MapValues
Attributes
- Source
- MapView.scala
- Graph
- Supertypes
Members list
Value members
Concrete methods
Optionally returns the value associated with a key.
Optionally returns the value associated with a key.
Value parameters
- key
the key value
Attributes
- Returns
an option value containing the value associated with
keyin this map, orNoneif none exists.- Source
- MapView.scala
Tests whether the map is empty.
Tests whether the map is empty.
Note: The default implementation creates and discards an iterator.
Note: Implementations in subclasses that are not repeatedly iterable must take care not to consume any elements whenisEmpty is called.
Attributes
- Returns
trueif the map contains no elements,falseotherwise.- Definition Classes
- Source
- MapView.scala
Anscala.collection.Iterator over the elements of this map.
Anscala.collection.Iterator over the elements of this map.
If anIterableOnce object is in fact anscala.collection.Iterator, this method always returns itself, in its current state, but if it is anscala.collection.Iterable, this method always returns a newscala.collection.Iterator.
Attributes
- Source
- MapView.scala
The number of elements in this map, if it can be cheaply computed, -1 otherwise.
The number of elements in this map, if it can be cheaply computed, -1 otherwise. Cheaply usually means: Not requiring a collection traversal.
Attributes
- Definition Classes
- Source
- MapView.scala
Inherited methods
Alias forconcat
Appends all elements of this collection to a string builder.
Appends all elements of this collection to a string builder. The written text consists of the string representations (w.r.t. the methodtoString) of all elements of this collection without any separator string.
Example:
scala> val a = List(1,2,3,4)a: List[Int] = List(1, 2, 3, 4)scala> val b = new StringBuilder()b: StringBuilder =scala> val h = a.addString(b)h: StringBuilder = 1234Value parameters
- b
the string builder to which elements are appended.
Attributes
- Returns
the string builder
bto which elements were appended.- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Appends all elements of this collection to a string builder using a separator string.
Appends all elements of this collection to a string builder using a separator string. The written text consists of the string representations (w.r.t. the methodtoString) of all elements of this collection, separated by the stringsep.
Example:
scala> val a = List(1,2,3,4)a: List[Int] = List(1, 2, 3, 4)scala> val b = new StringBuilder()b: StringBuilder =scala> a.addString(b, ", ")res0: StringBuilder = 1, 2, 3, 4Value parameters
- b
the string builder to which elements are appended.
- sep
the separator string.
Attributes
- Returns
the string builder
bto which elements were appended.- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Appends all elements of this map to a string builder using start, end, and separator strings.
Appends all elements of this map to a string builder using start, end, and separator strings. The written text begins with the stringstart and ends with the stringend. Inside, the string representations (w.r.t. the methodtoString) of all elements of this map are separated by the stringsep.
Example:
scala> val a = List(1,2,3,4)a: List[Int] = List(1, 2, 3, 4)scala> val b = new StringBuilder()b: StringBuilder =scala> a.addString(b , "List(" , ", " , ")")res5: StringBuilder = List(1, 2, 3, 4)Value parameters
- b
the string builder to which elements are appended.
- end
the ending string.
- sep
the separator string.
- start
the starting string.
Attributes
Composes this partial function with another partial function that gets applied to results of this partial function.
Composes this partial function with another partial function that gets applied to results of this partial function.
Note that callingisDefinedAt on the resulting partial function may apply the first partial function and execute its side effect. For efficiency, it is recommended to callapplyOrElse instead ofisDefinedAt orapply.
Type parameters
- C
the result type of the transformation function.
Value parameters
- k
the transformation function
Attributes
- Returns
a partial function with the domain of this partial function narrowed by other partial function, which maps arguments
xtok(this(x)).- Inherited from:
- PartialFunction
- Source
- PartialFunction.scala
Composes this partial function with a transformation function that gets applied to results of this partial function.
Composes this partial function with a transformation function that gets applied to results of this partial function.
If the runtime type of the function is aPartialFunction then the otherandThen method is used (note its cautions).
Type parameters
- C
the result type of the transformation function.
Value parameters
- k
the transformation function
Attributes
- Returns
a partial function with the domain of this partial function, possibly narrowed by the specified function, which maps arguments
xtok(this(x)).- Definition Classes
- Inherited from:
- PartialFunction
- Source
- PartialFunction.scala
Retrieves the value which is associated with the given key.
Retrieves the value which is associated with the given key. This method invokes thedefault method of the map if there is no mapping from the given key to a value. Unless overridden, thedefault method throws aNoSuchElementException.
Value parameters
- key
the key
Attributes
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 expressionpf.applyOrElse(x, default) is equivalent to
if(pf isDefinedAt x) pf(x) else default(x)except thatapplyOrElse method can be implemented more efficiently. For all partial function literals the compiler generates anapplyOrElse implementation which avoids double evaluation of pattern matchers and guards. This makesapplyOrElse the basis for the efficient implementation for many operations and scenarios, such as:
- combining partial functions intoorElse/andThen chains does not lead to excessiveapply/isDefinedAt evaluation -lift andunlift 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 nontrivialisDefinedAt method it is recommended to overrideapplyOrElse with custom implementation that avoids doubleisDefinedAt evaluation. This may result in better performance and more predictable behavior w.r.t. side effects.
Value parameters
- default
the fallback function
- x
the function argument
Attributes
Builds a new iterable collection by applying a partial function to all elements of this iterable collection on which the function is defined.
Builds a new iterable collection by applying a partial function to all elements of this iterable collection on which the function is defined.
Type parameters
- B
the element type of the returned iterable collection.
Value parameters
- pf
the partial function which filters and maps the iterable collection.
Attributes
- Returns
a new iterable collection resulting from applying the given partial function
pfto each element on which it is defined and collecting the results. The order of the elements is preserved.- Inherited from:
- IterableOps
- Source
- Iterable.scala
Builds a new collection by applying a partial function to all elements of this map on which the function is defined.
Builds a new collection by applying a partial function to all elements of this map on which the function is defined.
Type parameters
- K2
the key type of the returned map.
- V2
the value type of the returned map.
Value parameters
- pf
the partial function which filters and maps the map.
Attributes
Finds the first element of the collection for which the given partial function is defined, and applies the partial function to it.
Finds the first element of the collection for which the given partial function is defined, and applies the partial function to it.
Note: may not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parameters
- pf
the partial function
Attributes
- Returns
an option value containing pf applied to the first value for which it is defined, or
Noneif none exists.- Example
Seq("a", 1, 5L).collectFirst({ case x: Int => x*10 }) = Some(10)- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Composes another partial functionk with this partial function so that this partial function gets applied to results ofk.
Composes another partial functionk with this partial function so that this partial function gets applied to results ofk.
Note that callingisDefinedAt on the resulting partial function may apply the first partial function and execute its side effect. For efficiency, it is recommended to callapplyOrElse instead ofisDefinedAt orapply.
Type parameters
- R
the parameter type of the transformation function.
Value parameters
- k
the transformation function
Attributes
- Returns
a partial function with the domain of other partial function narrowed by this partial function, which maps arguments
xtothis(k(x)).- Inherited from:
- PartialFunction
- Source
- PartialFunction.scala
Composes two instances ofFunction1 in a newFunction1, with this function applied last.
Composes two instances ofFunction1 in a newFunction1, with this function applied last.
Type parameters
- A
the type to which function
gcan be applied
Value parameters
- g
a function A => T1
Attributes
- Returns
a new function
fsuch thatf(x) == apply(g(x))- Inherited from:
- Function1
- Source
- Function1.scala
Returns a new iterable collection containing the elements from the left hand operand followed by the elements from the right hand operand.
Returns a new iterable collection containing the elements from the left hand operand followed by the elements from the right hand operand. The element type of the iterable collection is the most specific superclass encompassing the element types of the two operands.
Type parameters
- B
the element type of the returned collection.
Value parameters
- suffix
the iterable to append.
Attributes
- Returns
a new iterable collection which contains all elements of this iterable collection followed by all elements of
suffix.- Inherited from:
- IterableOps
- Source
- Iterable.scala
Returns a new map containing the elements from the left hand operand followed by the elements from the right hand operand.
Returns a new map containing the elements from the left hand operand followed by the elements from the right hand operand. The element type of the map is the most specific superclass encompassing the element types of the two operands.
Value parameters
- suffix
the iterable to append.
Attributes
Copy elements to an array, returning the number of elements written.
Copy elements to an array, returning the number of elements written.
Fills the given arrayxs starting at indexstart with at mostlen elements of this collection.
Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached, orlen elements have been copied.
Type parameters
- B
the type of the elements of the array.
Value parameters
- len
the maximal number of elements to copy.
- start
the starting index of xs.
- xs
the array to fill.
Attributes
- Returns
the number of elements written to the array
- Note
Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Copies elements to an array, returning the number of elements written.
Copies elements to an array, returning the number of elements written.
Fills the given arrayxs starting at indexstart with values of this collection.
Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached.
Type parameters
- B
the type of the elements of the array.
Value parameters
- start
the starting index of xs.
- xs
the array to fill.
Attributes
- Returns
the number of elements written to the array
- Note
Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Copies elements to an array, returning the number of elements written.
Copies elements to an array, returning the number of elements written.
Fills the given arrayxs starting at indexstart with values of this collection.
Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached.
Type parameters
- B
the type of the elements of the array.
Value parameters
- xs
the array to fill.
Attributes
- Returns
the number of elements written to the array
- Note
Reuse: After calling this method, one should discard the iterator it was called on. Using it is undefined and subject to change.
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Tests whether every element of this collection's iterator relates to the corresponding element of another collection by satisfying a test predicate.
Tests whether every element of this collection's iterator relates to the corresponding element of another collection by satisfying a test predicate.
Note: will not terminate for infinite-sized collections.
Type parameters
- B
the type of the elements of
that
Value parameters
- p
the test predicate, which relates elements from both collections
- that
the other collection
Attributes
- Returns
trueif both collections have the same length andp(x, y)istruefor all corresponding elementsxof this iterator andyofthat, otherwisefalse- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Counts the number of elements in the collection which satisfy a predicate.
Counts the number of elements in the collection which satisfy a predicate.
Note: will not terminate for infinite-sized collections.
Value parameters
- p
the predicate used to test elements.
Attributes
- Returns
the number of elements satisfying the predicate
p.- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Defines the default value computation for the map, returned when a key is not found.
Defines the default value computation for the map, returned when a key is not found.
The method implemented here throws an exception, but it may be overridden by subclasses.
Value parameters
- key
the given key value for which a binding is missing.
Attributes
- Throws
NoSuchElementException if no default value is defined
- Inherited from:
- MapOps
- Source
- Map.scala
Selects all elements except the firstn ones.
Selects all elements except the firstn ones.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parameters
- n
the number of elements to drop from this iterable collection.
Attributes
- Returns
a iterable collection consisting of all elements of this iterable collection except the first
nones, or else the empty iterable collection, if this iterable collection has less thannelements. Ifnis negative, don't drop any elements.- Inherited from:
- IterableOps
- Source
- Iterable.scala
Selects all elements except lastn ones.
Selects all elements except lastn ones.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parameters
- n
the number of elements to drop from this iterable collection.
Attributes
- Returns
a iterable collection consisting of all elements of this iterable collection except the last
nones, or else the empty iterable collection, if this iterable collection has less thannelements. Ifnis negative, don't drop any elements.- Inherited from:
- IterableOps
- Source
- Iterable.scala
Selects all elements except the longest prefix that satisfies a predicate.
Selects all elements except the longest prefix that satisfies a predicate.
The matching prefix starts with the first element of this iterable collection, and the element following the prefix is the first element that does not satisfy the predicate. The matching prefix may be empty, so that this method returns the entire iterable collection.
Example:
scala> List(1, 2, 3, 100, 4).dropWhile(n => n < 10)val res0: List[Int] = List(100, 4)scala> List(1, 2, 3, 100, 4).dropWhile(n => n == 0)val res1: List[Int] = List(1, 2, 3, 100, 4)Usespan to obtain both the prefix and suffix. UsefilterNot to drop all elements that satisfy the predicate.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parameters
- p
The predicate used to test elements.
Attributes
- Returns
the longest suffix of this iterable collection whose first element does not satisfy the predicate
p.- Inherited from:
- IterableOps
- Source
- Iterable.scala
Returns an extractor object with aunapplySeq method, which extracts each element of a sequence data.
Returns an extractor object with aunapplySeq method, which extracts each element of a sequence data.
Attributes
- Example
val firstChar: String => Option[Char] = _.headOptionSeq("foo", "bar", "baz") match { case firstChar.unlift.elementWise(c0, c1, c2) => println(s"$c0, $c1, $c2") // Output: f, b, b}- Inherited from:
- PartialFunction
- Source
- PartialFunction.scala
The empty iterable of the same type as this iterable
The empty iterable of the same type as this iterable
Attributes
- Returns
an empty iterable of type
C.- Definition Classes
- Inherited from:
- MapView
- Source
- MapView.scala
Tests whether a predicate holds for at least one element of this collection.
Tests whether a predicate holds for at least one element of this collection.
Note: may not terminate for infinite-sized collections.
Value parameters
- p
the predicate used to test elements.
Attributes
- Returns
trueif the given predicatepis satisfied by at least one element of this collection, otherwisefalse- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Selects all elements of this view which satisfy a predicate.
Selects all elements of this view which satisfy a predicate.
Value parameters
- p
the predicate used to test elements.
Attributes
- Returns
a new view consisting of all elements of this view that satisfy the given predicate
p. The order of the elements is preserved.- Definition Classes
- Inherited from:
- MapView
- Source
- MapView.scala
Filters this map by retaining only keys satisfying a predicate.
Filters this map by retaining only keys satisfying a predicate.
Value parameters
- p
the predicate used to test keys
Attributes
- 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
- Inherited from:
- MapView
- Source
- MapView.scala
Selects all elements of this view which do not satisfy a predicate.
Selects all elements of this view which do not satisfy a predicate.
Value parameters
- pred
the predicate used to test elements.
Attributes
- Returns
a new view consisting of all elements of this view that do not satisfy the given predicate
pred. Their order may not be preserved.- Definition Classes
- Inherited from:
- MapView
- Source
- MapView.scala
Finds the first element of the collection satisfying a predicate, if any.
Finds the first element of the collection satisfying a predicate, if any.
Note: may not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parameters
- p
the predicate used to test elements.
Attributes
- Returns
an option value containing the first element in the collection that satisfies
p, orNoneif none exists.- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Builds a new iterable collection by applying a function to all elements of this iterable collection and using the elements of the resulting collections.
Builds a new iterable collection by applying a function to all elements of this iterable collection and using the elements of the resulting collections.
For example:
def getWords(lines: Seq[String]): Seq[String] = lines flatMap (line => line split "\\W+")The type of the resulting collection is guided by the static type of iterable collection. This might cause unexpected results sometimes. For example:
// lettersOf will return a Seq[Char] of likely repeated letters, instead of a Setdef lettersOf(words: Seq[String]) = words flatMap (word => word.toSet)// lettersOf will return a Set[Char], not a Seqdef lettersOf(words: Seq[String]) = words.toSet flatMap ((word: String) => word.toSeq)// xs will be an Iterable[Int]val xs = Map("a" -> List(11,111), "b" -> List(22,222)).flatMap(_._2)// ys will be a Map[Int, Int]val ys = Map("a" -> List(1 -> 11,1 -> 111), "b" -> List(2 -> 22,2 -> 222)).flatMap(_._2)Type parameters
- B
the element type of the returned collection.
Value parameters
- f
the function to apply to each element.
Attributes
- Returns
a new iterable collection resulting from applying the given collection-valued function
fto each element of this iterable collection and concatenating the results.- Inherited from:
- IterableOps
- Source
- Iterable.scala
Builds a new map by applying a function to all elements of this map and using the elements of the resulting collections.
Builds a new map by applying a function to all elements of this map and using the elements of the resulting collections.
Value parameters
- f
the function to apply to each element.
Attributes
Converts this iterable collection of iterable collections into a iterable collection formed by the elements of these iterable collections.
Converts this iterable collection of iterable collections into a iterable collection formed by the elements of these iterable collections.
The resulting collection's type will be guided by the type of iterable collection. For example:
val xs = List( Set(1, 2, 3), Set(1, 2, 3) ).flatten// xs == List(1, 2, 3, 1, 2, 3)val ys = Set( List(1, 2, 3), List(3, 2, 1) ).flatten// ys == Set(1, 2, 3)Type parameters
- B
the type of the elements of each iterable collection.
Value parameters
- asIterable
an implicit conversion which asserts that the element type of this iterable collection is an
Iterable.
Attributes
- Returns
a new iterable collection resulting from concatenating all element iterable collections.
- Inherited from:
- IterableOps
- Source
- Iterable.scala
Applies the given binary operatorop to the given initial valuez and all elements of this collection.
Applies the given binary operatorop to the given initial valuez and all elements of this collection.
For each application of the operator, each operand is either an element of this collection, the initial value, or another such application of the operator.
The order of applications of the operator is unspecified and may be nondeterministic. Each element appears exactly once in the computation. The initial value may be used an arbitrary number of times, but at least once.
If this collection is ordered, then for any application of the operator, the element(s) appearing in the left operand will precede those in the right.
Note: might return different results for different runs, unless either of the following conditions is met: (1) the operator is associative, and the underlying collection type is ordered; or (2) the operator is associative and commutative. In either case, it is also necessary that the initial value be a neutral value for the operator, e.g.Nil forList concatenation or1 for multiplication.
The default implementation inIterableOnce is equivalent tofoldLeft but may be overridden for more efficient traversal orders.
Note: will not terminate for infinite-sized collections.
Type parameters
- A1
The type parameter for the binary operator, a supertype of
A.
Value parameters
- op
A binary operator; must be associative for the result to always be the same across runs.
- z
An initial value; may be used an arbitrary number of times in the computation of the result; must be a neutral value for
opfor the result to always be the same across runs.
Attributes
- Returns
The result of applying
opbetween all the elements andz, orzif this collection is empty.- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Applies the given binary operatorop to the given initial valuez and all elements of this collection, going left to right.
Applies the given binary operatorop to the given initial valuez and all elements of this collection, going left to right. Returns the initial value if this collection is empty.
"Going left to right" only makes sense if this collection is ordered: then ifx1,x2, ...,xn are the elements of this collection, the result isop( op( ... op( op(z, x1), x2) ... ), xn).
If this collection is not ordered, then for each application of the operator, each right operand is an element. In addition, the leftmost operand is the initial value, and each other left operand is itself an application of the operator. The elements of this collection and the initial value all appear exactly once in the computation.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Note: will not terminate for infinite-sized collections.
Type parameters
- B
The result type of the binary operator.
Value parameters
- op
A binary operator.
- z
An initial value.
Attributes
- Returns
The result of applying
optozand all elements of this collection, going left to right. Returnszif this collection is empty.- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Applies the given binary operatorop to all elements of this collection and the given initial valuez, going right to left.
Applies the given binary operatorop to all elements of this collection and the given initial valuez, going right to left. Returns the initial value if this collection is empty.
"Going right to left" only makes sense if this collection is ordered: then ifx1,x2, ...,xn are the elements of this collection, the result isop(x1, op(x2, op( ... op(xn, z) ... ))).
If this collection is not ordered, then for each application of the operator, each left operand is an element. In addition, the rightmost operand is the initial value, and each other right operand is itself an application of the operator. The elements of this collection and the initial value all appear exactly once in the computation.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Note: will not terminate for infinite-sized collections.
Type parameters
- B
The result type of the binary operator.
Value parameters
- op
A binary operator.
- z
An initial value.
Attributes
- Returns
The result of applying
opto all elements of this collection andz, going right to left. Returnszif this collection is empty.- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Tests whether a predicate holds for all elements of this collection.
Tests whether a predicate holds for all elements of this collection.
Note: may not terminate for infinite-sized collections.
Value parameters
- p
the predicate used to test elements.
Attributes
- Returns
trueif this collection is empty or the given predicatepholds for all elements of this collection, otherwisefalse.- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Appliesf to each element for its side effects.
Appliesf to each element for its side effects. Note:U parameter needed to help scalac's type inference.
Attributes
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Defines how to turn a givenIterable[A] into a collection of typeC.
Defines how to turn a givenIterable[A] into a collection of typeC.
This process can be done in a strict way or a non-strict way (ie. without evaluating the elements of the resulting collections). In other words, this methods defines the evaluation model of the collection.
Attributes
- Note
When implementing a custom collection type and refining
Cto the new type, this method needs to be overridden (the compiler will issue an error otherwise). In the common case whereC =:= CC[A], this can be done by mixing in thescala.collection.IterableFactoryDefaults trait, which implements the method usingiterableFactory.As witnessed by the
@uncheckedVarianceannotation, using this method might be unsound. However, as long as it is called with anIterable[A]obtained fromthiscollection (as it is the case in the implementations of operations where we use aView[A]), it is safe.- Inherited from:
- IterableFactoryDefaults
- Source
- Iterable.scala
Returns the value associated with a key, or a default value if the key is not contained in the map.
Returns the value associated with a key, or a default value if the key is not contained in the map.
Type parameters
- V1
the result type of the default computation.
Value parameters
- default
a computation that yields a default value in case no binding for
keyis found in the map.- key
the key.
Attributes
Partitions this iterable collection into a map of iterable collections according to some discriminator function.
Partitions this iterable collection into a map of iterable collections according to some discriminator function.
Note: Even when applied to a view or a lazy collection it will always force the elements.
Type parameters
- K
the type of keys returned by the discriminator function.
Value parameters
- f
the discriminator function.
Attributes
- Returns
A map from keys to iterable collections such that the following invariant holds:
(xs groupBy f)(k) = xs filter (x => f(x) == k)That is, every key
kis bound to a iterable collection of those elementsxfor whichf(x)equalsk.- Inherited from:
- IterableOps
- Source
- Iterable.scala
Partitions this iterable collection into a map of iterable collections according to a discriminator functionkey.
Partitions this iterable collection into a map of iterable collections according to a discriminator functionkey. Each element in a group is transformed into a value of typeB using thevalue function.
It is equivalent togroupBy(key).mapValues(_.map(f)), but more efficient.
case class User(name: String, age: Int)def namesByAge(users: Seq[User]): Map[Int, Seq[String]] = users.groupMap(_.age)(_.name)Note: Even when applied to a view or a lazy collection it will always force the elements.
Type parameters
- B
the type of values returned by the transformation function
- K
the type of keys returned by the discriminator function
Value parameters
- f
the element transformation function
- key
the discriminator function
Attributes
- Inherited from:
- IterableOps
- Source
- Iterable.scala
Partitions this iterable collection into a map according to a discriminator functionkey.
Partitions this iterable collection into a map according to a discriminator functionkey. All the values that have the same discriminator are then transformed by thef function and then reduced into a single value with thereduce function.
It is equivalent togroupBy(key).mapValues(_.map(f).reduce(reduce)), but more efficient.
def occurrences[A](as: Seq[A]): Map[A, Int] = as.groupMapReduce(identity)(_ => 1)(_ + _)Note: Even when applied to a view or a lazy collection it will always force the elements.
Attributes
- Inherited from:
- IterableOps
- Source
- Iterable.scala
Partitions elements in fixed size iterable collections.
Partitions elements in fixed size iterable collections.
Value parameters
- size
the number of elements per group
Attributes
- Returns
An iterator producing iterable collections of size
size, except the last will be less than sizesizeif the elements don't divide evenly.- See also
scala.collection.Iterator, method
grouped- Inherited from:
- IterableOps
- Source
- Iterable.scala
Selects the first element of this iterable collection.
Selects the first element of this iterable collection.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Attributes
- Returns
the first element of this iterable collection.
- Throws
NoSuchElementExceptionif the iterable collection is empty.
- Inherited from:
- IterableOps
- Source
- Iterable.scala
Optionally selects the first element.
Optionally selects the first element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Attributes
- Returns
the first element of this iterable collection if it is nonempty,
Noneif it is empty.- Inherited from:
- IterableOps
- Source
- Iterable.scala
The initial part of the collection without its last element.
The initial part of the collection without its last element.
Note: Even when applied to a view or a lazy collection it will always force the elements.
Attributes
- Inherited from:
- IterableOps
- Source
- Iterable.scala
Iterates over the inits of this iterable collection.
Iterates over the inits of this iterable collection. The first value will be this iterable collection and the final one will be an empty iterable collection, with the intervening values the results of successive applications ofinit.
Note: Even when applied to a view or a lazy collection it will always force the elements.
Attributes
- Returns
an iterator over all the inits of this iterable collection
- Example
List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)- Inherited from:
- IterableOps
- Source
- Iterable.scala
Tests whether this map contains a binding for a key.
Tests whether this iterable collection can be repeatedly traversed.
Tests whether this iterable collection can be repeatedly traversed. Always true for Iterables and false for Iterators unless overridden.
Attributes
- Returns
trueif it is repeatedly traversable,falseotherwise.- Definition Classes
- Inherited from:
- IterableOps
- Source
- Iterable.scala
The companion object of this view, providing various factory methods.
The companion object of this view, providing various factory methods.
Attributes
- Note
When implementing a custom collection type and refining
CCto the new type, this method needs to be overridden to return a factory for the new type (the compiler will issue an error otherwise).- Definition Classes
- Inherited from:
- View
- Source
- View.scala
A set representing the keys contained by this map.
A set representing the keys contained by this map.
For efficiency the resulting set may be a view (maintaining a reference to the map and reflecting modifications to the map), but it may also be a strict collection without reference to the map.
To ensure an independent strict collection, use
m.keysIterator.toSetTo obtain a view on the keys, use
scala.collection.View.fromIteratorProvider(m.keysIterator)
Attributes
Creates a view over all keys of this map.
Creates a view over all keys of this map.
Attributes
- Returns
the keys of this map as a view.
- Definition Classes
- Inherited from:
- MapView
- Source
- MapView.scala
Selects the last element.
Selects the last element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Attributes
- Returns
The last element of this iterable collection.
- Throws
NoSuchElementExceptionIf the iterable collection is empty.
- Inherited from:
- IterableOps
- Source
- Iterable.scala
Optionally selects the last element.
Optionally selects the last element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Attributes
- Returns
the last element of this iterable collection$ if it is nonempty,
Noneif it is empty.- Inherited from:
- IterableOps
- Source
- Iterable.scala
Analogous tozip except that the elements in each collection are not consumed until a strict operation is invoked on the returnedLazyZip2 decorator.
Analogous tozip except that the elements in each collection are not consumed until a strict operation is invoked on the returnedLazyZip2 decorator.
Calls tolazyZip can be chained to support higher arities (up to 4) without incurring the expense of constructing and deconstructing intermediary tuples.
val xs = List(1, 2, 3)val res = (xs lazyZip xs lazyZip xs lazyZip xs).map((a, b, c, d) => a + b + c + d)// res == List(4, 8, 12)Type parameters
- B
the type of the second element in each eventual pair
Value parameters
- that
the iterable providing the second element of each eventual pair
Attributes
- Returns
a decorator
LazyZip2that allows strict operations to be performed on the lazily evaluated pairs or chained calls tolazyZip. Implicit conversion toIterable[(A, B)]is also supported.- Inherited from:
- Iterable
- Source
- Iterable.scala
Turns this partial function into a plain function returning anOption result.
Turns this partial function into a plain function returning anOption result.
Attributes
- Returns
a function that takes an argument
xtoSome(this(x))ifthisis defined forx, and toNoneotherwise.- See also
Function.unlift
- Inherited from:
- PartialFunction
- Source
- PartialFunction.scala
Builds a new iterable collection by applying a function to all elements of this iterable collection.
Builds a new iterable collection by applying a function to all elements of this iterable collection.
Type parameters
- B
the element type of the returned iterable collection.
Value parameters
- f
the function to apply to each element.
Attributes
- Returns
a new iterable collection resulting from applying the given function
fto each element of this iterable collection and collecting the results.- Inherited from:
- IterableOps
- Source
- Iterable.scala
Builds a new map by applying a function to all elements of this map.
The companion object of this map, providing various factory methods.
The companion object of this map, providing various factory methods.
Attributes
- Note
When implementing a custom collection type and refining
CCto the new type, this method needs to be overridden to return a factory for the new type (the compiler will issue an error otherwise).- Inherited from:
- MapView
- Source
- MapView.scala
Transforms this map by applying a function to every retrieved value.
Transforms this map by applying a function to every retrieved value.
Value parameters
- f
the function used to transform values of this map.
Attributes
- 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
- Inherited from:
- MapView
- Source
- MapView.scala
Finds the largest element.
Finds the largest element.
Note: will not terminate for infinite-sized collections.
Type parameters
- B
The type over which the ordering is defined.
Value parameters
- ord
An ordering to be used for comparing elements.
Attributes
- Returns
the largest element of this collection with respect to the ordering
ord.- Throws
UnsupportedOperationExceptionif this collection is empty.
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Finds the first element which yields the largest value measured by functionf.
Finds the first element which yields the largest value measured by functionf.
Note: will not terminate for infinite-sized collections.
Type parameters
- B
The result type of the function
f.
Value parameters
- cmp
An ordering to be used for comparing elements.
- f
The measuring function.
Attributes
- Returns
the first element of this collection with the largest value measured by function
fwith respect to the orderingcmp.- Throws
UnsupportedOperationExceptionif this collection is empty.
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Finds the first element which yields the largest value measured by functionf.
Finds the first element which yields the largest value measured by functionf.
Note: will not terminate for infinite-sized collections.
Type parameters
- B
The result type of the function
f.
Value parameters
- cmp
An ordering to be used for comparing elements.
- f
The measuring function.
Attributes
- Returns
an option value containing the first element of this collection with the largest value measured by function
fwith respect to the orderingcmp.- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Finds the largest element.
Finds the largest element.
Note: will not terminate for infinite-sized collections.
Type parameters
- B
The type over which the ordering is defined.
Value parameters
- ord
An ordering to be used for comparing elements.
Attributes
- Returns
an option value containing the largest element of this collection with respect to the ordering
ord.- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Finds the smallest element.
Finds the smallest element.
Note: will not terminate for infinite-sized collections.
Type parameters
- B
The type over which the ordering is defined.
Value parameters
- ord
An ordering to be used for comparing elements.
Attributes
- Returns
the smallest element of this collection with respect to the ordering
ord.- Throws
UnsupportedOperationExceptionif this collection is empty.
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Finds the first element which yields the smallest value measured by functionf.
Finds the first element which yields the smallest value measured by functionf.
Note: will not terminate for infinite-sized collections.
Type parameters
- B
The result type of the function
f.
Value parameters
- cmp
An ordering to be used for comparing elements.
- f
The measuring function.
Attributes
- Returns
the first element of this collection with the smallest value measured by function
fwith respect to the orderingcmp.- Throws
UnsupportedOperationExceptionif this collection is empty.
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Finds the first element which yields the smallest value measured by functionf.
Finds the first element which yields the smallest value measured by functionf.
Note: will not terminate for infinite-sized collections.
Type parameters
- B
The result type of the function
f.
Value parameters
- cmp
An ordering to be used for comparing elements.
- f
The measuring function.
Attributes
- Returns
an option value containing the first element of this collection with the smallest value measured by function
fwith respect to the orderingcmp.- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Finds the smallest element.
Finds the smallest element.
Note: will not terminate for infinite-sized collections.
Type parameters
- B
The type over which the ordering is defined.
Value parameters
- ord
An ordering to be used for comparing elements.
Attributes
- Returns
an option value containing the smallest element of this collection with respect to the ordering
ord.- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Displays all elements of this collection in a string.
Displays all elements of this collection in a string.
Delegates to addString, which can be overridden.
Attributes
- Returns
a string representation of this collection. In the resulting string the string representations (w.r.t. the method
toString) of all elements of this collection follow each other without any separator string.- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Displays all elements of this collection in a string using a separator string.
Displays all elements of this collection in a string using a separator string.
Delegates to addString, which can be overridden.
Value parameters
- sep
the separator string.
Attributes
- Returns
a string representation of this collection. In the resulting string the string representations (w.r.t. the method
toString) of all elements of this collection are separated by the stringsep.- Example
List(1, 2, 3).mkString("|") = "1|2|3"- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Displays all elements of this collection in a string using start, end, and separator strings.
Displays all elements of this collection in a string using start, end, and separator strings.
Delegates to addString, which can be overridden.
Value parameters
- end
the ending string.
- sep
the separator string.
- start
the starting string.
Attributes
- Returns
a string representation of this collection. The resulting string begins with the string
startand ends with the stringend. Inside, the string representations (w.r.t. the methodtoString) of all elements of this collection are separated by the stringsep.- Example
List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Attributes
- Returns
a strict builder for the same collection type. Note that in the case of lazy collections (e.g.scala.collection.View orscala.collection.immutable.LazyList), it is possible to implement this method but the resulting
Builderwill break laziness. As a consequence, operations should preferably be implemented withfromSpecificinstead of this method.- Note
When implementing a custom collection type and refining
Cto the new type, this method needs to be overridden (the compiler will issue an error otherwise). In the common case whereC =:= CC[A], this can be done by mixing in thescala.collection.IterableFactoryDefaults trait, which implements the method usingiterableFactory.As witnessed by the
@uncheckedVarianceannotation, using this method might be unsound. However, as long as the returned builder is only fed withAvalues taken fromthisinstance, it is safe.- Inherited from:
- IterableFactoryDefaults
- Source
- Iterable.scala
Tests whether the collection is not empty.
Tests whether the collection is not empty.
Attributes
- Returns
trueif the collection contains at least one element,falseotherwise.- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Composes this partial function with a fallback partial function which gets applied where this partial function is not defined.
Composes this partial function with a fallback partial function which gets applied where this partial function is not defined.
Type parameters
- A1
the argument type of the fallback function
- B1
the result type of the fallback function
Value parameters
- that
the fallback function
Attributes
- Returns
a partial function which has as domain the union of the domains of this partial function and
that. The resulting partial function takesxtothis(x)wherethisis defined, and tothat(x)where it is not.- Inherited from:
- PartialFunction
- Source
- PartialFunction.scala
A pair of, first, all elements that satisfy predicatep and, second, all elements that do not.
A pair of, first, all elements that satisfy predicatep and, second, all elements that do not. Interesting because it splits a collection in two.
The default implementation provided here needs to traverse the collection twice. Strict collections have an overridden version ofpartition inStrictOptimizedIterableOps, which requires only a single traversal.
Attributes
- Definition Classes
- Inherited from:
- MapView
- Source
- MapView.scala
Applies a functionf to each element of the iterable collection and returns a pair of iterable collections: the first one made of those values returned byf that were wrapped inscala.util.Left, and the second one made of those wrapped inscala.util.Right.
Applies a functionf to each element of the iterable collection and returns a pair of iterable collections: the first one made of those values returned byf that were wrapped inscala.util.Left, and the second one made of those wrapped inscala.util.Right.
Example:
val xs = Iterable(1, "one", 2, "two", 3, "three") partitionMap { case i: Int => Left(i) case s: String => Right(s)}// xs == (Iterable(1, 2, 3),// Iterable(one, two, three))Type parameters
- A1
the element type of the first resulting collection
- A2
the element type of the second resulting collection
Value parameters
- f
the 'split function' mapping the elements of this iterable collection to anscala.util.Either
Attributes
- Returns
a pair of iterable collections: the first one made of those values returned by
fthat were wrapped inscala.util.Left, and the second one made of those wrapped inscala.util.Right.- Inherited from:
- IterableOps
- Source
- Iterable.scala
Multiplies together the elements of this collection.
Multiplies together the elements of this collection.
The default implementation usesreduce for a known non-empty collection,foldLeft otherwise.
Note: will not terminate for infinite-sized collections.
Type parameters
- B
the result type of the
*operator.
Value parameters
- num
an implicit parameter defining a set of numeric operations which includes the
*operator to be used in forming the product.
Attributes
- Returns
the product of all elements of this collection with respect to the
*operator innum.- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Applies the given binary operatorop to all elements of this collection.
Applies the given binary operatorop to all elements of this collection.
For each application of the operator, each operand is either an element of this collection or another such application of the operator. The order of applications of the operator is unspecified and may be nondeterministic. Each element appears exactly once in the computation.
If this collection is ordered, then for any application of the operator, the element(s) appearing in the left operand will precede those in the right.
Note: might return different results for different runs, unless either of the following conditions is met: (1) the operator is associative, and the underlying collection type is ordered; or (2) the operator is associative and commutative.
Note: will not terminate for infinite-sized collections.
Type parameters
- B
The type parameter for the binary operator, a supertype of
A.
Value parameters
- op
A binary operator; must be associative for the result to always be the same across runs.
Attributes
- Returns
The result of applying
opbetween all the elements if the collection is nonempty.- Throws
UnsupportedOperationExceptionif this collection is empty.
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Applies the given binary operatorop to all elements of this collection, going left to right.
Applies the given binary operatorop to all elements of this collection, going left to right.
"Going left to right" only makes sense if this collection is ordered: then ifx1,x2, ...,xn are the elements of this collection, the result isop( op( op( ... op(x1, x2) ... ), xn-1), xn).
If this collection is not ordered, then for each application of the operator, each right operand is an element. In addition, the leftmost operand is the first element of this collection and each other left operand is itself an application of the operator. Each element appears exactly once in the computation.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
Note: will not terminate for infinite-sized collections.
Type parameters
- B
The result type of the binary operator, a supertype of
A.
Value parameters
- op
A binary operator.
Attributes
- Returns
The result of applying
opto all elements of this collection, going left to right.- Throws
UnsupportedOperationExceptionif this collection is empty.
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
If this collection is nonempty, reduces it with the given binary operatorop, going left to right.
If this collection is nonempty, reduces it with the given binary operatorop, going left to right.
The behavior is the same asreduceLeft except that the value isNone if the collection is empty. Each element appears exactly once in the computation.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
Note: will not terminate for infinite-sized collections.
Type parameters
- B
The result type of the binary operator, a supertype of
A.
Value parameters
- op
A binary operator.
Attributes
- Returns
The result of reducing this collection with
opgoing left to right if the collection is nonempty, inside aSome, andNoneotherwise.- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
If this collection is nonempty, reduces it with the given binary operatorop.
If this collection is nonempty, reduces it with the given binary operatorop.
The behavior is the same asreduce except that the value isNone if the collection is empty. The order of applications of the operator is unspecified and may be nondeterministic. Each element appears exactly once in the computation.
Note: might return different results for different runs, unless either of the following conditions is met: (1) the operator is associative, and the underlying collection type is ordered; or (2) the operator is associative and commutative.
Note: will not terminate for infinite-sized collections.
Type parameters
- B
A type parameter for the binary operator, a supertype of
A.
Value parameters
- op
A binary operator; must be associative for the result to always be the same across runs.
Attributes
- Returns
The result of reducing this collection with
opif the collection is nonempty, inside aSome, andNoneotherwise.- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Applies the given binary operatorop to all elements of this collection, going right to left.
Applies the given binary operatorop to all elements of this collection, going right to left.
"Going right to left" only makes sense if this collection is ordered: then ifx1,x2, ...,xn are the elements of this collection, the result isop(x1, op(x2, op( ... op(xn-1, xn) ... ))).
If this collection is not ordered, then for each application of the operator, each left operand is an element. In addition, the rightmost operand is the last element of this collection and each other right operand is itself an application of the operator. Each element appears exactly once in the computation.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
Note: will not terminate for infinite-sized collections.
Type parameters
- B
The result type of the binary operator, a supertype of
A.
Value parameters
- op
A binary operator.
Attributes
- Returns
The result of applying
opto all elements of this collection, going right to left.- Throws
UnsupportedOperationExceptionif this collection is empty.
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
If this collection is nonempty, reduces it with the given binary operatorop, going right to left.
If this collection is nonempty, reduces it with the given binary operatorop, going right to left.
The behavior is the same asreduceRight except that the value isNone if the collection is empty. Each element appears exactly once in the computation.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
Note: will not terminate for infinite-sized collections.
Type parameters
- B
The result type of the binary operator, a supertype of
A.
Value parameters
- op
A binary operator.
Attributes
- Returns
The result of reducing this collection with
opgoing right to left if the collection is nonempty, inside aSome, andNoneotherwise.- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Attributes
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Composes this partial function with an action function which gets applied to results of this partial function.
Composes this partial function with an action function which gets applied to results of this partial function. The action function is invoked only for its side effects; its result is ignored.
Note that expressionpf.runWith(action)(x) is equivalent to
if(pf isDefinedAt x) { action(pf(x)); true } else falseexcept thatrunWith is implemented viaapplyOrElse and thus potentially more efficient. UsingrunWith avoids double evaluation of pattern matchers and guards for partial function literals.
Value parameters
- action
the action function
Attributes
- Returns
a function which maps arguments
xtoisDefinedAt(x). The resulting function runsaction(this(x))wherethisis defined.- See also
applyOrElse.- Inherited from:
- PartialFunction
- Source
- PartialFunction.scala
Computes a prefix scan of the elements of the collection.
Computes a prefix scan of the elements of the collection.
Note: The neutral elementz may be applied more than once.
Type parameters
- B
element type of the resulting collection
Value parameters
- op
the associative operator for the scan
- z
neutral element for the operator
op
Attributes
- Returns
a new iterable collection containing the prefix scan of the elements in this iterable collection
- Inherited from:
- IterableOps
- Source
- Iterable.scala
Produces a iterable collection containing cumulative results of applying the operator going left to right, including the initial value.
Produces a iterable collection containing cumulative results of applying the operator going left to right, including the initial value.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Type parameters
- B
the type of the elements in the resulting collection
Value parameters
- op
the binary operator applied to the intermediate result and the element
- z
the initial value
Attributes
- Returns
collection with intermediate results
- Inherited from:
- IterableOps
- Source
- Iterable.scala
Produces a collection containing cumulative results of applying the operator going right to left.
Produces a collection containing cumulative results of applying the operator going right to left. The head of the collection is the last cumulative result.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Note: Even when applied to a view or a lazy collection it will always force the elements.
Example:
List(1, 2, 3, 4).scanRight(0)(_ + _) == List(10, 9, 7, 4, 0)Type parameters
- B
the type of the elements in the resulting collection
Value parameters
- op
the binary operator applied to the intermediate result and the element
- z
the initial value
Attributes
- Returns
collection with intermediate results
- Inherited from:
- IterableOps
- Source
- Iterable.scala
The size of this collection.
The size of this collection.
Note: will not terminate for infinite-sized collections.
Attributes
- Returns
the number of elements in this collection.
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Compares the size of this iterable collection to the size of anotherIterable.
Compares the size of this iterable collection to the size of anotherIterable.
Value parameters
- that
the
Iterablewhose size is compared with this iterable collection's size.
Attributes
- Returns
A value
xwherex < 0 if this.size < that.sizex == 0 if this.size == that.sizex > 0 if this.size > that.sizeThe method as implemented here does not call
sizedirectly; its running time isO(this.size min that.size)instead ofO(this.size + that.size). The method should be overridden if computingsizeis cheap andknownSizereturns-1.- Inherited from:
- IterableOps
- Source
- Iterable.scala
Compares the size of this iterable collection to a test value.
Compares the size of this iterable collection to a test value.
Value parameters
- otherSize
the test value that gets compared with the size.
Attributes
- Returns
A value
xwherex < 0 if this.size < otherSizex == 0 if this.size == otherSizex > 0 if this.size > otherSizeThe method as implemented here does not call
sizedirectly; its running time isO(size min otherSize)instead ofO(size). The method should be overridden if computingsizeis cheap andknownSizereturns-1.- See also
- Inherited from:
- IterableOps
- Source
- Iterable.scala
Returns a value class containing operations for comparing the size of this iterable collection to a test value.
Returns a value class containing operations for comparing the size of this iterable collection to a test value.
These operations are implemented in terms ofsizeCompare(Int), and allow the following more readable usages:
this.sizeIs < size // this.sizeCompare(size) < 0this.sizeIs <= size // this.sizeCompare(size) <= 0this.sizeIs == size // this.sizeCompare(size) == 0this.sizeIs != size // this.sizeCompare(size) != 0this.sizeIs >= size // this.sizeCompare(size) >= 0this.sizeIs > size // this.sizeCompare(size) > 0Attributes
- Inherited from:
- IterableOps
- Source
- Iterable.scala
Selects an interval of elements.
Selects an interval of elements. The returned iterable collection is made up of all elementsx which satisfy the invariant:
from <= indexOf(x) < untilNote: might return different results for different runs, unless the underlying collection type is ordered.
Value parameters
- from
the lowest index to include from this iterable collection.
- until
the lowest index to EXCLUDE from this iterable collection.
Attributes
- Returns
a iterable collection containing the elements greater than or equal to index
fromextending up to (but not including) indexuntilof this iterable collection.- Inherited from:
- IterableOps
- Source
- Iterable.scala
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)
The returned iterator will be empty when called on an empty collection. The last element the iterator produces may be smaller than the window size when the original collection isn't exhausted by the window before it and its last element isn't skipped by the step before it.
Value parameters
- size
the number of elements per group
- step
the distance between the first elements of successive groups
Attributes
- Returns
An iterator producing iterable collections of size
size, except the last element (which may be the only element) will be smaller if there are fewer thansizeelements remaining to be grouped.- See also
scala.collection.Iterator, method
sliding- Example
List(1, 2, 3, 4, 5).sliding(2, 2) = Iterator(List(1, 2), List(3, 4), List(5))List(1, 2, 3, 4, 5, 6).sliding(2, 3) = Iterator(List(1, 2), List(4, 5))- Inherited from:
- IterableOps
- Source
- Iterable.scala
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done ingrouped.)
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done ingrouped.)
An empty collection returns an empty iterator, and a non-empty collection containing fewer elements than the window size returns an iterator that will produce the original collection as its only element.
Value parameters
- size
the number of elements per group
Attributes
- Returns
An iterator producing iterable collections of size
size, except for a non-empty collection with less thansizeelements, which returns an iterator that produces the source collection itself as its only element.- See also
scala.collection.Iterator, method
sliding- Example
List().sliding(2) = empty iteratorList(1).sliding(2) = Iterator(List(1))List(1, 2).sliding(2) = Iterator(List(1, 2))List(1, 2, 3).sliding(2) = Iterator(List(1, 2), List(2, 3))- Inherited from:
- IterableOps
- Source
- Iterable.scala
Splits this iterable collection into a prefix/suffix pair according to a predicate.
Splits this iterable collection into a prefix/suffix pair according to a predicate.
Note:c span p is equivalent to (but possibly more efficient than)(c takeWhile p, c dropWhile p), provided the evaluation of the predicatep does not cause any side-effects.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parameters
- p
the test predicate
Attributes
- Returns
a pair consisting of the longest prefix of this iterable collection whose elements all satisfy
p, and the rest of this iterable collection.- Inherited from:
- IterableOps
- Source
- Iterable.scala
Splits this iterable collection into a prefix/suffix pair at a given position.
Splits this iterable collection into a prefix/suffix pair at a given position.
Note:c splitAt n is equivalent to (but possibly more efficient than)(c take n, c drop n).
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parameters
- n
the position at which to split.
Attributes
- Returns
a pair of iterable collections consisting of the first
nelements of this iterable collection, and the other elements.- Definition Classes
- Inherited from:
- IterableOps
- Source
- Iterable.scala
Returns ascala.collection.Stepper for the elements of this collection.
Returns ascala.collection.Stepper for the elements of this collection.
The Stepper enables creating a Java stream to operate on the collection, seescala.jdk.StreamConverters. For collections holding primitive values, the Stepper can be used as an iterator which doesn't box the elements.
The implicitscala.collection.StepperShape parameter defines the resulting Stepper type according to the element type of this collection.
For collections of
Int,Short,ByteorChar, anscala.collection.IntStepper is returnedFor collections of
DoubleorFloat, ascala.collection.DoubleStepper is returnedFor collections of
Longascala.collection.LongStepper is returnedFor any other element type, anscala.collection.AnyStepper is returned
Note that this method is overridden in subclasses and the return type is refined toS with EfficientSplit, for examplescala.collection.IndexedSeqOps.stepper. For Steppers marked withscala.collection.Stepper.EfficientSplit, the converters inscala.jdk.StreamConverters allow creating parallel streams, whereas bare Steppers can be converted only to sequential streams.
Attributes
- Inherited from:
- IterableOnce
- Source
- IterableOnce.scala
Sums the elements of this collection.
Sums the elements of this collection.
The default implementation usesreduce for a known non-empty collection,foldLeft otherwise.
Note: will not terminate for infinite-sized collections.
Type parameters
- B
the result type of the
+operator.
Value parameters
- num
an implicit parameter defining a set of numeric operations which includes the
+operator to be used in forming the sum.
Attributes
- Returns
the sum of all elements of this collection with respect to the
+operator innum.- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
The rest of the collection without its first element.
The rest of the collection without its first element.
Attributes
- Inherited from:
- IterableOps
- Source
- Iterable.scala
Iterates over the tails of this iterable collection.
Iterates over the tails of this iterable collection. The first value will be this iterable collection and the final one will be an empty iterable collection, with the intervening values the results of successive applications oftail.
Attributes
- Returns
an iterator over all the tails of this iterable collection
- Example
List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)- Inherited from:
- IterableOps
- Source
- Iterable.scala
Selects the firstn elements.
Selects the firstn elements.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parameters
- n
the number of elements to take from this iterable collection.
Attributes
- Returns
a iterable collection consisting only of the first
nelements of this iterable collection, or else the whole iterable collection, if it has less thannelements. Ifnis negative, returns an empty iterable collection.- Inherited from:
- IterableOps
- Source
- Iterable.scala
Selects the lastn elements.
Selects the lastn elements.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parameters
- n
the number of elements to take from this iterable collection.
Attributes
- Returns
a iterable collection consisting only of the last
nelements of this iterable collection, or else the whole iterable collection, if it has less thannelements. Ifnis negative, returns an empty iterable collection.- Inherited from:
- IterableOps
- Source
- Iterable.scala
Takes longest prefix of elements that satisfy a predicate.
Takes longest prefix of elements that satisfy a predicate.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parameters
- p
The predicate used to test elements.
Attributes
- Returns
the longest prefix of this iterable collection whose elements all satisfy the predicate
p.- Inherited from:
- IterableOps
- Source
- Iterable.scala
Applies a side-effecting function to each element in this collection.
Applies a side-effecting function to each element in this collection. Strict collections will applyf to their elements immediately, while lazy collections like Views and LazyLists will only applyf on each element if and when that element is evaluated, and each time that element is evaluated.
Type parameters
- U
the return type of f
Value parameters
- f
a function to apply to each element in this view
Attributes
- Returns
The same logical collection as this
- Definition Classes
- Inherited from:
- MapView
- Source
- MapView.scala
Given a collection factoryfactory, converts this collection to the appropriate representation for the current element typeA.
Given a collection factoryfactory, converts this collection to the appropriate representation for the current element typeA. Example uses:
xs.to(List)xs.to(ArrayBuffer)xs.to(BitSet) // for xs: Iterable[Int]Attributes
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Converts this collection to anArray.
Converts this collection to anArray.
Implementation note: DO NOT callArray.from from this method.
Type parameters
- B
The type of elements of the result, a supertype of
A.
Attributes
- Returns
This collection as an
Array[B].- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Converts this collection to aBuffer.
Converts this collection to aBuffer.
Type parameters
- B
The type of elements of the result, a supertype of
A.
Attributes
- Returns
This collection as a
Buffer[B].- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Converts this collection to anIndexedSeq.
Converts this collection to anIndexedSeq.
Attributes
- Returns
This collection as an
IndexedSeq[A].- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Converts this collection to aList.
Converts this collection to aList.
Attributes
- Returns
This collection as a
List[A].- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Converts this collection to aMap, given an implicit coercion from the collection's type to a key-value tuple.
Converts this collection to aMap, given an implicit coercion from the collection's type to a key-value tuple.
Type parameters
- K
The key type for the resulting map.
- V
The value type for the resulting map.
Value parameters
- ev
An implicit coercion from
Ato[K, V].
Attributes
- Returns
This collection as a
Map[K, V].- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Attributes
- Returns
This collection as a
Seq[A]. This is equivalent toto(Seq)but might be faster.- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Converts this collection to aSet.
Converts this collection to aSet.
Type parameters
- B
The type of elements of the result, a supertype of
A.
Attributes
- Returns
This collection as a
Set[B].- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Converts this view to a string.
Converts this view to a string.
Attributes
- Returns
a string representation of this collection. By default this string consists of the
classNameof this view, followed by all elements separated by commas and enclosed in parentheses.- Definition Classes
- Inherited from:
- MapView
- Source
- MapView.scala
Converts this collection to aVector.
Converts this collection to aVector.
Attributes
- Returns
This collection as a
Vector[A].- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Transposes this iterable collection of iterable collections into a iterable collection of iterable collections.
Transposes this iterable collection of iterable collections into a iterable collection of iterable collections.
The resulting collection's type will be guided by the static type of iterable collection. For example:
val xs = List( Set(1, 2, 3), Set(4, 5, 6)).transpose// xs == List(// List(1, 4),// List(2, 5),// List(3, 6))val ys = Vector( List(1, 2, 3), List(4, 5, 6)).transpose// ys == Vector(// Vector(1, 4),// Vector(2, 5),// Vector(3, 6))Note: Even when applied to a view or a lazy collection it will always force the elements.
Type parameters
- B
the type of the elements of each iterable collection.
Value parameters
- asIterable
an implicit conversion which asserts that the element type of this iterable collection is an
Iterable.
Attributes
- Returns
a two-dimensional iterable collection of iterable collections which has asnth row thenth column of this iterable collection.
- Throws
IllegalArgumentExceptionif all collections in this iterable collection are not of the same size.
- Inherited from:
- IterableOps
- Source
- Iterable.scala
Tries to extract aB from anA in a pattern matching expression.
Tries to extract aB from anA in a pattern matching expression.
Attributes
- Inherited from:
- PartialFunction
- Source
- PartialFunction.scala
Converts this iterable collection of pairs into two collections of the first and second half of each pair.
Converts this iterable collection of pairs into two collections of the first and second half of each pair.
val xs = Iterable( (1, "one"), (2, "two"), (3, "three")).unzip// xs == (Iterable(1, 2, 3),// Iterable(one, two, three))Type parameters
- A1
the type of the first half of the element pairs
- A2
the type of the second half of the element pairs
Value parameters
- asPair
an implicit conversion which asserts that the element type of this iterable collection is a pair.
Attributes
- Returns
a pair of iterable collections, containing the first, respectively second half of each element pair of this iterable collection.
- Inherited from:
- IterableOps
- Source
- Iterable.scala
Converts this iterable collection of triples into three collections of the first, second, and third element of each triple.
Converts this iterable collection of triples into three collections of the first, second, and third element of each triple.
val xs = Iterable( (1, "one", '1'), (2, "two", '2'), (3, "three", '3')).unzip3// xs == (Iterable(1, 2, 3),// Iterable(one, two, three),// Iterable(1, 2, 3))Type parameters
- A1
the type of the first member of the element triples
- A2
the type of the second member of the element triples
- A3
the type of the third member of the element triples
Value parameters
- asTriple
an implicit conversion which asserts that the element type of this iterable collection is a triple.
Attributes
- Returns
a triple of iterable collections, containing the first, second, respectively third member of each element triple of this iterable collection.
- Inherited from:
- IterableOps
- Source
- Iterable.scala
Creates a view over all values of this map.
Creates a view over all values of this map.
Attributes
- Returns
the values of this map as a view.
- Definition Classes
- Inherited from:
- MapView
- Source
- MapView.scala
A view over the elements of this collection.
A view over the elements of this collection.
Attributes
- Definition Classes
- Inherited from:
- MapView
- Source
- MapView.scala
Creates a non-strict filter of this view.
Creates a non-strict filter of this view.
Note: the difference betweenc filter p andc withFilter p is that the former creates a new collection, whereas the latter only restricts the domain of subsequentmap,flatMap,foreach, andwithFilter operations.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parameters
- p
the predicate used to test elements.
Attributes
- Returns
an object of class
WithFilter, which supportsmap,flatMap,foreach, andwithFilteroperations. All these operations apply to those elements of this view which satisfy the predicatep.- Definition Classes
- Inherited from:
- MapView
- Source
- MapView.scala
Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs.
Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs. If one of the two collections is longer than the other, its remaining elements are ignored.
Type parameters
- B
the type of the second half of the returned pairs
Value parameters
- that
The iterable providing the second half of each result pair
Attributes
- Returns
a new iterable collection containing pairs consisting of corresponding elements of this iterable collection and
that. The length of the returned collection is the minimum of the lengths of this iterable collection andthat.- Inherited from:
- IterableOps
- Source
- Iterable.scala
Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs.
Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs. If one of the two collections is shorter than the other, placeholder elements are used to extend the shorter collection to the length of the longer.
Value parameters
- that
the iterable providing the second half of each result pair
- thatElem
the element to be used to fill up the result if
thatis shorter than this iterable collection.- thisElem
the element to be used to fill up the result if this iterable collection is shorter than
that.
Attributes
- Returns
a new collection of the type of this iterable collection containing pairs consisting of corresponding elements of this iterable collection and
that. The length of the returned collection is the maximum of the lengths of this iterable collection andthat. If this iterable collection is shorter thanthat,thisElemvalues are used to pad the result. Ifthatis shorter than this iterable collection,thatElemvalues are used to pad the result.- Inherited from:
- IterableOps
- Source
- Iterable.scala
Zips this iterable collection with its indices.
Zips this iterable collection with its indices.
Attributes
- Returns
A new iterable collection containing pairs consisting of all elements of this iterable collection paired with their index. Indices start at
0.- Example
List("a", "b", "c").zipWithIndex == List(("a", 0), ("b", 1), ("c", 2))- Inherited from:
- IterableOps
- Source
- Iterable.scala
Deprecated and Inherited methods
Attributes
- Deprecated
[Since version 2.13.0]Use ++ instead of ++: for collections of type Iterable- Inherited from:
- IterableOps
- Source
- Iterable.scala
Attributes
- Deprecated
[Since version 2.13.0]Use foldLeft instead of /:- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Attributes
- Deprecated
[Since version 2.13.0]Use foldRight instead of :\\- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Aggregates the results of applying an operator to subsequent elements.
Aggregates the results of applying an operator to subsequent elements.
Since this method degenerates tofoldLeft for sequential (non-parallel) collections, where the combining operation is ignored, it is advisable to preferfoldLeft for that case.
Forparallel collections, use theaggregate method specified byscala.collection.parallel.ParIterableLike.
Type parameters
- B
the result type, produced by
seqop,combop, and by this function as a final result.
Value parameters
- combop
an associative operator for combining sequential results, unused for sequential collections.
- seqop
the binary operator used to accumulate the result.
- z
the start value, a neutral element for
seqop.
Attributes
- Deprecated
[Since version 2.13.0]For sequential collections, prefer `foldLeft(z)(seqop)`. For parallel collections, use `ParIterableLike#aggregate`.- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Attributes
- Deprecated
[Since version 2.13.0]Use iterableFactory instead- Inherited from:
- IterableOps
- Source
- Iterable.scala
Attributes
- Deprecated
[Since version 2.13.0]Use `dest ++= coll` instead- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Attributes
- Deprecated
[Since version 2.13.0]Views no longer know about their underlying collection type; .force always returns an IndexedSeq- Inherited from:
- View
- Source
- View.scala
Tests whether this collection is known to have a finite size.
Tests whether this collection is known to have a finite size. All strict collections are known to have finite size. For a non-strict collection such asStream, the predicate returnstrue if all elements have been computed. It returnsfalse if the stream is not yet evaluated to the end. Non-empty Iterators usually returnfalse even if they were created from a collection with a known finite size.
Note: many collection methods will not work on collections of infinite sizes. The typical failure mode is an infinite loop. These methods always attempt a traversal without checking first thathasDefiniteSize returnstrue. However, checkinghasDefiniteSize can provide an assurance that size is well-defined and non-termination is not a concern.
Attributes
- Returns
trueif this collection is known to have finite size,falseotherwise.- See also
method
knownSizefor a more useful alternative- Deprecated
[Since version 2.13.0]Check .knownSize instead of .hasDefiniteSize for more actionable information (see scaladoc for details)This method is deprecated in 2.13 because it does not provide any actionable information. As noted above, even the collection library itself does not use it. When there is no guarantee that a collection is finite, it is generally best to attempt a computation anyway and document that it will not terminate for infinite collections rather than backing out because this would prevent performing the computation on collections that are in fact finite even though
hasDefiniteSizereturnsfalse.- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Attributes
- Deprecated
[Since version 2.13.0]Use coll instead of repr in a collection implementation, use the collection value itself from the outside- Inherited from:
- IterableOps
- Source
- Iterable.scala
Attributes
- Deprecated
[Since version 2.13.0]Iterable.seq always returns the iterable itself- Inherited from:
- Iterable
- Source
- Iterable.scala
Attributes
- Returns
This collection as an
Iterable[A]. No new collection will be built ifthisis already anIterable[A].- Deprecated
[Since version 2.13.7]toIterable is internal and will be made protected; its name is similar to `toList` or `toSeq`, but it doesn\'t copy non-immutable collections- Inherited from:
- Iterable
- Source
- Iterable.scala
Attributes
- Deprecated
[Since version 2.13.0]Use .iterator instead of .toIterator- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Attributes
- Deprecated
[Since version 2.13.0]Use .to(LazyList) instead of .toStream- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Converts this iterable collection to an unspecified Iterable.
Converts this iterable collection to an unspecified Iterable. Will return the same collection if this instance is already Iterable.
Attributes
- Returns
An Iterable containing all elements of this iterable collection.
- Deprecated
[Since version 2.13.0]toTraversable is internal and will be made protected; its name is similar to `toList` or `toSeq`, but it doesn\'t copy non-immutable collections- Inherited from:
- IterableOps
- Source
- Iterable.scala
A view over a slice of the elements of this collection.
A view over a slice of the elements of this collection.
Attributes
- Deprecated
[Since version 2.13.0]Use .view.slice(from, until) instead of .view(from, until)- Inherited from:
- IterableOps
- Source
- Iterable.scala