# Map

#### trait Map[A, +B] extends Iterable[(A, B)] with Map[A, B] with MapLike[A, B, Map[A, B]]

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

```   def get(key: A): Option[B]
def iterator: Iterator[(A, B)]
def + [B1 >: B](kv: (A, B1)): Map[A, B1]
def -(key: A): Map[A, B]
```
Self Type
Map[A, B]
Source
Map.scala
Since

1

Linear Supertypes
MapLike[A, B, Map[A, B]], Map[A, B], MapLike[A, B, Map[A, B]], Subtractable[A, Map[A, B]], PartialFunction[A, B], (A) ⇒ B, GenMap[A, B], GenMapLike[A, B, Map[A, B]], Iterable[(A, B)], Iterable[(A, B)], IterableLike[(A, B), Map[A, B]], Equals, GenIterable[(A, B)], GenIterableLike[(A, B), Map[A, B]], Traversable[(A, B)], Immutable, Traversable[(A, B)], GenTraversable[(A, B)], GenericTraversableTemplate[(A, B), Iterable], TraversableLike[(A, B), Map[A, B]], GenTraversableLike[(A, B), Map[A, B]], Parallelizable[(A, B), ParMap[A, B]], TraversableOnce[(A, B)], GenTraversableOnce[(A, B)], FilterMonadic[(A, B), Map[A, B]], HasNewBuilder[(A, B), Map[A, B]], AnyRef, Any
Known Subclasses
Ordering
1. Alphabetic
2. By inheritance
Inherited
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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
Visibility
1. Public
2. All

### Type Members

1. #### class DefaultKeySet extends AbstractSet[A] with Set[A]

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

2. #### class DefaultValuesIterable extends AbstractIterable[B] with Iterable[B]

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

Attributes
protected
4. #### type Self = Map[A, B]

The type implementing this traversable

The type implementing this traversable

Attributes
protected
Definition Classes
TraversableLike
5. #### class WithFilter extends FilterMonadic[A, Repr]

A class supporting filtered operations.

### Abstract Value Members

1. #### abstract def +[B1 >: B](kv: (A, B1)): Map[A, B1]

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

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

B1

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: A): Option[B]

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[(A, B)]

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: AnyRef): Boolean

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

Test two objects for inequality.

Test two objects for inequality.

returns

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

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

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

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

returns

a hash value consistent with ==

Definition Classes
AnyRef → Any
4. #### def +[B1 >: B](elem1: (A, B1), elem2: (A, B1), elems: (A, B1)*): Map[A, B1]

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.

B1

the type of the added values

elem1

elem2

elems

returns

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

Definition Classes
MapLikeMapLike
5. #### def ++[B1 >: B](xs: GenTraversableOnce[(A, B1)]): Map[A, B1]

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.

B1

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
6. #### def ++[B](that: GenTraversableOnce[B]): immutable.Map[B]

[use case]

[use case]
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
TraversableLikeGenTraversableLike
7. #### def ++:[B >: (A, B), That](that: Traversable[B])(implicit bf: CanBuildFrom[Map[A, B], 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 and the new element type `B`.

returns

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

Definition Classes
TraversableLike
8. #### def ++:[B](that: TraversableOnce[B]): immutable.Map[B]

[use case]

[use case]
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
9. #### def -(elem1: A, elem2: A, elems: A*): Map[A, B]

Creates a new immutable map from this immutable map with some elements removed.

Creates a new immutable map from this immutable map 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 immutable map that contains all elements of the current immutable map except one less occurrence of each of the given elements.

Definition Classes
Subtractable
10. #### abstract def -(key: A): Map[A, B]

[use case]

[use case]
key

the key to be removed

returns

a new map without a binding for `key`

Definition Classes
MapLikeSubtractableGenMapLike
11. #### def --(xs: GenTraversableOnce[A]): Map[A, B]

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

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

returns

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

Definition Classes
Subtractable
12. #### def /:[B](z: B)(op: (B, (A, B)) ⇒ B): B

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

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

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

Examples:

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

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

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

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

Note: 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 immutable map, going left to right with the start value `z` on the left:

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

where `x1, ..., xn` are the elements of this immutable map.

Definition Classes
TraversableOnceGenTraversableOnce
13. #### def /:\[A1 >: (A, B)](z: A1)(op: (A1, A1) ⇒ A1): A1

A syntactic sugar for out of order folding.

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

Example:

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

scala> val b = (a /:\ 5)(_+_)
b: Int = 15
```
Definition Classes
GenTraversableOnce
14. #### def :\[B](z: B)(op: ((A, B), B) ⇒ B): B

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

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

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

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

Examples:

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

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

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

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

```
B

the result type of the binary operator.

z

the start value

op

the binary operator

returns

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

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

where `x1, ..., xn` are the elements of this immutable map.

Definition Classes
TraversableOnceGenTraversableOnce
15. #### final def ==(arg0: AnyRef): Boolean

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

Test two objects for equality.

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

returns

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

Definition Classes
Any
17. #### def addString(b: StringBuilder, start: String, sep: String, end: String): StringBuilder

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
18. #### def addString(b: StringBuilder): StringBuilder

Appends all elements of this immutable map to a string builder.

Appends all elements of this immutable map to a string builder. The written text consists of the string representations (w.r.t. the method `toString`) of all elements of this immutable map without any separator string.

Example:

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

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

b: StringBuilder = 1234
```
b

the string builder to which elements are appended.

returns

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

Definition Classes
TraversableOnce
19. #### def addString(b: StringBuilder, sep: String): StringBuilder

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

Appends all elements of this immutable map 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 immutable map, separated by the string `sep`.

Example:

```     scala> val a = LinkedList(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
20. #### def aggregate[B](z: B)(seqop: (B, (A, B)) ⇒ B, combop: (B, B) ⇒ B): B

Aggregates the results of applying an operator to subsequent elements.

Aggregates the results of applying an operator to subsequent elements.

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

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

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

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

B

the type of accumulated results

z

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

seqop

an operator used to accumulate results within a partition

combop

an associative operator used to combine results from different partitions

Definition Classes
TraversableOnceGenTraversableOnce
21. #### def andThen[C](k: (B) ⇒ C): PartialFunction[A, 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
22. #### def apply(key: A): B

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
23. #### 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`.

24. #### def canEqual(that: Any): Boolean

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 immutable map should be compared

returns

`true`, if this immutable map 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
25. #### def clone(): AnyRef

Create a copy of the receiver object.

Create a copy of the receiver object.

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

returns

a copy of the receiver object.

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

not specified by SLS as a member of AnyRef

26. #### def collect[B](pf: PartialFunction[(A, B), B]): immutable.Map[B]

[use case]

[use case]
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
27. #### def collectFirst[B](pf: PartialFunction[(A, B), B]): Option[B]

Finds the first element of the immutable map for which the given partial function is defined, and applies the partial function to it.

Finds the first element of the immutable map for which the given partial function is defined, and applies the partial function to it.

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)`

28. #### def companion: GenericCompanion[Iterable]

The factory companion object that builds instances of class immutable.

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

Definition Classes
IterableIterableGenIterableTraversableTraversableGenTraversableGenericTraversableTemplate
29. #### def compose[A](g: (A) ⇒ A): (A) ⇒ B

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
30. #### def contains(key: A): Boolean

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
31. #### def copyToArray(xs: Array[(A, B)], start: Int, len: Int): Unit

[use case]

[use case]
xs

the array to fill.

start

the starting index.

len

the maximal number of elements to copy.

Definition Classes
IterableLikeTraversableLikeTraversableOnceGenTraversableOnce
32. #### def copyToArray(xs: Array[(A, B)]): Unit

[use case]

[use case]
xs

the array to fill.

Definition Classes
TraversableOnceGenTraversableOnce
33. #### def copyToArray(xs: Array[(A, B)], start: Int): Unit

[use case]

[use case]
xs

the array to fill.

start

the starting index.

Definition Classes
TraversableOnceGenTraversableOnce
34. #### def copyToBuffer[B >: (A, B)](dest: Buffer[B]): Unit

Copies all elements of this immutable map to a buffer.

Copies all elements of this immutable map to a buffer.

dest

The buffer to which elements are copied.

Definition Classes
TraversableOnce
35. #### def count(p: ((A, B)) ⇒ Boolean): Int

Counts the number of elements in the immutable map which satisfy a predicate.

Counts the number of elements in the immutable map which satisfy a predicate.

p

the predicate used to test elements.

returns

the number of elements satisfying the predicate `p`.

Definition Classes
TraversableOnceGenTraversableOnce
36. #### def default(key: A): B

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
`NoSuchElementException`

37. #### def drop(n: Int): Map[A, B]

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 immutable map.

returns

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

Definition Classes
IterableLikeTraversableLikeGenTraversableLike
38. #### def dropRight(n: Int): Map[A, B]

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 immutable map consisting of all elements of this immutable map except the last `n` ones, or else the empty immutable map, if this immutable map has less than `n` elements.

Definition Classes
IterableLike
39. #### def dropWhile(p: ((A, B)) ⇒ Boolean): Map[A, B]

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.

p

The predicate used to test elements.

returns

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

Definition Classes
TraversableLikeGenTraversableLike
40. #### def empty: Map[A, B]

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
41. #### final def eq(arg0: AnyRef): Boolean

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

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

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

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

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

returns

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

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

Compares two maps structurally; i.

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
43. #### def exists(p: ((A, B)) ⇒ Boolean): Boolean

Tests whether a predicate holds for some of the elements of this immutable map.

Tests whether a predicate holds for some of the elements of this immutable map.

p

the predicate used to test elements.

returns

`true` if the given predicate `p` holds for some of the elements of this immutable map, otherwise `false`.

Definition Classes
IterableLikeTraversableLikeTraversableOnceGenTraversableOnce
44. #### def filter(p: ((A, B)) ⇒ Boolean): Map[A, B]

Selects all elements of this immutable map which satisfy a predicate.

Selects all elements of this immutable map which satisfy a predicate.

p

the predicate used to test elements.

returns

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

Definition Classes
TraversableLikeGenTraversableLike
45. #### def filterKeys(p: (A) ⇒ Boolean): Map[A, B]

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
46. #### def filterNot(p: ((A, B)) ⇒ Boolean): Map[A, B]

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

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

Note: This method works by successively removing elements fro which the predicate is false 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
47. #### def finalize(): Unit

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

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

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

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

not specified by SLS as a member of AnyRef

48. #### def find(p: ((A, B)) ⇒ Boolean): Option[(A, B)]

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

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

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 immutable map that satisfies `p`, or `None` if none exists.

Definition Classes
IterableLikeTraversableLikeTraversableOnceGenTraversableOnce
49. #### def flatMap[B](f: ((A, B)) ⇒ GenTraversableOnce[B]): immutable.Map[B]

[use case]

[use case]
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
50. #### def fold[A1 >: (A, B)](z: A1)(op: (A1, A1) ⇒ A1): A1

Folds the elements of this immutable map using the specified associative binary operator.

Folds the elements of this immutable map using the specified associative binary operator.

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

A1

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

z

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

op

a binary operator that must be associative

returns

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

Definition Classes
TraversableOnceGenTraversableOnce
51. #### def foldLeft[B](z: B)(op: (B, (A, B)) ⇒ B): B

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

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

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 immutable map, going left to right with the start value `z` on the left:

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

where `x1, ..., xn` are the elements of this immutable map.

Definition Classes
TraversableOnceGenTraversableOnce
52. #### def foldRight[B](z: B)(op: ((A, B), B) ⇒ B): B

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

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

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 immutable map, going right to left with the start value `z` on the right:

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

where `x1, ..., xn` are the elements of this immutable map.

Definition Classes
IterableLikeTraversableOnceGenTraversableOnce
53. #### def forall(p: ((A, B)) ⇒ Boolean): Boolean

Tests whether a predicate holds for all elements of this immutable map.

Tests whether a predicate holds for all elements of this immutable map.

p

the predicate used to test elements.

returns

`true` if the given predicate `p` holds for all elements of this immutable map, otherwise `false`.

Definition Classes
IterableLikeTraversableLikeTraversableOnceGenTraversableOnce
54. #### def foreach(f: ((A, B)) ⇒ Unit): Unit

[use case]

[use case]
f

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

Definition Classes
55. #### def genericBuilder[B]: Builder[B, Iterable[B]]

The generic builder that builds instances of immutable.

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

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

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

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

The nature of the representation is platform dependent.

returns

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

Definition Classes
AnyRef → Any
Note

not specified by SLS as a member of AnyRef

57. #### def getOrElse(key: A, default: ⇒ B): B

[use case]

[use case]
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
58. #### def groupBy[K](f: ((A, B)) ⇒ K): Map[K, Map[A, B]]

Partitions this immutable map into a map of immutable maps according to some discriminator function.

Partitions this immutable map into a map of immutable maps 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 immutable map.

K

the type of keys returned by the discriminator function.

f

the discriminator function.

returns

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

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

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

Definition Classes
TraversableLikeGenTraversableLike
59. #### def grouped(size: Int): Iterator[Map[A, B]]

Partitions elements in fixed size immutable maps.

Partitions elements in fixed size immutable maps.

size

the number of elements per group

returns

An iterator producing immutable maps of size `size`, except the last will be truncated if the elements don't divide evenly.

Definition Classes
IterableLike

Iterator#grouped

60. #### def hasDefiniteSize: Boolean

Tests whether this immutable map is known to have a finite size.

Tests whether this immutable map 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.

Note: many collection methods will not work on collections of infinite sizes.

returns

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

Definition Classes
TraversableLikeTraversableOnceGenTraversableOnce
61. #### def hashCode(): Int

The hashCode method for reference types.

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

returns

the hash code value for this object.

Definition Classes
GenMapLike → AnyRef → Any
62. #### def head: (A, B)

Selects the first element of this immutable map.

Selects the first element of this immutable map.

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

returns

the first element of this immutable map.

Definition Classes
IterableLikeGenIterableLikeTraversableLikeGenTraversableLike
Exceptions thrown
`NoSuchElementException`

if the immutable map is empty.

63. #### def headOption: Option[(A, B)]

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 immutable map if it is nonempty, `None` if it is empty.

Definition Classes
TraversableLike
64. #### def init: Map[A, B]

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 immutable map consisting of all elements of this immutable map except the last one.

Definition Classes
TraversableLike
Exceptions thrown
`UnsupportedOperationException`

if the immutable map is empty.

65. #### def inits: Iterator[Map[A, B]]

Iterates over the inits of this immutable map.

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

returns

an iterator over all the inits of this immutable map

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

66. #### def isDefinedAt(key: A): Boolean

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
67. #### def isEmpty: Boolean

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
MapLikeIterableLikeGenIterableLikeTraversableLikeTraversableOnceGenTraversableOnce
68. #### final def isInstanceOf[T0]: Boolean

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

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

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

returns

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

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

Tests whether this immutable map can be repeatedly traversed.

Tests whether this immutable map can be repeatedly traversed.

returns

`true`

Definition Classes
GenTraversableLikeGenTraversableOnce
70. #### def keySet: Set[A]

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
71. #### def keys: Iterable[A]

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[A]` rather than `Iterator[A]`.

72. #### def keysIterator: Iterator[A]

Creates an iterator for all keys.

Creates an iterator for all keys.

returns

an iterator over all keys.

Definition Classes
MapLikeGenMapLike
73. #### def last: (A, B)

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 immutable map.

Definition Classes
TraversableLike
Exceptions thrown
NoSuchElementException

If the immutable map is empty.

74. #### def lastOption: Option[(A, B)]

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 immutable map\$ if it is nonempty, `None` if it is empty.

Definition Classes
TraversableLike
75. #### def lift: (A) ⇒ Option[B]

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

Turns this partial function into an 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

76. #### def map[B](f: ((A, B)) ⇒ B): immutable.Map[B]

[use case]

[use case]
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
77. #### def mapValues[C](f: (B) ⇒ C): Map[A, C]

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
78. #### def max: A

[use case]

[use case]
returns

the largest element of this immutable map.

Definition Classes
TraversableOnceGenTraversableOnce
79. #### def maxBy[B](f: ((A, B)) ⇒ B)(implicit cmp: Ordering[B]): (A, B)

Definition Classes
TraversableOnceGenTraversableOnce
80. #### def min: A

[use case]

[use case]
returns

the smallest element of this immutable map

Definition Classes
TraversableOnceGenTraversableOnce
81. #### def minBy[B](f: ((A, B)) ⇒ B)(implicit cmp: Ordering[B]): (A, B)

Definition Classes
TraversableOnceGenTraversableOnce
82. #### def missingCase(x: A): B

Attributes
protected
Definition Classes
PartialFunction
83. #### def mkString: String

Displays all elements of this immutable map in a string.

Displays all elements of this immutable map in a string.

returns

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

Definition Classes
TraversableOnceGenTraversableOnce
84. #### def mkString(sep: String): String

Displays all elements of this immutable map in a string using a separator string.

Displays all elements of this immutable map in a string using a separator string.

sep

the separator string.

returns

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

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

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

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

Displays all elements of this immutable map 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 immutable map. 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 immutable map are separated by the string `sep`.

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

86. #### final def ne(arg0: AnyRef): Boolean

Equivalent to `!(this eq that)`.

Equivalent to `!(this eq that)`.

returns

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

Definition Classes
AnyRef
87. #### def newBuilder: Builder[(A, B), Map[A, B]]

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
88. #### def nonEmpty: Boolean

Tests whether the immutable map is not empty.

Tests whether the immutable map is not empty.

returns

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

Definition Classes
TraversableOnceGenTraversableOnce
89. #### final def notify(): Unit

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

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

Definition Classes
AnyRef
Note

not specified by SLS as a member of AnyRef

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

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

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

Definition Classes
AnyRef
Note

not specified by SLS as a member of AnyRef

91. #### def orElse[A1 <: A, B1 >: B](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
92. #### def orElseFast[A1 <: A, B1 >: B](that: PartialFunction[A1, B1]): PartialFunction[A1, B1]

Definition Classes
PartialFunction
93. #### def par: ParMap[A, B]

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[(A, B), ParMap[A, B]]

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: ((A, B)) ⇒ Boolean): (Map[A, B], Map[A, B])

Partitions this immutable map in two immutable maps according to a predicate.

Partitions this immutable map in two immutable maps according to a predicate.

p

the predicate on which to partition.

returns

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

Definition Classes
TraversableLikeGenTraversableLike
96. #### def product: A

[use case]

[use case]
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
97. #### def reduce[A1 >: (A, B)](op: (A1, A1) ⇒ A1): A1

Reduces the elements of this immutable map using the specified associative binary operator.

Reduces the elements of this immutable map 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 immutable map is nonempty.

Definition Classes
TraversableOnceGenTraversableOnce
Exceptions thrown
UnsupportedOperationException

if this immutable map is empty.

98. #### def reduceLeft[B >: (A, B)](op: (B, (A, B)) ⇒ B): B

Definition Classes
TraversableOnce
99. #### def reduceLeftOption[B >: (A, B)](op: (B, (A, B)) ⇒ B): Option[B]

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

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

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

B

the result type of the binary operator.

op

the binary operator.

returns

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

Definition Classes
TraversableOnceGenTraversableOnce
100. #### def reduceOption[A1 >: (A, B)](op: (A1, A1) ⇒ A1): Option[A1]

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

Reduces the elements of this immutable map, 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 >: (A, B)](op: ((A, B), B) ⇒ B): B

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

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

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 immutable map, going right to left:

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

where `x1, ..., xn` are the elements of this immutable map.

Definition Classes
IterableLikeTraversableOnceGenTraversableOnce
Exceptions thrown
`UnsupportedOperationException`

if this immutable map is empty.

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

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

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

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

B

the result type of the binary operator.

op

the binary operator.

returns

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

Definition Classes
TraversableOnceGenTraversableOnce
103. #### def repr: Map[A, B]

The collection of type immutable map underlying this `TraversableLike` object.

The collection of type immutable map 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: List[(A, B)]

Attributes
protected[this]
Definition Classes
TraversableOnce
105. #### def sameElements(that: GenIterable[(A, B)]): Boolean

[use case]

[use case]
that

the collection to compare with.

returns

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

Definition Classes
IterableLikeGenIterableLike
106. #### def scan[B >: (A, B), That](z: B)(op: (B, B) ⇒ B)(implicit cbf: CanBuildFrom[Map[A, B], 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 immutable map containing the prefix scan of the elements in this immutable map

Definition Classes
TraversableLikeGenTraversableLike
107. #### def scanLeft[B, That](z: B)(op: (B, (A, B)) ⇒ B)(implicit bf: CanBuildFrom[Map[A, B], B, That]): That

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

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

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

B

the type of the elements in the resulting collection

That

the actual type of the resulting collection

z

the initial value

op

the binary operator applied to the intermediate result and the element

bf

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

returns

collection with intermediate results

Definition Classes
TraversableLikeGenTraversableLike
108. #### def scanRight[B, That](z: B)(op: ((A, B), B) ⇒ B)(implicit bf: CanBuildFrom[Map[A, B], B, That]): That

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

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

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

Example:

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

the type of the elements in the resulting collection

That

the actual type of the resulting collection

z

the initial value

op

the binary operator applied to the intermediate result and the element

bf

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

returns

collection with intermediate results

Definition Classes
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.

109. #### def seq: Map[A, B]

A version of this collection with all of the operations implemented sequentially (i.

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
110. #### def size: Int

The size of this immutable map.

The size of this immutable map.

returns

the number of elements in this immutable map.

Definition Classes
TraversableOnceGenTraversableOnce
111. #### def slice(from: Int, until: Int): Map[A, B]

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.

from

the lowest index to include from this immutable map.

until

the highest index to EXCLUDE from this immutable map.

returns

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

Definition Classes
IterableLikeTraversableLikeGenTraversableLike
112. #### def sliding(size: Int, step: Int): Iterator[Map[A, B]]

Definition Classes
IterableLike
113. #### def sliding(size: Int): Iterator[Map[A, B]]

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

returns

An iterator producing immutable maps of size `size`, except the last and the only element will be truncated if there are fewer elements than size.

Definition Classes
IterableLike

Iterator#sliding

114. #### def span(p: ((A, B)) ⇒ Boolean): (Map[A, B], Map[A, B])

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

Splits this immutable map 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.

p

the test predicate

returns

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

Definition Classes
TraversableLikeGenTraversableLike
115. #### def splitAt(n: Int): (Map[A, B], Map[A, B])

Splits this immutable map into two at a given position.

Splits this immutable map 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 immutable maps consisting of the first `n` elements of this immutable map, and the other elements.

Definition Classes
TraversableLikeGenTraversableLike
116. #### def stringPrefix: String

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

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

returns

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

Definition Classes
MapLikeTraversableLikeGenTraversableLike
117. #### def sum: A

[use case]

[use case]
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
118. #### final def synchronized[T0](arg0: ⇒ T0): T0

Definition Classes
AnyRef
119. #### def tail: Map[A, B]

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 immutable map consisting of all elements of this immutable map except the first one.

Definition Classes
TraversableLikeGenTraversableLike
Exceptions thrown
`UnsupportedOperationException`

if the immutable map is empty.

120. #### def tails: Iterator[Map[A, B]]

Iterates over the tails of this immutable map.

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

returns

an iterator over all the tails of this immutable map

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

121. #### def take(n: Int): Map[A, B]

Selects first n elements.

Selects first n elements.

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

n

Tt number of elements to take from this immutable map.

returns

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

Definition Classes
IterableLikeTraversableLikeGenTraversableLike
122. #### def takeRight(n: Int): Map[A, B]

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 immutable map consisting only of the last `n` elements of this immutable map, or else the whole immutable map, if it has less than `n` elements.

Definition Classes
IterableLike
123. #### def takeWhile(p: ((A, B)) ⇒ Boolean): Map[A, B]

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.

p

The predicate used to test elements.

returns

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

Definition Classes
IterableLikeTraversableLikeGenTraversableLike
124. #### def thisCollection: Iterable[(A, B)]

The underlying collection seen as an instance of `immutable.Map`.

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

Attributes
protected[this]
Definition Classes
IterableLikeTraversableLike
125. #### def toArray: Array[A]

[use case]

[use case]
returns

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

Definition Classes
TraversableOnceGenTraversableOnce
126. #### def toBuffer[C >: (A, B)]: Buffer[C]

Converts this immutable map to a mutable buffer.

Converts this immutable map to a mutable buffer.

returns

a buffer containing all elements of this immutable map.

Definition Classes
MapLikeTraversableOnceGenTraversableOnce
127. #### def toCollection(repr: Map[A, B]): Iterable[(A, B)]

A conversion from collections of type `Repr` to `immutable.Map` objects.

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

Attributes
protected[this]
Definition Classes
IterableLikeTraversableLike
128. #### def toIndexedSeq: IndexedSeq[(A, B)]

Converts this immutable map to an indexed sequence.

Converts this immutable map to an indexed sequence.

returns

an indexed sequence containing all elements of this immutable map.

Definition Classes
TraversableOnceGenTraversableOnce
129. #### def toIterable: Iterable[(A, B)]

Converts this immutable map to an iterable collection.

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

returns

an `Iterable` containing all elements of this immutable map.

Definition Classes
IterableLikeTraversableOnceGenTraversableOnce
130. #### def toIterator: Iterator[(A, B)]

Returns an Iterator over the elements in this immutable map.

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

returns

an Iterator containing all elements of this immutable map.

Definition Classes
IterableLikeTraversableLikeGenTraversableOnce
131. #### def toList: List[(A, B)]

Converts this immutable map to a list.

Converts this immutable map to a list.

returns

a list containing all elements of this immutable map.

Definition Classes
TraversableOnceGenTraversableOnce
132. #### def toMap[T, U]: Map[T, U]

[use case]

[use case]
returns

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

Definition Classes
MapTraversableOnceGenTraversableOnce
133. #### def toSeq: Seq[(A, B)]

Overridden for efficiency.

Overridden for efficiency.

returns

a sequence containing all elements of this immutable map.

Definition Classes
MapLikeTraversableOnceGenTraversableOnce
134. #### def toSet[B >: (A, B)]: Set[B]

Converts this immutable map to a set.

Converts this immutable map to a set.

returns

a set containing all elements of this immutable map.

Definition Classes
TraversableOnceGenTraversableOnce
135. #### def toStream: Stream[(A, B)]

Converts this immutable map to a stream.

Converts this immutable map to a stream.

returns

a stream containing all elements of this immutable map.

Definition Classes
IterableLikeTraversableLikeGenTraversableOnce
136. #### def toString(): String

Converts this immutable map to a string.

Converts this immutable map to a string.

returns

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

Definition Classes
MapLikeTraversableLikeFunction1 → AnyRef → Any
137. #### def toTraversable: Traversable[(A, B)]

Converts this immutable map to an unspecified Traversable.

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

returns

a Traversable containing all elements of this immutable map.

Definition Classes
TraversableLikeTraversableOnceGenTraversableOnce
138. #### def transform[C, That](f: (A, B) ⇒ C)(implicit bf: CanBuildFrom[Map[A, B], (A, C), 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
139. #### def unzip[A1, A2](implicit asPair: ((A, B)) ⇒ (A1, A2)): (Iterable[A1], Iterable[A2])

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

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

asPair

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

returns

a pair immutable maps, containing the first, respectively second half of each element pair of this immutable map.

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

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

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

asTriple

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

returns

a triple immutable maps, containing the first, second, respectively third member of each element triple of this immutable map.

Definition Classes
GenericTraversableTemplate
141. #### def updated[B1 >: B](key: A, value: B1): Map[A, B1]

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

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

B1

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
142. #### def values: Iterable[B]

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[B]` rather than `Iterator[B]`.

143. #### def valuesIterator: Iterator[B]

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
144. #### def view(from: Int, until: Int): IterableView[(A, B), Map[A, B]]

Creates a non-strict view of a slice of this immutable map.

Creates a non-strict view of a slice of this immutable map.

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

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 immutable map, starting at index `from` and extending up to (but not including) index `until`.

Definition Classes
IterableLikeTraversableLike
145. #### def view: IterableView[(A, B), Map[A, B]]

Creates a non-strict view of this immutable map.

Creates a non-strict view of this immutable map.

returns

a non-strict view of this immutable map.

Definition Classes
IterableLikeTraversableLike
146. #### final def wait(): Unit

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

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

Definition Classes
AnyRef
Annotations
()
149. #### def withDefault[B1 >: B](d: (A) ⇒ B1): Map[A, B1]

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

150. #### def withDefaultValue[B1 >: B](d: B1): Map[A, B1]

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

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

returns

a wrapper of the map with a default value

151. #### def withFilter(p: ((A, B)) ⇒ Boolean): FilterMonadic[(A, B), Map[A, B]]

Creates a non-strict filter of this immutable map.

Creates a non-strict filter of this immutable map.

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 immutable map which satisfy the predicate `p`.

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

[use case]

[use case]
B

the type of the second half of the returned pairs

that

The iterable providing the second half of each result pair

returns

a new 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
153. #### def zipAll[B](that: Iterable[B], thisElem: (A, B), thatElem: B): immutable.Map[(A, B)]

[use case]

[use case]
B

the type of the second half of the returned pairs

that

The iterable providing the second half of each result pair

thisElem

the element to be used to fill up the result if this 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
154. #### def zipWithIndex: immutable.Map[(A, Int)]

[use case]

[use case]
returns

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

Definition Classes
IterableLikeGenIterableLike