GenTraversableOnce
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package collection
Applies a binary operator to a start value and all elements of this collection or iterator, going left to right.
Applies a binary operator to a start value and all elements of this collection or iterator, going left to right.
Note: /: is alternate syntax for foldLeft; z /: xs is the same as
xs foldLeft z.
Examples:
Note that the folding function used to compute b is equivalent to that used to compute c.
scala> val a = List(1,2,3,4) a: List[Int] = List(1, 2, 3, 4) scala> val b = (5 /: a)(_+_) b: Int = 15 scala> val c = (5 /: a)((x,y) => x + y) c: Int = 15
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
the result type of the binary operator.
the start value.
the binary operator.
the result of inserting op between consecutive elements of this collection or iterator,
going left to right with the start value z on the left:
op(...op(op(z, x_1), x_2), ..., x_n)
where x1, ..., xn are the elements of this collection or iterator.
Applies a binary operator to all elements of this collection or iterator and a start value, going right to left.
Applies a binary operator to all elements of this collection or iterator and a start value, going right to left.
Note: :\ is alternate syntax for foldRight; xs :\ z is the same as
xs foldRight z.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
Examples:
Note that the folding function used to compute b is equivalent to that used to compute c.
scala> val a = List(1,2,3,4) a: List[Int] = List(1, 2, 3, 4) scala> val b = (a :\ 5)(_+_) b: Int = 15 scala> val c = (a :\ 5)((x,y) => x + y) c: Int = 15
the result type of the binary operator.
the start value
the binary operator
the result of inserting op between consecutive elements of this collection or iterator,
going right to left with the start value z on the right:
op(x_1, op(x_2, ... op(x_n, z)...))
where x1, ..., xn are the elements of this collection or iterator.
Aggregates the results of applying an operator to subsequent elements.
Aggregates the results of applying an operator to subsequent elements.
This is a more general form of fold and reduce. It is similar to
foldLeft in that it doesn't require the result to be a supertype of the
element type. In addition, it allows parallel collections to be processed
in chunks, and then combines the intermediate results.
aggregate splits the collection or iterator into partitions and processes each
partition by sequentially applying seqop, starting with z (like
foldLeft). Those intermediate results are then combined by using
combop (like fold). The implementation of this operation may operate
on an arbitrary number of collection partitions (even 1), so combop may
be invoked an arbitrary number of times (even 0).
As an example, consider summing up the integer values of a list of chars.
The initial value for the sum is 0. First, seqop transforms each input
character to an Int and adds it to the sum (of the partition). Then,
combop just needs to sum up the intermediate results of the partitions:
List('a', 'b', 'c').aggregate(0)({ (sum, ch) => sum + ch.toInt }, { (p1, p2) => p1 + p2 })
the type of accumulated results
the initial value for the accumulated result of the partition - this
will typically be the neutral element for the seqop operator (e.g.
Nil for list concatenation or 0 for summation) and may be evaluated
more than once
an operator used to accumulate results within a partition
an associative operator used to combine results from different partitions
Counts the number of elements in the collection or iterator which satisfy a predicate.
Counts the number of elements in the collection or iterator which satisfy a predicate.
the predicate used to test elements.
the number of elements satisfying the predicate p.
Tests whether a predicate holds for at least one element of this collection or iterator.
Tests whether a predicate holds for at least one element of this collection or iterator.
Note: may not terminate for infinite-sized collections.
the predicate used to test elements.
true if the given predicate p is satisfied by at least one element of this collection or iterator, otherwise false
Finds the first element of the collection or iterator satisfying a predicate, if any.
Finds the first element of the collection or iterator 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.
the predicate used to test elements.
an option value containing the first element in the collection or iterator
that satisfies p, or None if none exists.
Folds the elements of this collection or iterator using the specified associative binary operator.
Folds the elements of this collection or iterator using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
Note: will not terminate for infinite-sized collections.
a type parameter for the binary operator, a supertype of A.
a neutral element for the fold operation; may be added to the result
an arbitrary number of times, and must not change the result (e.g., Nil for list concatenation,
0 for addition, or 1 for multiplication).
a binary operator that must be associative.
the result of applying the fold operator op between all the elements and z, or z if this collection or iterator is empty.
Applies a binary operator to a start value and all elements of this collection or iterator, going left to right.
Applies a binary operator to a start value and all elements of this collection or iterator, going left to right.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
the result type of the binary operator.
the start value.
the binary operator.
the result of inserting op between consecutive elements of this collection or iterator,
going left to right with the start value z on the left:
op(...op(z, x_1), x_2, ..., x_n)
where x1, ..., xn are the elements of this collection or iterator.
Returns z if this collection or iterator is empty.
Applies a binary operator to all elements of this collection or iterator and a start value, going right to left.
Applies a binary operator to all elements of this collection or iterator and a start value, going right to left.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
the result type of the binary operator.
the start value.
the binary operator.
the result of inserting op between consecutive elements of this collection or iterator,
going right to left with the start value z on the right:
op(x_1, op(x_2, ... op(x_n, z)...))
where x1, ..., xn are the elements of this collection or iterator.
Returns z if this collection or iterator is empty.
Tests whether a predicate holds for all elements of this collection or iterator.
Tests whether a predicate holds for all elements of this collection or iterator.
Note: may not terminate for infinite-sized collections.
the predicate used to test elements.
true if this collection or iterator is empty or the given predicate p
holds for all elements of this collection or iterator, otherwise false.
Tests whether this collection or iterator is known to have a finite size.
Tests whether this collection or iterator 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.
true if this collection is known to have finite size,
false otherwise.
Tests whether the collection or iterator is empty.
Tests whether the collection or iterator is empty.
Note: Implementations in subclasses that are not repeatedly traversable must take
care not to consume any elements when isEmpty is called.
true if the collection or iterator contains no elements, false otherwise.
Tests whether this collection or iterator can be repeatedly traversed.
Tests whether this collection or iterator can be repeatedly traversed. Always true for Traversables and false for Iterators unless overridden.
true if it is repeatedly traversable, false otherwise.
Displays all elements of this collection or iterator in a string.
Displays all elements of this collection or iterator in a string.
a string representation of this collection or iterator. In the resulting string
the string representations (w.r.t. the method toString)
of all elements of this collection or iterator follow each other without any
separator string.
Displays all elements of this collection or iterator in a string using a separator string.
Displays all elements of this collection or iterator in a string using a separator string.
the separator string.
a string representation of this collection or iterator. In the resulting string
the string representations (w.r.t. the method toString)
of all elements of this collection or iterator are separated by the string sep.
List(1, 2, 3).mkString("|") = "1|2|3"
Displays all elements of this collection or iterator in a string using start, end, and separator strings.
Displays all elements of this collection or iterator in a string using start, end, and separator strings.
the starting string.
the separator string.
the ending string.
a string representation of this collection or iterator. The resulting string
begins with the string start and ends with the string
end. Inside, the string representations (w.r.t. the method
toString) of all elements of this collection or iterator are separated by
the string sep.
List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"
Tests whether the collection or iterator is not empty.
Tests whether the collection or iterator is not empty.
true if the collection or iterator contains at least one element, false otherwise.
Reduces the elements of this collection or iterator using the specified associative binary operator.
Reduces the elements of this collection or iterator using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
A type parameter for the binary operator, a supertype of A.
A binary operator that must be associative.
The result of applying reduce operator op between all the elements if the collection or iterator is nonempty.
UnsupportedOperationException
if this collection or iterator is empty.
Optionally applies a binary operator to all elements of this collection or iterator, going left to right.
Optionally applies a binary operator to all elements of this collection or iterator, going left to right.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
the result type of the binary operator.
the binary operator.
an option value containing the result of reduceLeft(op) if this collection or iterator is nonempty,
None otherwise.
Reduces the elements of this collection or iterator, if any, using the specified associative binary operator.
Reduces the elements of this collection or iterator, if any, using the specified associative binary operator.
The order in which operations are performed on elements is unspecified and may be nondeterministic.
A type parameter for the binary operator, a supertype of A.
A binary operator that must be associative.
An option value containing result of applying reduce operator op between all
the elements if the collection is nonempty, and None otherwise.
Applies a binary operator to all elements of this collection or iterator, going right to left.
Applies a binary operator to all elements of this collection or iterator, going right to left.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
the result type of the binary operator.
the binary operator.
the result of inserting op between consecutive elements of this collection or iterator,
going right to left:
op(x_1, op(x_2, ..., op(x_{n-1}, x_n)...)) where x1, ..., xn are the elements of this collection or iterator.
UnsupportedOperationException if this collection or iterator is empty.
Optionally applies a binary operator to all elements of this collection or iterator, going right to left.
Optionally applies a binary operator to all elements of this collection or iterator, going right to left.
Note: will not terminate for infinite-sized collections.
Note: might return different results for different runs, unless the underlying collection type is ordered or the operator is associative and commutative.
the result type of the binary operator.
the binary operator.
an option value containing the result of reduceRight(op) if this collection or iterator is nonempty,
None otherwise.
The size of this collection or iterator.
The size of this collection or iterator.
Note: will not terminate for infinite-sized collections.
the number of elements in this collection or iterator.
Uses the contents of this collection or iterator to create a new mutable buffer.
Uses the contents of this collection or iterator to create a new mutable buffer.
Note: will not terminate for infinite-sized collections.
a buffer containing all elements of this collection or iterator.
Converts this collection or iterator to an indexed sequence.
Converts this collection or iterator to an indexed sequence.
Note: will not terminate for infinite-sized collections.
an indexed sequence containing all elements of this collection or iterator.
Converts this collection or iterator to an iterable collection.
Converts this collection or iterator to an iterable collection. Note that
the choice of target Iterable is lazy in this default implementation
as this TraversableOnce may be lazy and unevaluated (i.e. it may
be an iterator which is only traversable once).
Note: will not terminate for infinite-sized collections.
an Iterable containing all elements of this collection or iterator.
Returns an Iterator over the elements in this collection or iterator.
Returns an Iterator over the elements in this collection or iterator. Will return the same Iterator if this instance is already an Iterator.
Note: will not terminate for infinite-sized collections.
an Iterator containing all elements of this collection or iterator.
Converts this collection or iterator to a list.
Converts this collection or iterator to a list.
Note: will not terminate for infinite-sized collections.
a list containing all elements of this collection or iterator.
Converts this collection or iterator to a sequence.
Converts this collection or iterator to a sequence. As with toIterable, it's lazy
in this default implementation, as this TraversableOnce may be
lazy and unevaluated.
Note: will not terminate for infinite-sized collections.
a sequence containing all elements of this collection or iterator.
Converts this collection or iterator to a set.
Converts this collection or iterator to a set.
Note: will not terminate for infinite-sized collections.
a set containing all elements of this collection or iterator.
Converts this collection or iterator to a stream.
Converts this collection or iterator to a stream.
a stream containing all elements of this collection or iterator.
Converts this collection or iterator to an unspecified Traversable.
Converts this collection or iterator to an unspecified Traversable. Will return the same collection if this instance is already Traversable.
Note: will not terminate for infinite-sized collections.
a Traversable containing all elements of this collection or iterator.
Converts this collection or iterator to a Vector.
Converts this collection or iterator to a Vector.
Note: will not terminate for infinite-sized collections.
a vector containing all elements of this collection or iterator.
[use case] Copies the elements of this collection or iterator to an array.
Copies the elements of this collection or iterator to an array.
Fills the given array xs with at most len elements of
this collection or iterator, starting at position start.
Copying will stop once either the end of the current collection or iterator is reached,
or the end of the target array is reached, or len elements have been copied.
Note: will not terminate for infinite-sized collections.
the array to fill.
the starting index.
the maximal number of elements to copy.
[use case] Copies the elements of this collection or iterator to an array.
Copies the elements of this collection or iterator to an array.
Fills the given array xs with values of this collection or iterator, beginning at index start.
Copying will stop once either the end of the current collection or iterator is reached,
or the end of the target array is reached.
Note: will not terminate for infinite-sized collections.
the array to fill.
the starting index.
[use case] Copies the elements of this collection or iterator to an array.
Copies the elements of this collection or iterator to an array.
Fills the given array xs with values of this collection or iterator.
Copying will stop once either the end of the current collection or iterator is reached,
or the end of the target array is reached.
Note: will not terminate for infinite-sized collections.
the array to fill.
[use case] Applies a function f to all elements of this collection or iterator.
Applies a function f to all elements of this collection or iterator.
Note: this method underlies the implementation of most other bulk operations. It's important to implement this method in an efficient way.
the function that is applied for its side-effect to every element.
The result of function f is discarded.
[use case] Finds the largest element.
Finds the largest element.
the largest element of this collection or iterator.
[use case] 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.
The result type of the function f.
The measuring function.
the first element of this collection or iterator with the largest value measured by function f.
[use case] Finds the smallest element.
Finds the smallest element.
the smallest element of this collection or iterator
[use case] 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.
The result type of the function f.
The measuring function.
the first element of this collection or iterator with the smallest value measured by function f.
[use case] Multiplies up the elements of this collection.
Multiplies up the elements of this collection.
the product of all elements in this collection or iterator of numbers of type Int.
Instead of Int, any other type T with an implicit Numeric[T] implementation
can be used as element type of the collection or iterator and as result type of product.
Examples of such types are: Long, Float, Double, BigInt.
[use case] Sums up the elements of this collection.
Sums up the elements of this collection.
the sum of all elements in this collection or iterator of numbers of type Int.
Instead of Int, any other type T with an implicit Numeric[T] implementation
can be used as element type of the collection or iterator and as result type of sum.
Examples of such types are: Long, Float, Double, BigInt.
[use case] Converts this collection or iterator into another by copying all elements.
Converts this collection or iterator into another by copying all elements.
Note: will not terminate for infinite-sized collections.
The collection type to build.
a new collection containing all elements of this collection or iterator.
[use case] Converts this collection or iterator to an array.
Converts this collection or iterator to an array.
Note: will not terminate for infinite-sized collections.
an array containing all elements of this collection or iterator.
An ClassTag must be available for the element type of this collection or iterator.
[use case] Converts this collection or iterator to a map.
Converts this collection or iterator to a map. This method is unavailable unless the elements are members of Tuple2, each ((T, U)) becoming a key-value pair in the map. Duplicate keys will be overwritten by later keys: if this is an unordered collection, which key is in the resulting map is undefined.
Note: will not terminate for infinite-sized collections.
a map of type immutable.Map[T, U]
containing all key/value pairs of type (T, U) of this collection or iterator.
A template trait for all traversable-once objects which may be traversed in parallel.
Methods in this trait are either abstract or can be implemented in terms of other methods.