]): collection.Iterable[(K, V)]

A conversion from collections of type `Repr` to `Iterable` objects.

A conversion from collections of type `Repr` to `Iterable` objects. By default this is implemented as just a cast, but this can be overridden.

Attributes
protected[this]
Definition Classes
IterableLikeTraversableLike
131. def toIndexedSeq: IndexedSeq[(K, V)]

Converts this traversable or iterator to an indexed sequence.

Converts this traversable or iterator to an indexed sequence.

Note: will not terminate for infinite-sized collections.

returns

an indexed sequence containing all elements of this traversable or iterator.

Definition Classes
TraversableOnceGenTraversableOnce
132. def toIterable: collection.Iterable[(K, V)]

Returns this iterable collection as an iterable collection.

Returns this iterable collection as an iterable collection.

A new collection will not be built; lazy collections will stay lazy.

Note: will not terminate for infinite-sized collections.

returns

an `Iterable` containing all elements of this iterable collection.

Definition Classes
IterableLikeTraversableOnceGenTraversableOnce
133. def toIterator: Iterator[(K, V)]

Returns an Iterator over the elements in this iterable collection.

Returns an Iterator over the elements in this iterable collection. Produces the same result as `iterator`.

Note: will not terminate for infinite-sized collections.

returns

an Iterator containing all elements of this iterable collection.

Definition Classes
IterableLikeTraversableLikeGenTraversableOnce
Annotations
( message = ... , since = "2.11.0" )
134. def toList: scala.List[(K, V)]

Converts this traversable or iterator to a list.

Converts this traversable or iterator to a list.

Note: will not terminate for infinite-sized collections.

returns

a list containing all elements of this traversable or iterator.

Definition Classes
TraversableOnceGenTraversableOnce
135. def toMap[T, U](implicit ev: <:<[(K, V), (T, U)]): Map[T, U]

Returns this immutable map as an immutable map.

Returns this immutable map as an immutable map.

A new map will not be built; lazy collections will stay lazy.

returns

a map containing all elements of this immutable map.

Definition Classes
MapTraversableOnceGenTraversableOnce
Annotations
( message = ... , since = "2.11.0" )
136. def toParArray: ParArray[T]
Implicit
This member is added by an implicit conversion from Map[K, V] to CollectionsHaveToParArray[Map[K, V], T] performed by method CollectionsHaveToParArray in scala.collection.parallel. This conversion will take place only if an implicit value of type (Map[K, V]) ⇒ GenTraversableOnce[T] is in scope.
Definition Classes
CollectionsHaveToParArray
137. def toSeq: collection.Seq[(K, V)]

Converts this map to a sequence.

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

returns

a sequence containing all elements of this map.

Definition Classes
MapLikeTraversableOnceGenTraversableOnce
138. def toSet[B >: (K, V)]: Set[B]

Converts this traversable or iterator to a set.

Converts this traversable or iterator to a set.

Note: will not terminate for infinite-sized collections.

returns

a set containing all elements of this traversable or iterator.

Definition Classes
TraversableOnceGenTraversableOnce
139. def toStream: Stream[(K, V)]

Converts this iterable collection to a stream.

Converts this iterable collection to a stream.

returns

a stream containing all elements of this iterable collection.

Definition Classes
IterableLikeTraversableLikeGenTraversableOnce
140. def toString()

Converts this map to a string.

Converts this map to a string.

returns

a string representation of this collection. By default this string consists of the `stringPrefix` of this map, followed by all elements separated by commas and enclosed in parentheses.

Definition Classes
MapLikeTraversableLikeFunction1 → AnyRef → Any
141. def toTraversable: collection.Traversable[(K, V)]

Converts this traversable collection to an unspecified Traversable.

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

Note: will not terminate for infinite-sized collections.

returns

a Traversable containing all elements of this traversable collection.

Definition Classes
TraversableLikeTraversableOnceGenTraversableOnce
Annotations
( message = ... , since = "2.11.0" )
142. def toVector: scala.Vector[(K, V)]

Converts this traversable or iterator to a Vector.

Converts this traversable or iterator to a Vector.

Note: will not terminate for infinite-sized collections.

returns

a vector containing all elements of this traversable or iterator.

Definition Classes
TraversableOnceGenTraversableOnce
143. def transform[W, That](f: (K, V) ⇒ W)(implicit bf: CanBuildFrom[Map[K, V], (K, W), That]): That

This function transforms all the values of mappings contained in this map with function `f`.

This function transforms all the values of mappings contained in this map with function `f`.

f

A function over keys and values

returns

the updated map

Definition Classes
MapLike
144. def transpose[B](implicit asTraversable: ((K, V)) ⇒ GenTraversableOnce[B]): Iterable[Iterable[B]]

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

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

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

the type of the elements of each traversable collection.

asTraversable

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

returns

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

Definition Classes
GenericTraversableTemplate
Annotations
@migration
Migration

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

Exceptions thrown

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

145. def unzip[A1, A2](implicit asPair: ((K, V)) ⇒ (A1, A2)): (Iterable[A1], Iterable[A2])

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

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

```val xs = Traversable(
(1, "one"),
(2, "two"),
(3, "three")).unzip
// xs == (Traversable(1, 2, 3),
//        Traversable(one, two, three))```
A1

the type of the first half of the element pairs

A2

the type of the second half of the element pairs

asPair

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

returns

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

Definition Classes
GenericTraversableTemplate
146. def unzip3[A1, A2, A3](implicit asTriple: ((K, V)) ⇒ (A1, A2, A3)): (Iterable[A1], Iterable[A2], Iterable[A3])

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

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

```val xs = Traversable(
(1, "one", '1'),
(2, "two", '2'),
(3, "three", '3')).unzip3
// xs == (Traversable(1, 2, 3),
//        Traversable(one, two, three),
//        Traversable(1, 2, 3))```
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

asTriple

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

returns

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

Definition Classes
GenericTraversableTemplate
147. def updated[V1 >: V](key: K, value: V1): Map[K, V1]

A new immutable map updating this map with a given key/value mapping.

A new immutable map updating this map with a given key/value mapping.

V1

the type of the added value

key

the key

value

the value

returns

A new map with the new key/value mapping

Definition Classes
MapLikeMapLike
148. def values

Collects all values of this map in an iterable collection.

Collects all values of this map in an iterable collection.

returns

the values of this map as an iterable.

Definition Classes
MapLikeGenMapLike
Annotations
@migration
Migration

(Changed in version 2.8.0) `values` returns `Iterable[V]` rather than `Iterator[V]`.

149. def valuesIterator: Iterator[V]

Creates an iterator for all values in this map.

Creates an iterator for all values in this map.

returns

an iterator over all values that are associated with some key in this map.

Definition Classes
MapLikeGenMapLike
150. def view(from: Int, until: Int): IterableView[(K, V), Map[K, V]]

Creates a non-strict view of a slice of this iterable collection.

Creates a non-strict view of a slice of this iterable collection.

Note: the difference between `view` and `slice` is that `view` produces a view of the current iterable collection, whereas `slice` produces a new iterable collection.

Note: `view(from, to)` is equivalent to `view.slice(from, to)`

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

from

the index of the first element of the view

until

the index of the element following the view

returns

a non-strict view of a slice of this iterable collection, starting at index `from` and extending up to (but not including) index `until`.

Definition Classes
IterableLikeTraversableLike
151. def view: IterableView[(K, V), Map[K, V]]

Creates a non-strict view of this iterable collection.

Creates a non-strict view of this iterable collection.

returns

a non-strict view of this iterable collection.

Definition Classes
IterableLikeTraversableLike
152. final def wait(): Unit
Definition Classes
AnyRef
Annotations
( ... )
153. final def wait(arg0: Long, arg1: Int): Unit
Definition Classes
AnyRef
Annotations
( ... )
154. final def wait(arg0: Long): Unit
Definition Classes
AnyRef
Annotations
( ... ) ()
155. def withDefault[V1 >: V](d: (K) ⇒ V1): Map[K, V1]

The same map with a given default function.

The same map with a given default function. Note: `get`, `contains`, `iterator`, `keys`, etc are not affected by `withDefault`.

Invoking transformer methods (e.g. `map`) will not preserve the default value.

d

the function mapping keys to values, used for non-present keys

returns

a wrapper of the map with a default value

156. def withDefaultValue[V1 >: V](d: V1): Map[K, V1]

The same map with a given default value.

The same map with a given default value. Note: `get`, `contains`, `iterator`, `keys`, etc are not affected by `withDefaultValue`.

Invoking transformer methods (e.g. `map`) will not preserve the default value.

d

default value used for non-present keys

returns

a wrapper of the map with a default value

157. def withFilter(p: ((K, V)) ⇒ Boolean): FilterMonadic[(K, V), Map[K, V]]

Creates a non-strict filter of this traversable collection.

Creates a non-strict filter of this traversable collection.

Note: the difference between `c filter p` and `c withFilter p` is that the former creates a new collection, whereas the latter only restricts the domain of subsequent `map`, `flatMap`, `foreach`, and `withFilter` operations.

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

p

the predicate used to test elements.

returns

an object of class `WithFilter`, which supports `map`, `flatMap`, `foreach`, and `withFilter` operations. All these operations apply to those elements of this traversable collection which satisfy the predicate `p`.

Definition Classes
158. def zip[B](that: GenIterable[B]): Map[(A, B)]

[use case] Returns a immutable map formed from this immutable map and another iterable collection by combining corresponding elements in pairs.

[use case]

Returns a immutable map formed from this immutable map 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.

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

B

the type of the second half of the returned pairs

that

The iterable providing the second half of each result pair

returns

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

Definition Classes
IterableLikeGenIterableLike
Full Signature

#### def zip[A1 >: (K, V), B, That](that: GenIterable[B])(implicit bf: CanBuildFrom[Map[K, V], (A1, B), That]): That

159. def zipAll[B](that: collection.Iterable[B], thisElem: A, thatElem: B): Map[(A, B)]

[use case] Returns a immutable map formed from this immutable map and another iterable collection by combining corresponding elements in pairs.

[use case]

Returns a immutable map formed from this immutable map 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.

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

B

the type of the second half of the returned pairs

that

The iterable providing the second half of each result pair

thisElem

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

thatElem

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

returns

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

Definition Classes
IterableLikeGenIterableLike
Full Signature

#### def zipAll[B, A1 >: (K, V), That](that: GenIterable[B], thisElem: A1, thatElem: B)(implicit bf: CanBuildFrom[Map[K, V], (A1, B), That]): That

160. def zipWithIndex: Map[(A, Int)]

[use case] Zips this immutable map with its indices.

[use case]

Zips this immutable map with its indices.

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

returns

A new immutable map containing pairs consisting of all elements of this immutable map paired with their index. Indices start at `0`.

Definition Classes
IterableLikeGenIterableLike
Full Signature

#### def zipWithIndex[A1 >: (K, V), That](implicit bf: CanBuildFrom[Map[K, V], (A1, Int), That]): That

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

161. def [B](y: B): (Map[K, V], B)
Implicit
This member is added by an implicit conversion from Map[K, V] to ArrowAssoc[Map[K, V]] performed by method ArrowAssoc in scala.Predef.
Definition Classes
ArrowAssoc

1. def +(other: String)
Implicit
This member is added by an implicit conversion from Map[K, V] to any2stringadd[Map[K, V]] performed by method any2stringadd in scala.Predef.
This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:
`(map: any2stringadd[Map[K, V]]).+(other)`
Definition Classes
2. def filter(p: ((K, V)) ⇒ Boolean): TraversableOnce[(K, V)]
Implicit
This member is added by an implicit conversion from Map[K, V] to MonadOps[(K, V)] performed by method MonadOps in scala.collection.TraversableOnce.
This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:
`(map: MonadOps[(K, V)]).filter(p)`
Definition Classes
3. def flatMap[B](f: ((K, V)) ⇒ GenTraversableOnce[B]): TraversableOnce[B]
Implicit
This member is added by an implicit conversion from Map[K, V] to MonadOps[(K, V)] performed by method MonadOps in scala.collection.TraversableOnce.
This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:
`(map: MonadOps[(K, V)]).flatMap(f)`
Definition Classes
4. def map[B](f: ((K, V)) ⇒ B): TraversableOnce[B]
Implicit
This member is added by an implicit conversion from Map[K, V] to MonadOps[(K, V)] performed by method MonadOps in scala.collection.TraversableOnce.
This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:
`(map: MonadOps[(K, V)]).map(f)`
Definition Classes
5. def withFilter(p: ((K, V)) ⇒ Boolean): Iterator[(K, V)]
Implicit
This member is added by an implicit conversion from Map[K, V] to MonadOps[(K, V)] performed by method MonadOps in scala.collection.TraversableOnce.
This implicitly inherited member is shadowed by one or more members in this class.
To access this member you can use a type ascription:
`(map: MonadOps[(K, V)]).withFilter(p)`
Definition Classes

### Deprecated Value Members

1. def /:[B](z: B)(op: (B, (K, V)) ⇒ B): B

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

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

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

Examples:

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

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

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

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

Note: will not terminate for infinite-sized collections.

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

B

the result type of the binary operator.

z

the start value.

op

the binary operator.

returns

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

`op(...op(op(z, x_1), x_2), ..., x_n)`

where `x1, ..., xn` are the elements of this traversable or iterator.

Definition Classes
TraversableOnceGenTraversableOnce
Annotations
Deprecated

(Since version 2.12.10) Use foldLeft instead of /:

2. def :\[B](z: B)(op: ((K, V), B) ⇒ B): B

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

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

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

Note: will not terminate for infinite-sized collections.

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

Examples:

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

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

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

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

the result type of the binary operator.

z

the start value

op

the binary operator

returns

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

`op(x_1, op(x_2, ... op(x_n, z)...))`

where `x1, ..., xn` are the elements of this traversable or iterator.

Definition Classes
TraversableOnceGenTraversableOnce
Annotations
Deprecated

(Since version 2.12.10) Use foldRight instead of :\

3. def formatted(fmtstr: String)

Returns string formatted according to given `format` string.

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

Implicit
This member is added by an implicit conversion from Map[K, V] to StringFormat[Map[K, V]] performed by method StringFormat in scala.Predef.
Definition Classes
StringFormat
Annotations
()
Deprecated

(Since version 2.12.16) Use `formatString.format(value)` instead of `value.formatted(formatString)`, or use the `f""` string interpolator. In Java 15 and later, `formatted` resolves to the new method in String which has reversed parameters.