Base trait for immutable set collections
Attributes
Members list
Value members
Concrete methods
The companion object of this immutable set, providing various factory methods.
The companion object of this immutable set, 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
- Source
- Set.scala
Inherited methods
Alias for concat
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
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 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
bto which elements were appended. - Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Appends all elements of this collection to a string builder using start, end, and separator strings.
Appends all elements of this collection 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 collection 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
bto which elements were appended. - Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Composes two instances of Function1 in a new Function1, with this function applied first.
Composes two instances of Function1 in a new Function1, with this function applied first.
Type parameters
- A
-
the result type of function
g
Value parameters
- g
-
a function R => A
Attributes
- Returns
-
a new function
fsuch thatf(x) == g(apply(x)) - Inherited from:
- Function1
- Source
- Function1.scala
Tests if some element is contained in this set.
Tests if some element is contained in this set.
This method is equivalent to contains. It allows sets to be interpreted as predicates.
Value parameters
- elem
-
the element to test for membership.
Attributes
Checks whether this instance can possibly equal that.
Checks whether this instance can possibly equal that.
A method that should be called from every well-designed equals method that is open to be overridden in a subclass. See Programming in Scala, Chapter 28 for discussion and design.
Value parameters
- that
-
the value being probed for possible equality
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
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 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
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
Creates a new set by adding all elements contained in another collection to this set, omitting duplicates.
Creates a new set by adding all elements contained in another collection to this set, omitting duplicates.
This method takes a collection of elements and adds all elements, omitting duplicates, into set.
Example:
scala> val a = Set(1, 2) concat Set(2, 3)
a: scala.collection.immutable.Set[Int] = Set(1, 2, 3)
Value parameters
- that
-
the collection containing the elements to add.
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 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:
- 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 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:
- 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 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:
- 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
Computes the difference of this set and another set.
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
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 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
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)
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:
- IterableOps
- Source
- Iterable.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:
- IterableFactoryDefaults
- Source
- Iterable.scala
Equality of sets is implemented using the lookup method contains.
Equality of sets is implemented using the lookup method contains. This method returns true if
-
the argument
thatis aSet, -
the two sets have the same size, and
-
for every
elementthis set,other.contains(element) == true.
The implementation of equals checks the canEqual method, so subclasses of Set can narrow down the equality to specific set types. The Set implementations in the standard library can all be compared, their canEqual methods return true.
Note: The equals method only respects the equality laws (symmetry, transitivity) if the two sets use the same element equivalence function in their lookup operation. For example, the element equivalence operation in a scala.collection.immutable.TreeSet is defined by its ordering. Comparing a TreeSet with a HashSet leads to unexpected results if ordering.equiv(e1, e2) (used for lookup in TreeSet) is different from e1 == e2 (used for lookup in HashSet).
scala> import scala.collection.immutable._
scala> val ord: Ordering[String] = _ compareToIgnoreCase _
scala> TreeSet("A")(ord) == HashSet("a")
val res0: Boolean = false
scala> HashSet("a") == TreeSet("A")(ord)
val res1: Boolean = true
Value parameters
- that
-
The set to which this set is compared
Attributes
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 iterable collection which satisfy a predicate.
Selects all elements of this iterable collection which satisfy a predicate.
Value parameters
- p
-
the predicate used to test elements.
Attributes
- Returns
-
a new iterable collection consisting of all elements of this iterable collection that satisfy the given predicate
p. The order of the elements is preserved. - Inherited from:
- IterableOps
- Source
- Iterable.scala
Selects all elements of this iterable collection which do not satisfy a predicate.
Selects all elements of this iterable collection which do not satisfy a predicate.
Value parameters
- pred
-
the predicate used to test elements.
Attributes
- Returns
-
a new iterable collection consisting of all elements of this iterable collection that do not satisfy the given predicate
pred. Their order may not be preserved. - Inherited from:
- IterableOps
- Source
- Iterable.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 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
fto each element of this iterable collection and concatenating the results. - Inherited from:
- IterableOps
- Source
- Iterable.scala
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 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
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 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
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 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
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
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:
- IterableOnceOps
- Source
- IterableOnce.scala
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
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 the scala.collection.IterableFactoryDefaults trait, which implements the method using iterableFactory.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
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 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:
- IterableOps
- Source
- Iterable.scala
Partitions this iterable collection into a map according to a discriminator function key.
Partitions this iterable collection into a map according to a discriminator function key. All the values that have the same discriminator are then transformed by the f function and then reduced into a single value with the reduce function.
It is equivalent to groupBy(key).mapValues(_.map(f).reduce(reduce)), but more efficient.
def occurrences[A](as: Seq[A]): Map[A, Int] =
as.groupMapReduce(identity)(_ => 1)(_ + _)
Note: Even when applied to a view or a lazy collection it will always force the elements.
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
Calculates a hash code value for the object.
Calculates a hash code value for the object.
The default hashing algorithm is platform dependent.
Note that it is allowed for two objects to have identical hash codes (o1.hashCode.equals(o2.hashCode)) yet not be equal (o1.equals(o2) returns false). A degenerate implementation could always return 0. However, it is required that if two objects are equal (o1.equals(o2) returns true) that they have identical hash codes (o1.hashCode.equals(o2.hashCode)). Therefore, when overriding this method, be sure to verify that the behavior is consistent with the equals method.
Attributes
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
-
NoSuchElementException if 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 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:
- IterableOps
- Source
- Iterable.scala
Computes the intersection between this set and another set.
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
-
trueif the collection contains no elements,falseotherwise. - Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
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 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:
- IterableOnce
- Source
- IterableOnce.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
-
NoSuchElementException If 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 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
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
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
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
-
UnsupportedOperationException if this collection is empty.
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Finds the first element which yields the largest value measured by function f.
Finds the first element which yields the largest value measured by function f.
Note: will not terminate for infinite-sized collections.
Type parameters
- B
-
The result type of the function
f.
Value parameters
- cmp
-
An ordering to be used for comparing elements.
- f
-
The measuring function.
Attributes
- Returns
-
the first element of this collection with the largest value measured by function
fwith respect to the orderingcmp. - Throws
-
UnsupportedOperationException if this collection is empty.
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Finds the first element which yields the largest value measured by function f.
Finds the first element which yields the largest value measured by function f.
Note: will not terminate for infinite-sized collections.
Type parameters
- B
-
The result type of the function
f.
Value parameters
- cmp
-
An ordering to be used for comparing elements.
- f
-
The measuring function.
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
-
UnsupportedOperationException if this collection is empty.
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Finds the first element which yields the smallest value measured by function f.
Finds the first element which yields the smallest value measured by function f.
Note: will not terminate for infinite-sized collections.
Type parameters
- B
-
The result type of the function
f.
Value parameters
- cmp
-
An ordering to be used for comparing elements.
- f
-
The measuring function.
Attributes
- Returns
-
the first element of this collection with the smallest value measured by function
fwith respect to the orderingcmp. - Throws
-
UnsupportedOperationException if this collection is empty.
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Finds the first element which yields the smallest value measured by function f.
Finds the first element which yields the smallest value measured by function f.
Note: will not terminate for infinite-sized collections.
Type parameters
- B
-
The result type of the function
f.
Value parameters
- cmp
-
An ordering to be used for comparing elements.
- f
-
The measuring function.
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 or scala.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 the scala.collection.IterableFactoryDefaults trait, which implements the method using iterableFactory.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
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
- Inherited from:
- IterableOps
- Source
- Iterable.scala
Applies a function f to each element of the iterable collection and returns a pair of iterable collections: the first one made of those values returned by f that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.
Applies a function f to each element of the iterable collection and returns a pair of iterable collections: the first one made of those values returned by f that were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right.
Example:
val xs = Iterable(1, "one", 2, "two", 3, "three") partitionMap {
case i: Int => Left(i)
case s: String => Right(s)
}
// xs == (Iterable(1, 2, 3),
// Iterable(one, two, three))
Type parameters
- A1
-
the element type of the first resulting collection
- A2
-
the element type of the second resulting collection
Value parameters
- f
-
the 'split function' mapping the elements of this iterable collection to an scala.util.Either
Attributes
- Returns
-
a pair of iterable collections: the first one made of those values returned by
fthat were wrapped in scala.util.Left, and the second one made of those wrapped in scala.util.Right. - Inherited from:
- IterableOps
- Source
- Iterable.scala
Multiplies 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 innum. - Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
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
opbetween all the elements if the collection is nonempty. - Throws
-
UnsupportedOperationException if this collection is empty.
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
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
opto all elements of this collection, going left to right. - Throws
-
UnsupportedOperationException if this collection is empty.
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
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
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 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
opif the collection is nonempty, inside aSome, andNoneotherwise. - Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
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
opto all elements of this collection, going right to left. - Throws
-
UnsupportedOperationException if this collection is empty.
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
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
opgoing right to left if the collection is nonempty, inside aSome, andNoneotherwise. - Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Creates a new immutable set from this immutable set by removing all elements of another collection.
Creates a new immutable set from this immutable set by removing all elements of another collection.
Value parameters
- that
-
the collection containing the elements to remove.
Attributes
Attributes
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Computes a prefix scan of the elements of the collection.
Computes a prefix scan of the elements of the collection.
Note: The neutral element z may be applied more than once.
Type parameters
- B
-
element type of the resulting collection
Value parameters
- op
-
the associative operator for the scan
- z
-
neutral element for the operator
op
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 another Iterable.
Compares the size of this iterable collection to the size of another Iterable.
Value parameters
- that
-
the
Iterablewhose size is compared with this iterable collection's size.
Attributes
- Returns
-
A value
xwherex < 0 if this.size < that.size x == 0 if this.size == that.size x > 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 < otherSize x == 0 if this.size == otherSize x > 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 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:
- IterableOps
- Source
- Iterable.scala
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
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 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 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 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:
- 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 a scala.collection.Stepper for the elements of this collection.
Returns a scala.collection.Stepper for the elements of this collection.
The Stepper enables creating a Java stream to operate on the collection, see scala.jdk.StreamConverters. For collections holding primitive values, the Stepper can be used as an iterator which doesn't box the elements.
The implicit scala.collection.StepperShape parameter defines the resulting Stepper type according to the element type of this collection.
-
For collections of
Int,Short,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:
- IterableOnce
- Source
- IterableOnce.scala
An iterator over all subsets of this set of the given size.
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 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 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) - Inherited from:
- IterableOps
- Source
- Iterable.scala
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
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 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
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 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 iterable collection
Attributes
- Returns
-
The same logical collection as this
- Definition Classes
- Inherited from:
- IterableOps
- Source
- Iterable.scala
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:
- IterableOnceOps
- Source
- IterableOnce.scala
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:
- IterableOnceOps
- Source
- IterableOnce.scala
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:
- IterableOnceOps
- Source
- IterableOnce.scala
Converts this collection to an IndexedSeq.
Converts this collection to an IndexedSeq.
Attributes
- Returns
-
This collection as an
IndexedSeq[A]. - Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Converts this collection to a List.
Converts this collection to a List.
Attributes
- Returns
-
This collection as a
List[A]. - Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
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
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 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:
- IterableOnceOps
- Source
- IterableOnce.scala
Converts this collection to a Vector.
Converts this collection to a Vector.
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 as nth row the nth column of this iterable collection.
- Throws
-
IllegalArgumentException if all collections in this iterable collection are not of the same size.
- Inherited from:
- IterableOps
- Source
- Iterable.scala
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
A view over the elements of this collection.
A view over the elements of this collection.
Attributes
- Inherited from:
- IterableOps
- Source
- Iterable.scala
Creates a non-strict filter of this iterable collection.
Creates a non-strict filter of this iterable collection.
Note: the difference between c filter p and c withFilter p is that the former creates a new collection, whereas the latter only restricts the domain of subsequent map, flatMap, foreach, and withFilter operations.
Note: might return different results for different runs, unless the underlying collection type is ordered.
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 iterable collection which satisfy the predicatep. - Inherited from:
- IterableOps
- Source
- Iterable.scala
Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs.
Returns a iterable collection formed from this iterable collection and another iterable collection by combining corresponding elements in pairs. If one of the two collections is longer than the other, its remaining elements are ignored.
Type parameters
- B
-
the type of the second half of the returned pairs
Value parameters
- that
-
The iterable providing the second half of each result pair
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 type
Thatcontaining pairs consisting of corresponding elements of this iterable collection andthat. 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
Inherited and Abstract methods
Creates a new set with a given element removed from this set.
Creates a new set with an additional element, unless the element is already present.
An scala.collection.Iterator over the elements of this collection.
An scala.collection.Iterator over the elements of this collection.
If an IterableOnce object is in fact an scala.collection.Iterator, this method always returns itself, in its current state, but if it is an scala.collection.Iterable, this method always returns a new scala.collection.Iterator.
Attributes
- Inherited from:
- IterableOnce
- Source
- IterableOnce.scala
Deprecated and Inherited methods
Attributes
- Deprecated
- true
- Inherited from:
- IterableOps
- Source
- Iterable.scala
Attributes
- Deprecated
- true
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Attributes
- Deprecated
- true
- 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 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
- true
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Attributes
- Deprecated
- true
- Inherited from:
- IterableOps
- Source
- Iterable.scala
Attributes
- Deprecated
- true
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.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 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
-
trueif this collection is known to have finite size,falseotherwise. - See also
-
method
knownSizefor a more useful alternative - Deprecated
-
This method is deprecated in 2.13 because it does not provide any actionable information. As noted above, even the collection library itself does not use it. When there is no guarantee that a collection is finite, it is generally best to attempt a computation anyway and document that it will not terminate for infinite collections rather than backing out because this would prevent performing the computation on collections that are in fact finite even though
hasDefiniteSizereturnsfalse. - Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Attributes
- Deprecated
- true
- Inherited from:
- IterableOps
- Source
- Iterable.scala
Attributes
- Deprecated
- true
- 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
- true
- Inherited from:
- Iterable
- Source
- Iterable.scala
Attributes
- Deprecated
- true
- Inherited from:
- IterableOnceOps
- Source
- IterableOnce.scala
Attributes
- Deprecated
- true
- 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
- true
- 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
- true
- Inherited from:
- IterableOps
- Source
- Iterable.scala