AbstractMapView (original) (raw)
Appends all elements of this collection to a string builder.
Appends all elements of this collection to a string builder. The written text consists of the string representations (w.r.t. the method toString) of all elements of this collection without any separator string.
Example:
scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)
scala> val b = new StringBuilder()
b: StringBuilder =
scala> val h = a.addString(b)
h: StringBuilder = 1234
Value parameters
b
the string builder to which elements are appended.
Attributes
Returns
the string builder b to which elements were appended.
Inherited from:
Source
Appends all elements of this collection to a string builder using a separator string.
Appends all elements of this collection to a string builder using a separator string. The written text consists of the string representations (w.r.t. the method toString) of all elements of this collection, separated by the string sep.
Example:
scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)
scala> val b = new StringBuilder()
b: StringBuilder =
scala> a.addString(b, ", ")
res0: StringBuilder = 1, 2, 3, 4
Value parameters
b
the string builder to which elements are appended.
sep
the separator string.
Attributes
Returns
the string builder b to which elements were appended.
Inherited from:
Source
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 string start and ends with the string end. Inside, the string representations (w.r.t. the method toString) of all elements of this map are separated by the string sep.
Example:
scala> val a = List(1,2,3,4)
a: List[Int] = List(1, 2, 3, 4)
scala> val b = new StringBuilder()
b: StringBuilder =
scala> a.addString(b , "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
Returns
the string builder b to which elements were appended.
Definition Classes
Inherited from:
Source
Composes this partial function with another partial function that gets applied to results of this partial function.
Composes this partial function with another partial function that gets applied to results of this partial function.
Note that calling isDefinedAt on the resulting partial function may apply the first partial function and execute its side effect. For efficiency, it is recommended to call applyOrElse instead of isDefinedAt or apply.
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 x to k(this(x)).
Inherited from:
Source
Composes this partial function with a transformation function that gets applied to results of this partial function.
Composes this partial function with a transformation function that gets applied to results of this partial function.
If the runtime type of the function is a PartialFunction then the other andThen method is used (note its cautions).
Type parameters
C
the result type of the transformation function.
Value parameters
k
the transformation function
Attributes
Returns
a partial function with the domain of this partial function, possibly narrowed by the specified function, which maps arguments x to k(this(x)).
Definition Classes
Inherited from:
Source
Retrieves the value which is associated with the given key.
Retrieves the value which is associated with the given key. This method invokes the default method of the map if there is no mapping from the given key to a value. Unless overridden, the default method throws a NoSuchElementException.
Value parameters
key
the key
Attributes
Returns
the value associated with the given key, or the result of the map's default method, if none exists.
Inherited from:
Source
Applies this partial function to the given argument when it is contained in the function domain.
Applies this partial function to the given argument when it is contained in the function domain. Applies fallback function where this partial function is not defined.
Note that expression pf.applyOrElse(x, default) is equivalent to
if(pf isDefinedAt x) pf(x) else default(x)
except that applyOrElse method can be implemented more efficiently. For all partial function literals the compiler generates an applyOrElse implementation which avoids double evaluation of pattern matchers and guards. This makes applyOrElse the basis for the efficient implementation for many operations and scenarios, such as:
- combining partial functions into orElse/andThen chains does not lead to excessive apply/isDefinedAt evaluation - lift and unlift do not evaluate source functions twice on each invocation - runWith allows efficient imperative-style combining of partial functions with conditionally applied actions
For non-literal partial function classes with nontrivial isDefinedAt method it is recommended to override applyOrElse with custom implementation that avoids double isDefinedAt evaluation. This may result in better performance and more predictable behavior w.r.t. side effects.
Value parameters
default
the fallback function
x
the function argument
Attributes
Returns
the result of this function or fallback function application.
Definition Classes
Inherited from:
Source
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 pf to each element on which it is defined and collecting the results. The order of the elements is preserved.
Inherited from:
Source
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
Returns
a new map resulting from applying the given partial function pf to each element on which it is defined and collecting the results. The order of the elements is preserved.
Inherited from:
Source
Finds the first element of the collection for which the given partial function is defined, and applies the partial function to it.
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 None if none exists.
Example
Seq("a", 1, 5L).collectFirst({ case x: Int => x*10 }) = Some(10)
Inherited from:
Source
Composes another partial function k with this partial function so that this partial function gets applied to results of k.
Composes another partial function k with this partial function so that this partial function gets applied to results of k.
Note that calling isDefinedAt on the resulting partial function may apply the first partial function and execute its side effect. For efficiency, it is recommended to call applyOrElse instead of isDefinedAt or apply.
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 x to this(k(x)).
Inherited from:
Source
Composes two instances of Function1 in a new Function1, with this function applied last.
Composes two instances of Function1 in a new Function1, with this function applied last.
Type parameters
A
the type to which function g can be applied
Value parameters
g
a function A => T1
Attributes
Returns
a new function f such that f(x) == apply(g(x))
Inherited from:
Source
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:
Source
Returns a new map containing the elements from the left hand operand followed by the elements from the right hand operand.
Returns a new map containing the elements from the left hand operand followed by the elements from the right hand operand. The element type of the map is the most specific superclass encompassing the element types of the two operands.
Value parameters
suffix
the iterable to append.
Attributes
Returns
a new map which contains all elements of this map followed by all elements of suffix.
Inherited from:
Source
Tests whether this map contains a binding for a key.
Tests whether this map contains a binding for a key.
Value parameters
key
the key
Attributes
Returns
true if there is a binding for key in this map, false otherwise.
Inherited from:
Source
Copy elements to an array, returning the number of elements written.
Copy elements to an array, returning the number of elements written.
Fills the given array xs starting at index start with at most len elements of this collection.
Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached, or len elements have been copied.
Type parameters
B
the type of the elements of the array.
Value parameters
len
the maximal number of elements to copy.
start
the starting index of xs.
xs
the array to fill.
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:
Source
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 array xs starting at index start with values of this collection.
Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached.
Type parameters
B
the type of the elements of the array.
Value parameters
start
the starting index of xs.
xs
the array to fill.
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:
Source
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 array xs starting at index start with values of this collection.
Copying will stop once either all the elements of this collection have been copied, or the end of the array is reached.
Type parameters
B
the type of the elements of the array.
Value parameters
xs
the array to fill.
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:
Source
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
true if both collections have the same length and p(x, y) is true for all corresponding elements x of this iterator and y of that, otherwise false
Inherited from:
Source
Counts the number of elements in the collection which satisfy a predicate.
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:
Source
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
Inherited from:
Source
Selects all elements except the first n ones.
Selects all elements except the first n ones.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parameters
n
the number of elements to drop from this iterable collection.
Attributes
Returns
a iterable collection consisting of all elements of this iterable collection except the first n ones, or else the empty iterable collection, if this iterable collection has less than n elements. If n is negative, don't drop any elements.
Inherited from:
Source
Selects all elements except last n ones.
Selects all elements except last n ones.
Note: might return different results for different runs, unless the underlying collection type is ordered.
Value parameters
n
the number of elements to drop from this iterable collection.
Attributes
Returns
a iterable collection consisting of all elements of this iterable collection except the last n ones, or else the empty iterable collection, if this iterable collection has less than n elements. If n is negative, don't drop any elements.
Inherited from:
Source
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)
Use span to obtain both the prefix and suffix. Use filterNot 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:
Source
Returns an extractor object with a unapplySeq method, which extracts each element of a sequence data.
Returns an extractor object with a unapplySeq method, which extracts each element of a sequence data.
Attributes
Example
val firstChar: String => Option[Char] = _.headOption
Seq("foo", "bar", "baz") match {
case firstChar.unlift.elementWise(c0, c1, c2) =>
println(s"$c0, <span class="katex"><span class="katex-mathml"><math xmlns="http://www.w3.org/1998/Math/MathML"><semantics><mrow><mi>c</mi><mn>1</mn><mo separator="true">,</mo></mrow><annotation encoding="application/x-tex">c1, </annotation></semantics></math></span><span class="katex-html" aria-hidden="true"><span class="base"><span class="strut" style="height:0.8389em;vertical-align:-0.1944em;"></span><span class="mord mathnormal">c</span><span class="mord">1</span><span class="mpunct">,</span></span></span></span>c2") // Output: f, b, b
}
Inherited from:
Source
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:
Source
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
true if the given predicate p is satisfied by at least one element of this collection, otherwise false
Inherited from:
Source
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:
Source
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:
Source
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:
Source
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, or None if none exists.
Inherited from:
Source
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 Set
def lettersOf(words: Seq[String]) = words flatMap (word => word.toSet)
// lettersOf will return a Set[Char], not a Seq
def lettersOf(words: Seq[String]) = words.toSet flatMap ((word: 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 f to each element of this iterable collection and concatenating the results.
Inherited from:
Source
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
Returns
a new map resulting from applying the given collection-valued function f to each element of this map and concatenating the results.
Inherited from:
Source
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:
Source
Applies the given binary operator op to the given initial value z and all elements of this collection.
Applies the given binary operator op to the given initial value z 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 for List concatenation or 1 for multiplication.
The default implementation in IterableOnce is equivalent to foldLeft 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 op for the result to always be the same across runs.
Attributes
Returns
The result of applying op between all the elements and z, or z if this collection is empty.
Inherited from:
Source
Applies the given binary operator op to the given initial value z and all elements of this collection, going left to right.
Applies the given binary operator op to the given initial value z 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 if x1, x2, ..., xn are the elements of this collection, the result is op( 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 op to z and all elements of this collection, going left to right. Returns z if this collection is empty.
Inherited from:
Source
Applies the given binary operator op to all elements of this collection and the given initial value z, going right to left.
Applies the given binary operator op to all elements of this collection and the given initial value z, 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 if x1, x2, ..., xn are the elements of this collection, the result is op(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 op to all elements of this collection and z, going right to left. Returns z if this collection is empty.
Inherited from:
Source
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
true if this collection is empty or the given predicate p holds for all elements of this collection, otherwise false.
Inherited from:
Source
Applies f to each element for its side effects.
Applies f to each element for its side effects. Note: U parameter needed to help scalac's type inference.
Attributes
Inherited from:
Source
Apply f to each key/value pair for its side effects Note: [U] parameter needed to help scalac's type inference.
Apply f to each key/value pair for its side effects Note: [U] parameter needed to help scalac's type inference.
Attributes
Inherited from:
Source
Defines how to turn a given Iterable[A] into a collection of type C.
Defines how to turn a given Iterable[A] into a collection of type C.
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 C to the new type, this method needs to be overridden (the compiler will issue an error otherwise). In the common case where C =:= CC[A], this can be done by mixing in the scala.collection.IterableFactoryDefaults trait, which implements the method using iterableFactory.
As witnessed by the @uncheckedVariance annotation, using this method might be unsound. However, as long as it is called with an Iterable[A] obtained from this collection (as it is the case in the implementations of operations where we use a View[A]), it is safe.
Inherited from:
Source
Returns the value associated with a key, or a default value if the key is not contained in the map.
Returns the value associated with a key, or a default value if the key is not contained in the map.
Type parameters
V1
the result type of the default computation.
Value parameters
default
a computation that yields a default value in case no binding for key is found in the map.
key
the key.
Attributes
Returns
the value associated with key if it exists, otherwise the result of the default computation.
Inherited from:
Source
Partitions this iterable collection into a map of iterable collections according to some discriminator function.
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 k is bound to a iterable collection of those elements x for which f(x) equals k.
Inherited from:
Source
Partitions this iterable collection into a map of iterable collections according to a discriminator function key.
Partitions this iterable collection into a map of iterable collections according to a discriminator function key. Each element in a group is transformed into a value of type B using the value function.
It is equivalent to groupBy(key).mapValues(_.map(f)), but more efficient.
case class User(name: String, age: Int)
def namesByAge(users: Seq[User]): Map[Int, Seq[String]] =
users.groupMap(_.age)(_.name)
Note: Even when applied to a view or a lazy collection it will always force the elements.
Type 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:
Source
Partitions this iterable collection into a map according to a discriminator function key.
Partitions this iterable collection into a map according to a discriminator function key. All the values that have the same discriminator are then transformed by the f function and then reduced into a single value with the reduce function.
It is equivalent to groupBy(key).mapValues(_.map(f).reduce(reduce)), but more efficient.
def occurrences[A](as: Seq[A]): Map[A, Int] =
as.groupMapReduce(identity)(_ => 1)(_ + _)
Note: Even when applied to a view or a lazy collection it will always force the elements.
Attributes
Inherited from:
Source
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 size size if the elements don't divide evenly.
See also
Inherited from:
Source
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
Inherited from:
Source
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, None if it is empty.
Inherited from:
Source
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:
Source
Iterates over the inits of this iterable collection.
Iterates over the inits of this iterable collection. The first value will be this iterable collection and the final one will be an empty iterable collection, with the intervening values the results of successive applications of init.
Note: Even when applied to a view or a lazy collection it will always force the elements.
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:
Source
Tests whether this map contains a binding for a key.
Tests whether this map contains a binding for a key. This method, which implements an abstract method of trait PartialFunction, is equivalent to contains.
Value parameters
key
the key
Attributes
Returns
true if there is a binding for key in this map, false otherwise.
Inherited from:
Source
Tests whether the collection is empty.
Tests whether the collection 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 when isEmpty is called.
Attributes
Returns
true if the collection contains no elements, false otherwise.
Inherited from:
Source
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
true if it is repeatedly traversable, false otherwise.
Definition Classes
Inherited from:
Source
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 CC to 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:
Source
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.toSet - To obtain a view on the keys, use
scala.collection.View.fromIteratorProvider(m.keysIterator)
Attributes
Returns
a set representing the keys contained by this map
Inherited from:
Source
Returns a Stepper for the keys of this map.
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:
Source
An Iterator of the keys contained by this map.
The number of elements in this collection, if it can be cheaply computed, -1 otherwise.
The number of elements in this collection, if it can be cheaply computed, -1 otherwise. Cheaply usually means: Not requiring a collection traversal.
Attributes
Inherited from:
Source
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
Inherited from:
Source
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, None if it is empty.
Inherited from:
Source
Analogous to zip except that the elements in each collection are not consumed until a strict operation is invoked on the returned LazyZip2 decorator.
Analogous to zip except that the elements in each collection are not consumed until a strict operation is invoked on the returned LazyZip2 decorator.
Calls to lazyZip can be chained to support higher arities (up to 4) without incurring the expense of constructing and deconstructing intermediary tuples.
val xs = List(1, 2, 3)
val res = (xs lazyZip xs lazyZip xs lazyZip xs).map((a, b, c, d) => a + b + c + d)
// res == List(4, 8, 12)
Type parameters
B
the type of the second element in each eventual pair
Value parameters
that
the iterable providing the second element of each eventual pair
Attributes
Returns
a decorator LazyZip2 that allows strict operations to be performed on the lazily evaluated pairs or chained calls to lazyZip. Implicit conversion to Iterable[(A, B)] is also supported.
Inherited from:
Source
Turns this partial function into a plain function returning an Option result.
Turns this partial function into a plain function returning an Option result.
Attributes
Returns
a function that takes an argument x to Some(this(x)) if this is defined for x, and to None otherwise.
See also
Inherited from:
Source
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 f to each element of this iterable collection and collecting the results.
Inherited from:
Source
Builds a new map by applying a function to all elements of this map.
Builds a new map by applying a function to all elements of this map.
Value parameters
f
the function to apply to each element.
Attributes
Returns
a new map resulting from applying the given function f to each element of this map and collecting the results.
Inherited from:
Source
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 CC to 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:
Source
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:
Source
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
Inherited from:
Source
Finds the first element which yields the largest value measured by function f.
Finds the first element which yields the largest value measured by function f.
Note: will not terminate for infinite-sized collections.
Type parameters
B
The result type of the function f.
Value parameters
cmp
An ordering to be used for comparing elements.
f
The measuring function.
Attributes
Returns
the first element of this collection with the largest value measured by function f with respect to the ordering cmp.
Throws
Inherited from:
Source
Finds the first element which yields the largest value measured by function f.
Finds the first element which yields the largest value measured by function f.
Note: will not terminate for infinite-sized collections.
Type parameters
B
The result type of the function f.
Value parameters
cmp
An ordering to be used for comparing elements.
f
The measuring function.
Attributes
Returns
an option value containing the first element of this collection with the largest value measured by function f with respect to the ordering cmp.
Inherited from:
Source
Finds the largest element.
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:
Source
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
Inherited from:
Source
Finds the first element which yields the smallest value measured by function f.
Finds the first element which yields the smallest value measured by function f.
Note: will not terminate for infinite-sized collections.
Type parameters
B
The result type of the function f.
Value parameters
cmp
An ordering to be used for comparing elements.
f
The measuring function.
Attributes
Returns
the first element of this collection with the smallest value measured by function f with respect to the ordering cmp.
Throws
Inherited from:
Source
Finds the first element which yields the smallest value measured by function f.
Finds the first element which yields the smallest value measured by function f.
Note: will not terminate for infinite-sized collections.
Type parameters
B
The result type of the function f.
Value parameters
cmp
An ordering to be used for comparing elements.
f
The measuring function.
Attributes
Returns
an option value containing the first element of this collection with the smallest value measured by function f with respect to the ordering cmp.
Inherited from:
Source
Finds the smallest element.
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:
Source
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:
Source
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 string sep.
Example
List(1, 2, 3).mkString("|") = "1|2|3"
Inherited from:
Source
Displays all elements of this collection in a string using start, end, and separator strings.
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 start and ends with the string end. Inside, the string representations (w.r.t. the method toString) of all elements of this collection are separated by the string sep.
Example
List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"
Inherited from:
Source
Attributes
Returns
a strict builder for the same collection type. Note that in the case of lazy collections (e.g. scala.collection.View or scala.collection.immutable.LazyList), it is possible to implement this method but the resulting Builder will break laziness. As a consequence, operations should preferably be implemented with fromSpecific instead of this method.
Note
When implementing a custom collection type and refining C to the new type, this method needs to be overridden (the compiler will issue an error otherwise). In the common case where C =:= CC[A], this can be done by mixing in the scala.collection.IterableFactoryDefaults trait, which implements the method using iterableFactory.
As witnessed by the @uncheckedVariance annotation, using this method might be unsound. However, as long as the returned builder is only fed with A values taken from this instance, it is safe.
Inherited from:
Source
Tests whether the collection is not empty.
Tests whether the collection is not empty.
Attributes
Returns
true if the collection contains at least one element, false otherwise.
Inherited from:
Source
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 takes x to this(x) where this is defined, and to that(x) where it is not.
Inherited from:
Source
A pair of, first, all elements that satisfy predicate p and, second, all elements that do not.
A pair of, first, all elements that satisfy predicate p and, second, all elements that do not. Interesting because it splits a collection in two.
The default implementation provided here needs to traverse the collection twice. Strict collections have an overridden version of partition in StrictOptimizedIterableOps, which requires only a single traversal.
Attributes
Definition Classes
Inherited from:
Source
Applies a function f to each element of the iterable collection and returns a pair of iterable collections: the first one made of those values returned by f that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.
Applies a function f to each element of the iterable collection and returns a pair of iterable collections: the first one made of those values returned by f that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.
Example:
val xs = Iterable(1, "one", 2, "two", 3, "three") partitionMap {
case i: Int => Left(i)
case s: String => Right(s)
}
// xs == (Iterable(1, 2, 3),
// Iterable(one, two, three))
Type parameters
A1
the element type of the first resulting collection
A2
the element type of the second resulting collection
Value parameters
f
the 'split function' mapping the elements of this iterable collection to an scala.util.Either
Attributes
Returns
a pair of iterable collections: the first one made of those values returned by f that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.
Inherited from:
Source
Multiplies together the elements of this collection.
Multiplies together the elements of this collection.
The default implementation uses reduce 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 in num.
Inherited from:
Source
Applies the given binary operator op to all elements of this collection.
Applies the given binary operator op 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 op between all the elements if the collection is nonempty.
Throws
Inherited from:
Source
Applies the given binary operator op to all elements of this collection, going left to right.
Applies the given binary operator op to all elements of this collection, going left to right.
"Going left to right" only makes sense if this collection is ordered: then if x1, x2, ..., xn are the elements of this collection, the result is op( 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 op to all elements of this collection, going left to right.
Throws
Inherited from:
Source
If this collection is nonempty, reduces it with the given binary operator op, going left to right.
If this collection is nonempty, reduces it with the given binary operator op, going left to right.
The behavior is the same as reduceLeft except that the value is None 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 op going left to right if the collection is nonempty, inside a Some, and None otherwise.
Inherited from:
Source
If this collection is nonempty, reduces it with the given binary operator op.
If this collection is nonempty, reduces it with the given binary operator op.
The behavior is the same as reduce except that the value is None 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 op if the collection is nonempty, inside a Some, and None otherwise.
Inherited from:
Source
Applies the given binary operator op to all elements of this collection, going right to left.
Applies the given binary operator op to all elements of this collection, going right to left.
"Going right to left" only makes sense if this collection is ordered: then if x1, x2, ..., xn are the elements of this collection, the result is op(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 op to all elements of this collection, going right to left.
Throws
Inherited from:
Source
If this collection is nonempty, reduces it with the given binary operator op, going right to left.
If this collection is nonempty, reduces it with the given binary operator op, going right to left.
The behavior is the same as reduceRight except that the value is None 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 op going right to left if the collection is nonempty, inside a Some, and None otherwise.
Inherited from:
Source
Composes this partial function with an action function which gets applied to results of this partial function.
Composes this partial function with an action function which gets applied to results of this partial function. The action function is invoked only for its side effects; its result is ignored.
Note that expression pf.runWith(action)(x) is equivalent to
if(pf isDefinedAt x) { action(pf(x)); true } else false
except that runWith is implemented via applyOrElse and thus potentially more efficient. Using runWith avoids double evaluation of pattern matchers and guards for partial function literals.
Value parameters
action
the action function
Attributes
Returns
a function which maps arguments x to isDefinedAt(x). The resulting function runs action(this(x)) where this is defined.
See also
Inherited from:
Source
Computes a prefix scan of the elements of the collection.
Computes a prefix scan of the elements of the collection.
Note: The neutral element z may be applied more than once.
Type parameters
B
element type of the resulting collection
Value parameters
op
the associative operator for the scan
z
neutral element for the operator op
Attributes
Returns
a new iterable collection containing the prefix scan of the elements in this iterable collection
Inherited from:
Source
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:
Source
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:
Source
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:
Source
Compares the size of this iterable collection to the size of another Iterable.
Compares the size of this iterable collection to the size of another Iterable.
Value parameters
that
the Iterable whose size is compared with this iterable collection's size.
Attributes
Returns
A value x where
x < 0 if this.size < that.size
x == 0 if this.size == that.size
x > 0 if this.size > that.size
The method as implemented here does not call size directly; its running time is O(this.size min that.size) instead of O(this.size + that.size). The method should be overridden if computing size is cheap and knownSize returns -1.
Inherited from:
Source
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 x where
x < 0 if this.size < otherSize
x == 0 if this.size == otherSize
x > 0 if this.size > otherSize
The method as implemented here does not call size directly; its running time is O(size min otherSize) instead of O(size). The method should be overridden if computing size is cheap and knownSize returns -1.
See also
Inherited from:
Source
Returns a value class containing operations for comparing the size of this iterable collection to a test value.
Returns a value class containing operations for comparing the size of this iterable collection to a test value.
These operations are implemented in terms of sizeCompare(Int), and allow the following more readable usages:
this.sizeIs < size // this.sizeCompare(size) < 0
this.sizeIs <= size // this.sizeCompare(size) <= 0
this.sizeIs == size // this.sizeCompare(size) == 0
this.sizeIs != size // this.sizeCompare(size) != 0
this.sizeIs >= size // this.sizeCompare(size) >= 0
this.sizeIs > size // this.sizeCompare(size) > 0
Attributes
Inherited from:
Source
Selects an interval of elements.
Selects an interval of elements. The returned iterable 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.
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 from extending up to (but not including) index until of this iterable collection.
Inherited from:
Source
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 than size elements remaining to be grouped.
See also
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:
Source
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)
An empty collection returns an empty iterator, and a non-empty collection containing fewer elements than the window size returns an iterator that will produce the original collection as its only element.
Value parameters
size
the number of elements per group
Attributes
Returns
An iterator producing iterable collections of size size, except for a non-empty collection with less than size elements, which returns an iterator that produces the source collection itself as its only element.
See also
Example
List().sliding(2) = empty iterator
List(1).sliding(2) = Iterator(List(1))
List(1, 2).sliding(2) = Iterator(List(1, 2))
List(1, 2, 3).sliding(2) = Iterator(List(1, 2), List(2, 3))
Inherited from:
Source
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 predicate p 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:
Source
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 n elements of this iterable collection, and the other elements.
Definition Classes
Inherited from:
Source
Returns a scala.collection.Stepper for the elements of this collection.
The Stepper enables creating a Java stream to operate on the collection, see scala.jdk.StreamConverters. For collections holding primitive values, the Stepper can be used as an iterator which doesn't box the elements.
The implicit scala.collection.StepperShape parameter defines the resulting Stepper type according to the element type of this collection.
- For collections of
Int,Short,ByteorChar, an scala.collection.IntStepper is returned - For collections of
DoubleorFloat, a scala.collection.DoubleStepper is returned - For collections of
Longa scala.collection.LongStepper is returned - For any other element type, an scala.collection.AnyStepper is returned
Note that this method is overridden in subclasses and the return type is refined to S with EfficientSplit, for example scala.collection.IndexedSeqOps.stepper. For Steppers marked with scala.collection.Stepper.EfficientSplit, the converters in scala.jdk.StreamConverters allow creating parallel streams, whereas bare Steppers can be converted only to sequential streams.
Attributes
Inherited from:
Source
Sums the elements of this collection.
Sums the elements of this collection.
The default implementation uses reduce 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 in num.
Inherited from:
Source
The rest of the collection without its first element.
Iterates over the tails of this iterable collection.
Iterates over the tails of this iterable collection. The first value will be this iterable collection and the final one will be an empty iterable collection, with the intervening values the results of successive applications of tail.
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)
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Selects the first n elements.
Selects the first n 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 n elements of this iterable collection, or else the whole iterable collection, if it has less than n elements. If n is negative, returns an empty iterable collection.
Inherited from:
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Selects the last n elements.
Selects the last n 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 n elements of this iterable collection, or else the whole iterable collection, if it has less than n elements. If n is negative, returns an empty iterable collection.
Inherited from:
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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:
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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 apply f to their elements immediately, while lazy collections like Views and LazyLists will only apply f 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:
Source
Given a collection factory factory, converts this collection to the appropriate representation for the current element type A.
Given a collection factory factory, converts this collection to the appropriate representation for the current element type A. Example uses:
xs.to(List)
xs.to(ArrayBuffer)
xs.to(BitSet) // for xs: Iterable[Int]
Attributes
Inherited from:
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Converts this collection to an Array.
Converts this collection to an Array.
Implementation note: DO NOT call Array.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:
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Converts this collection to a Buffer.
Converts this collection to a Buffer.
Type parameters
B
The type of elements of the result, a supertype of A.
Attributes
Returns
This collection as a Buffer[B].
Inherited from:
Source
Converts this collection to an IndexedSeq.
Converts this collection to a List.
Converts this collection to a Map, given an implicit coercion from the collection's type to a key-value tuple.
Converts this collection to a Map, 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 A to [K, V].
Attributes
Returns
This collection as a Map[K, V].
Inherited from:
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Converts this collection to a Set.
Converts this collection to a Set.
Type parameters
B
The type of elements of the result, a supertype of A.
Attributes
Returns
This collection as a Set[B].
Inherited from:
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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 className of this view, followed by all elements separated by commas and enclosed in parentheses.
Definition Classes
Inherited from:
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Converts this collection to a Vector.
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 as _n_th row the _n_th column of this iterable collection.
Throws
Inherited from:
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Tries to extract a B from an A in a pattern matching expression.
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:
Source
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:
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Returns a Stepper for the values of this map.
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:
Source
Creates an iterator for all values in this map.
Creates an iterator for all values in this map.
Attributes
Returns
an iterator over all values that are associated with some key in this map.
Inherited from:
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A view over the elements of this collection.
A view over the elements of this collection.
Attributes
Definition Classes
Inherited from:
Source
Creates a non-strict filter of this view.
Creates a non-strict filter of this view.
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.
Value parameters
p
the predicate used to test elements.
Attributes
Returns
an object of class WithFilter, which supports map, flatMap, foreach, and withFilter operations. All these operations apply to those elements of this view which satisfy the predicate p.
Definition Classes
Inherited from:
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Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs.
Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs. If one of the two collections is 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 and that.
Inherited from:
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Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs.
Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs. If one of the two collections is shorter than the other, placeholder elements are used to extend the shorter collection to the length of the longer.
Value parameters
that
the iterable providing the second half of each result pair
thatElem
the element to be used to fill up the result if that is shorter than this iterable collection.
thisElem
the element to be used to fill up the result if this iterable collection is shorter than that.
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 and that. If this iterable collection is shorter than that, thisElem values are used to pad the result. If that is shorter than this iterable collection, thatElem values are used to pad the result.
Inherited from:
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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:
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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 key in this map, or None if none exists.
Inherited from:
Source
Attributes
Deprecated
[Since version 2.13.0] Use ++ with an explicit collection argument instead of + with varargs
Inherited from:
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Attributes
Deprecated
[Since version 2.13.0] Consider requiring an immutable Map or fall back to Map.concat.
Inherited from:
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Attributes
Deprecated
[Since version 2.13.0] Use ++ instead of ++: for collections of type Iterable
Inherited from:
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Attributes
Deprecated
[Since version 2.13.0] Use ++ instead of ++: for collections of type Iterable
Inherited from:
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Attributes
Deprecated
[Since version 2.13.0] Consider requiring an immutable Map.
Inherited from:
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Aggregates the results of applying an operator to subsequent elements.
Aggregates the results of applying an operator to subsequent elements.
Since this method degenerates to foldLeft for sequential (non-parallel) collections, where the combining operation is ignored, it is advisable to prefer foldLeft for that case.
For parallel collections, use the aggregate method specified by scala.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:
Source
Attributes
Deprecated
[Since version 2.13.0] Views no longer know about their underlying collection type; .force always returns an IndexedSeq
Inherited from:
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Tests whether this collection is known to have a finite size.
Tests whether this collection is known to have a finite size. All strict collections are known to have finite size. For a non-strict collection such as Stream, the predicate returns **true** if all elements have been computed. It returns **false** if the stream is not yet evaluated to the end. Non-empty Iterators usually return **false** even if they were created from a collection with a known finite size.
Note: many collection methods will not work on collections of infinite sizes. The typical failure mode is an infinite loop. These methods always attempt a traversal without checking first that hasDefiniteSize returns **true**. However, checking hasDefiniteSize can provide an assurance that size is well-defined and non-termination is not a concern.
Attributes
Returns
**true** if this collection is known to have finite size, **false** otherwise.
See also
method knownSize for 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 hasDefiniteSize returns false.
Inherited from:
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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:
Source
Attributes
Deprecated
[Since version 2.13.0] Iterable.seq always returns the iterable itself
Inherited from:
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Attributes
Returns
This collection as an Iterable[A]. No new collection will be built if this is already an Iterable[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:
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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:
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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:
Source