We need a whole WithFilter class to honor the "doesn't create a new collection" contract even though it seems unlikely to matter much in a collection with max size 1.
Test two objects for inequality.
true if !(this == that), false otherwise.
Equivalent to x.hashCode except for boxed numeric types and null. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For null returns a hashcode where null.hashCode throws a NullPointerException.
a hash value consistent with ==
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.
the element type of the returned collection.
the class of the returned collection. Where possible, That is the same class as the current collection class Repr, but this depends on the element type B being admissible for that class, which means that an implicit instance of type CanBuildFrom[Repr, B, That] is found.
the traversable to append.
an implicit value of class CanBuildFrom which determines the result class That from the current representation type Repr and the new element type B.
a new collection of type That which contains all elements of this iterable collection followed by all elements of that.
As with ++, returns a new collection containing the elements from the left operand followed by the elements from the right operand.
It differs from ++ in that the right operand determines the type of the resulting collection rather than the left one. Mnemonic: the COLon is on the side of the new COLlection type.
Example:
scala> val x = List(1) x: List[Int] = List(1) scala> val y = LinkedList(2) y: scala.collection.mutable.LinkedList[Int] = LinkedList(2) scala> val z = x ++: y z: scala.collection.mutable.LinkedList[Int] = LinkedList(1, 2)
This overload exists because: for the implementation of ++: we should reuse that of ++ because many collections override it with more efficient versions.
Since TraversableOnce has no ++ method, we have to implement that directly, but Traversable and down can use the overload.
the element type of the returned collection.
the class of the returned collection. Where possible, That is the same class as the current collection class Repr, but this depends on the element type B being admissible for that class, which means that an implicit instance of type CanBuildFrom[Repr, B, That] is found.
the traversable to append.
an implicit value of class CanBuildFrom which determines the result class That from the current representation type Repr and the new element type B.
a new collection of type That which contains all elements of this iterable collection followed by all elements of that.
As with ++, returns a new collection containing the elements from the left operand followed by the elements from the right operand.
It differs from ++ in that the right operand determines the type of the resulting collection rather than the left one. Mnemonic: the COLon is on the side of the new COLlection type.
Example:
scala> val x = List(1) x: List[Int] = List(1) scala> val y = LinkedList(2) y: scala.collection.mutable.LinkedList[Int] = LinkedList(2) scala> val z = x ++: y z: scala.collection.mutable.LinkedList[Int] = LinkedList(1, 2)
the element type of the returned collection.
the traversable to append.
a new option which contains all elements of this option followed by all elements of that.
Applies a binary operator to a start value and all elements of this iterable collection, 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 iterable collection, 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 iterable collection.
Applies a binary operator to all elements of this iterable collection 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 iterable collection, 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 iterable collection.
The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).
true if the receiver object is equivalent to the argument; false otherwise.
Appends all elements of this iterable collection to a string builder. The written text consists of the string representations (w.r.t. the method toString) of all elements of this iterable 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
the string builder to which elements are appended.
the string builder b to which elements were appended.
Appends all elements of this iterable 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 iterable 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
the string builder to which elements are appended.
the separator string.
the string builder b to which elements were appended.
Appends all elements of this iterable 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 iterable 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)
the string builder to which elements are appended.
the starting string.
the separator string.
the ending string.
the string builder b to which elements were appended.
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 iterable collection 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
Cast the receiver object to be of type T0.
Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression 1.asInstanceOf[String] will throw a ClassCastException at runtime, while the expression List(1).asInstanceOf[List[String]] will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.
the receiver object.
ClassCastException if the receiver object is not an instance of the erasure of type T0.
Method called from equality methods, so that user-defined subclasses can refuse to be equal to other collections of the same kind.
The object with which this iterable collection should be compared
true, if this iterable collection can possibly equal that, false otherwise. The test takes into consideration only the run-time types of objects but ignores their elements.
Create a copy of the receiver object.
The default implementation of the clone method is platform dependent.
a copy of the receiver object.
Returns a scala.Some containing the result of applying pf to this scala.Option's contained value, if this option is nonempty and pf is defined for that value. Returns None otherwise.
the partial function.
the result of applying pf to this scala.Option's value (if possible), or None.
// Returns Some(HTTP) because the partial function covers the case.
Some("http") collect {case "http" => "HTTP"}
// Returns None because the partial function doesn't cover the case.
Some("ftp") collect {case "http" => "HTTP"}
// Returns None because the option is empty. There is no value to pass to the partial function.
None collect {case value => value}
Finds the first element of the iterable 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.
the partial function
an option value containing pf applied to the first value for which it is defined, or None if none exists.
Seq("a", 1, 5L).collectFirst({ case x: Int => x*10 }) = Some(10)
The factory companion object that builds instances of class Iterable. (or its Iterable superclass where class Iterable is not a Seq.)
Tests whether the option contains a given value as an element.
This is equivalent to:
option match {
case Some(x) => x == elem
case None => false
}
the element to test.
true if the option has an element that is equal (as determined by ==) to elem, false otherwise.
// Returns true because Some instance contains string "something" which equals "something".
Some("something") contains "something"
// Returns false because "something" != "anything".
Some("something") contains "anything"
// Returns false when method called on None.
None contains "anything"
Copies the elements of this option to an array. Fills the given array xs with at most len elements of this option, starting at position start. Copying will stop once either the end of the current option is reached, or the end of the target array is reached, or len elements have been copied.
the array to fill.
the starting index.
the maximal number of elements to copy.
Copies the elements of this option to an array. Fills the given array xs with values of this option. Copying will stop once either the end of the current option is reached, or the end of the target array is reached.
the array to fill.
Copies the elements of this option to an array. Fills the given array xs with values of this option, beginning at index start. Copying will stop once either the end of the current option is reached, or the end of the target array is reached.
the array to fill.
the starting index.
Copies all elements of this iterable collection to a buffer.
Note: will not terminate for infinite-sized collections.
The buffer to which elements are copied.
Counts the number of elements in the iterable collection which satisfy a predicate.
the predicate used to test elements.
the number of elements satisfying the predicate p.
Selects all elements except first n ones.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the number of elements to drop from this iterable collection.
a iterable collection consisting of all elements of this iterable collection except the first n ones, or else the empty iterable collection, if this iterable collection has less than n elements. If n is negative, don't drop any elements.
Selects all elements except last n ones.
Note: might return different results for different runs, unless the underlying collection type is ordered.
The number of elements to take
a iterable collection consisting of all elements of this iterable collection except the last n ones, or else the empty iterable collection, if this iterable collection has less than n elements.
Drops longest prefix of elements that satisfy a predicate.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the longest suffix of this iterable collection whose first element does not satisfy the predicate p.
Tests whether the argument (that) is a reference to the receiver object (this).
The eq method implements an equivalence relation on non-null instances of AnyRef, and has three additional properties:
x and y of type AnyRef, multiple invocations of x.eq(y) consistently returns true or consistently returns false.For any non-null instance x of type AnyRef, x.eq(null) and null.eq(x) returns false.
null.eq(null) returns true. When overriding the equals or hashCode methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (o1 eq o2), they should be equal to each other (o1 == o2) and they should hash to the same value (o1.hashCode == o2.hashCode).
true if the argument is a reference to the receiver object; false otherwise.
Returns true if this option is nonempty and the predicate p returns true when applied to this scala.Option's value. Otherwise, returns false.
This is equivalent to:
option match {
case Some(x) => p(x)
case None => false
}
the predicate to test
Returns this scala.Option if it is nonempty and applying the predicate p to this scala.Option's value returns true. Otherwise, return None.
This is equivalent to:
option match {
case Some(x) if p(x) => Some(x)
case _ => None
}
the predicate used for testing.
Returns this scala.Option if it is nonempty and applying the predicate p to this scala.Option's value returns false. Otherwise, return None.
This is equivalent to:
option match {
case Some(x) if !p(x) => Some(x)
case _ => None
}
the predicate used for testing.
Called by the garbage collector on the receiver object when there are no more references to the object.
The details of when and if the finalize method is invoked, as well as the interaction between finalize and non-local returns and exceptions, are all platform dependent.
not specified by SLS as a member of AnyRef
Finds the first element of the iterable 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.
the predicate used to test elements.
an option value containing the first element in the iterable collection that satisfies p, or None if none exists.
Returns the result of applying f to this scala.Option's value if this scala.Option is nonempty. Returns None if this scala.Option is empty. Slightly different from map in that f is expected to return an scala.Option (which could be None).
This is equivalent to:
option match {
case Some(x) => f(x)
case None => None
}
the function to apply
Returns the result of applying f to this scala.Option's value if the scala.Option is nonempty. Otherwise, evaluates expression ifEmpty.
This is equivalent to:
option match {
case Some(x) => f(x)
case None => ifEmpty
}
This is also equivalent to:
option map f getOrElse ifEmpty
the expression to evaluate if empty.
the function to apply if nonempty.
Applies a binary operator to a start value and all elements of this iterable collection, 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 iterable collection, 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 iterable collection. Returns z if this iterable collection is empty.
Applies a binary operator to all elements of this iterable collection 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 iterable collection, 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 iterable collection. Returns z if this iterable collection is empty.
Returns true if this option is empty or the predicate p returns true when applied to this scala.Option's value.
This is equivalent to:
option match {
case Some(x) => p(x)
case None => true
}
the predicate to test
Apply the given procedure f to the option's value, if it is nonempty. Otherwise, do nothing.
This is equivalent to:
option match {
case Some(x) => f(x)
case None => ()
}
the procedure to apply.
Returns string formatted according to given format string. Format strings are as for String.format (@see java.lang.String.format).
The generic builder that builds instances of Iterable at arbitrary element types.
Returns the option's value.
This is equivalent to:
option match {
case Some(x) => x
case None => throw new Exception
}
Returns the runtime class representation of the object.
a class object corresponding to the runtime type of the receiver.
Returns the option's value if the option is nonempty, otherwise return the result of evaluating default.
This is equivalent to:
option match {
case Some(x) => x
case None => default
}
the default expression.
Partitions this iterable collection into a map of iterable collections according to some discriminator function.
Note: this method is not re-implemented by views. This means when applied to a view it will always force the view and return a new iterable collection.
the type of keys returned by the discriminator function.
the discriminator function.
A map from keys to iterable collections such that the following invariant holds:
(xs groupBy f)(k) = xs filter (x => f(x) == k)
That is, every key k is bound to a iterable collection of those elements x for which f(x) equals k.
Partitions elements in fixed size iterable collections.
the number of elements per group
An iterator producing iterable collections of size size, except the last will be less than size size if the elements don't divide evenly.
scala.collection.Iterator, method grouped
Tests whether this iterable 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.
true if this collection is known to have finite size, false otherwise.
Selects the first element of this iterable collection.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the first element of this iterable collection.
NoSuchElementException if the iterable collection is empty.
Optionally selects the first element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the first element of this iterable collection if it is nonempty, None if it is empty.
Selects all elements except the last.
Note: might return different results for different runs, unless the underlying collection type is ordered.
a iterable collection consisting of all elements of this iterable collection except the last one.
UnsupportedOperationException if the iterable collection is empty.
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.
an iterator over all the inits of this iterable collection
List(1,2,3).inits = Iterator(List(1,2,3), List(1,2), List(1), Nil)
Returns true if the option is an instance of scala.Some, false otherwise.
This is equivalent to:
option match {
case Some(_) => true
case None => false
}
Returns true if the option is None, false otherwise.
This is equivalent to:
option match {
case Some(_) => false
case None => true
}
Test whether the dynamic type of the receiver object is T0.
Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression 1.isInstanceOf[String] will return false, while the expression List(1).isInstanceOf[List[String]] will return true. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.
true if the receiver object is an instance of erasure of type T0; false otherwise.
Tests whether this iterable collection can be repeatedly traversed.
true
Returns a singleton iterator returning the scala.Option's value if it is nonempty, or an empty iterator if the option is empty.
Selects the last element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
The last element of this iterable collection.
NoSuchElementException If the iterable collection is empty.
Optionally selects the last element.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the last element of this iterable collection$ if it is nonempty, None if it is empty.
Returns a scala.Some containing the result of applying f to this scala.Option's value if this scala.Option is nonempty. Otherwise return None.
This is equivalent to:
option match {
case Some(x) => Some(f(x))
case None => None
}
the function to apply
This is similar to flatMap except here, f does not need to wrap its result in an scala.Option.
flatMap
foreach
Finds the largest element.
the largest element of this option.
UnsupportedOperationException if this option is empty.
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 option with the largest value measured by function f.
UnsupportedOperationException if this option is empty.
Finds the smallest element.
the smallest element of this option
UnsupportedOperationException if this option is empty.
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 option with the smallest value measured by function f.
UnsupportedOperationException if this option is empty.
Displays all elements of this iterable collection in a string.
a string representation of this iterable collection. In the resulting string the string representations (w.r.t. the method toString) of all elements of this iterable collection follow each other without any separator string.
Displays all elements of this iterable collection in a string using a separator string.
the separator string.
a string representation of this iterable collection. In the resulting string the string representations (w.r.t. the method toString) of all elements of this iterable collection are separated by the string sep.
List(1, 2, 3).mkString("|") = "1|2|3"
Displays all elements of this iterable collection in a string using start, end, and separator strings.
the starting string.
the separator string.
the ending string.
a string representation of this iterable collection. The resulting string begins with the string start and ends with the string end. Inside, the string representations (w.r.t. the method toString) of all elements of this iterable collection are separated by the string sep.
List(1, 2, 3).mkString("(", "; ", ")") = "(1; 2; 3)"
Equivalent to !(this eq that).
true if the argument is not a reference to the receiver object; false otherwise.
Returns false if the option is None, true otherwise.
This is equivalent to:
option match {
case Some(_) => true
case None => false
}
Implemented here to avoid the implicit conversion to Iterable.
Wakes up a single thread that is waiting on the receiver object's monitor.
not specified by SLS as a member of AnyRef
Wakes up all threads that are waiting on the receiver object's monitor.
not specified by SLS as a member of AnyRef
Returns this scala.Option if it is nonempty, otherwise return the result of evaluating alternative.
This is equivalent to:
option match {
case Some(x) => Some(x)
case None => alternative
}
the alternative expression.
Returns the option's value if it is nonempty, or null if it is empty.
Although the use of null is discouraged, code written to use scala.Option must often interface with code that expects and returns nulls.
This is equivalent to:
option match {
case Some(x) => x
case None => null
}
Returns a parallel implementation of this collection.
For most collection types, this method creates a new parallel collection by copying all the elements. For these collection, par takes linear time. Mutable collections in this category do not produce a mutable parallel collection that has the same underlying dataset, so changes in one collection will not be reflected in the other one.
Specific collections (e.g. ParArray or mutable.ParHashMap) override this default behaviour by creating a parallel collection which shares the same underlying dataset. For these collections, par takes constant or sublinear time.
All parallel collections return a reference to themselves.
a parallel implementation of this collection
Partitions this iterable collection in two iterable collections according to a predicate.
the predicate on which to partition.
a pair of iterable collections: the first iterable collection consists of all elements that satisfy the predicate p and the second iterable collection consists of all elements that don't. The relative order of the elements in the resulting iterable collections is the same as in the original iterable collection.
Multiplies up the elements of this collection.
the product of all elements in this option 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 option and as result type of product. Examples of such types are: Long, Float, Double, BigInt.
Reduces the elements of this iterable collection 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 iterable collection is nonempty.
UnsupportedOperationException if this iterable collection is empty.
Applies a binary operator to all elements of this iterable collection, 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.
the result of inserting op between consecutive elements of this iterable collection, going left to right:
op( op( ... op(x_1, x_2) ..., x_{n-1}), x_n)
where x1, ..., xn are the elements of this iterable collection.
UnsupportedOperationException if this iterable collection is empty.
Optionally applies a binary operator to all elements of this iterable collection, 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 iterable collection is nonempty, None otherwise.
Reduces the elements of this iterable collection, 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 iterable collection, 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 iterable collection, going right to left:
op(x_1, op(x_2, ..., op(x_{n-1}, x_n)...))
where x1, ..., xn are the elements of this iterable collection.
UnsupportedOperationException if this iterable collection is empty.
Optionally applies a binary operator to all elements of this iterable collection, 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 iterable collection is nonempty, None otherwise.
The collection of type iterable collection underlying this TraversableLike object. By default this is implemented as the TraversableLike object itself, but this can be overridden.
Checks if the other iterable collection contains the same elements in the same order as this option.
the collection to compare with.
true, if both collections contain the same elements in the same order, false otherwise.
Computes a prefix scan of the elements of the collection.
Note: The neutral element z may be applied more than once.
element type of the resulting collection
type of the resulting collection
neutral element for the operator op
the associative operator for the scan
combiner factory which provides a combiner
a new iterable collection containing the prefix scan of the elements in this iterable collection
Produces a collection containing cumulative results of applying the operator 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.
the type of the elements in the resulting collection
the actual type of the resulting collection
the initial value
the binary operator applied to the intermediate result and the element
an implicit value of class CanBuildFrom which determines the result class That from the current representation type Repr and the new element type B.
collection with intermediate results
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.
Example:
List(1, 2, 3, 4).scanRight(0)(_ + _) == List(10, 9, 7, 4, 0)
the type of the elements in the resulting collection
the actual type of the resulting collection
the initial value
the binary operator applied to the intermediate result and the element
an implicit value of class CanBuildFrom which determines the result class That from the current representation type Repr and the new element type B.
collection with intermediate results
(Changed in version 2.9.0) The behavior of scanRight has changed. The previous behavior can be reproduced with scanRight.reverse.
A version of this collection with all of the operations implemented sequentially (i.e., in a single-threaded manner).
This method returns a reference to this collection. In parallel collections, it is redefined to return a sequential implementation of this collection. In both cases, it has O(1) complexity.
a sequential view of the collection.
The size of this iterable collection.
Note: will not terminate for infinite-sized collections.
the number of elements in this iterable collection.
Selects an interval of elements. The returned collection is made up of all elements x which satisfy the invariant:
from <= indexOf(x) < until
Note: might return different results for different runs, unless the underlying collection type is ordered.
a iterable collection containing the elements greater than or equal to index from extending up to (but not including) index until of this iterable collection.
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.)
the number of elements per group
the distance between the first elements of successive groups
An iterator producing iterable collections of size size, except the last element (which may be the only element) will be truncated if there are fewer than size elements remaining to be grouped.
scala.collection.Iterator, method sliding
Groups elements in fixed size blocks by passing a "sliding window" over them (as opposed to partitioning them, as is done in grouped.) The "sliding window" step is set to one.
the number of elements per group
An iterator producing iterable collections of size size, except the last element (which may be the only element) will be truncated if there are fewer than size elements remaining to be grouped.
scala.collection.Iterator, method sliding
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.
a pair consisting of the longest prefix of this iterable collection whose elements all satisfy p, and the rest of this iterable collection.
Splits this iterable collection into two at a given position. Note: c splitAt n is equivalent to (but possibly more efficient than) (c take n, c drop n).
Note: might return different results for different runs, unless the underlying collection type is ordered.
the position at which to split.
a pair of iterable collections consisting of the first n elements of this iterable collection, and the other elements.
Defines the prefix of this object's toString representation.
a string representation which starts the result of toString applied to this iterable collection. By default the string prefix is the simple name of the collection class iterable collection.
Sums up the elements of this collection.
the sum of all elements in this option 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 option and as result type of sum. Examples of such types are: Long, Float, Double, BigInt.
Selects all elements except the first.
Note: might return different results for different runs, unless the underlying collection type is ordered.
a iterable collection consisting of all elements of this iterable collection except the first one.
java.lang.UnsupportedOperationException if the iterable collection is empty.
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.
an iterator over all the tails of this iterable collection
List(1,2,3).tails = Iterator(List(1,2,3), List(2,3), List(3), Nil)
Selects first n elements.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the number of elements to take from this iterable collection.
a iterable collection consisting only of the first n elements of this iterable collection, or else the whole iterable collection, if it has less than n elements. If n is negative, returns an empty iterable collection.
Selects last n elements.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the number of elements to take
a iterable collection consisting only of the last n elements of this iterable collection, or else the whole iterable collection, if it has less than n elements.
Takes longest prefix of elements that satisfy a predicate.
Note: might return different results for different runs, unless the underlying collection type is ordered.
the longest prefix of this iterable collection whose elements all satisfy the predicate p.
Converts this option into another by copying all elements.
The collection type to build.
a new collection containing all elements of this option.
Converts this option to an array.
an array containing all elements of this option. An ClassTag must be available for the element type of this option.
Uses the contents of this iterable collection to create a new mutable buffer.
Note: will not terminate for infinite-sized collections.
a buffer containing all elements of this iterable collection.
Converts this iterable collection to an indexed sequence.
Note: will not terminate for infinite-sized collections.
an indexed sequence containing all elements of this iterable collection.
Returns this iterable collection as an iterable collection.
A new collection will not be built; lazy collections will stay lazy.
Note: will not terminate for infinite-sized collections.
an Iterable containing all elements of this iterable collection.
Returns an Iterator over the elements in this iterable collection. Produces the same result as iterator.
Note: will not terminate for infinite-sized collections.
an Iterator containing all elements of this iterable collection.
Returns a scala.util.Right containing the given argument right if this is empty, or a scala.util.Left containing this scala.Option's value if this scala.Option is nonempty.
This is equivalent to:
option match {
case Some(x) => Left(x)
case None => Right(right)
}
the expression to evaluate and return if this is empty
Returns a singleton list containing the scala.Option's value if it is nonempty, or the empty list if the scala.Option is empty.
This is equivalent to:
option match {
case Some(x) => List(x)
case None => Nil
}
Converts this option 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.
a map of type immutable.Map[T, U] containing all key/value pairs of type (T, U) of this option.
Returns a scala.util.Left containing the given argument left if this scala.Option is empty, or a scala.util.Right containing this scala.Option's value if this is nonempty.
This is equivalent to:
option match {
case Some(x) => Right(x)
case None => Left(left)
}
the expression to evaluate and return if this is empty
Converts this iterable collection 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 iterable collection.
Converts this iterable collection to a set.
Note: will not terminate for infinite-sized collections.
a set containing all elements of this iterable collection.
Converts this iterable collection to a stream.
a stream containing all elements of this iterable collection.
Converts this iterable collection to a string.
a string representation of this collection. By default this string consists of the stringPrefix of this iterable collection, followed by all elements separated by commas and enclosed in parentheses.
Converts this iterable collection 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 iterable collection.
Converts this iterable collection to a Vector.
Note: will not terminate for infinite-sized collections.
a vector containing all elements of this iterable collection.
Transposes this iterable collection of traversable 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))
the type of the elements of each traversable collection.
an implicit conversion which asserts that the element type of this iterable collection is a Traversable.
a two-dimensional iterable collection of iterable collections which has as nth row the nth column of this iterable collection.
(Changed in version 2.9.0) transpose throws an IllegalArgumentException if collections are not uniformly sized.
IllegalArgumentException if all collections in this iterable collection are not of the same size.
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))
the type of the first half of the element pairs
the type of the second half of the element pairs
an implicit conversion which asserts that the element type of this iterable collection is a pair.
a pair of iterable collections, containing the first, respectively second half of each element pair of this iterable collection.
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))
the type of the first member of the element triples
the type of the second member of the element triples
the type of the third member of the element triples
an implicit conversion which asserts that the element type of this iterable collection is a triple.
a triple of iterable collections, containing the first, second, respectively third member of each element triple of this iterable collection.
Creates a non-strict view of a slice of this iterable collection.
Note: the difference between view and slice is that view produces a view of the current iterable collection, whereas slice produces a new iterable collection.
Note: view(from, to) is equivalent to view.slice(from, to)
Note: might return different results for different runs, unless the underlying collection type is ordered.
the index of the first element of the view
the index of the element following the view
a non-strict view of a slice of this iterable collection, starting at index from and extending up to (but not including) index until.
Creates a non-strict view of this iterable collection.
a non-strict view of this iterable collection.
Necessary to keep scala.Option from being implicitly converted to scala.collection.Iterable in for comprehensions.
Returns a option formed from this option 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.
the type of the second half of the returned pairs
The iterable providing the second half of each result pair
a new option containing pairs consisting of corresponding elements of this option and that. The length of the returned collection is the minimum of the lengths of this option and that.
Returns a option formed from this option 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.
the type of the second half of the returned pairs
The iterable providing the second half of each result pair
the element to be used to fill up the result if this option is shorter than that.
the element to be used to fill up the result if that is shorter than this option.
a new option containing pairs consisting of corresponding elements of this option and that. The length of the returned collection is the maximum of the lengths of this option and that. If this option is shorter than that, thisElem values are used to pad the result. If that is shorter than this option, thatElem values are used to pad the result.
Zips this option with its indices.
A new option containing pairs consisting of all elements of this option paired with their index. Indices start at 0.
List("a", "b", "c").zipWithIndex = List(("a", 0), ("b", 1), ("c", 2))
Builds a new collection by applying a partial function to all elements of this option on which the function is defined.
the element type of the returned collection.
the partial function which filters and maps the option.
a new option resulting from applying the given partial function pf to each element on which it is defined and collecting the results. The order of the elements is preserved.
(some: Iterable[A]).collect(pf)
Tests whether a predicate holds for at least one element of this iterable collection.
Note: may not terminate for infinite-sized collections.
the predicate used to test elements.
false if this iterable collection is empty, otherwise true if the given predicate p holds for some of the elements of this iterable collection, otherwise false
(some: Iterable[A]).exists(p)
Selects all elements of this iterable collection which satisfy a predicate.
the predicate used to test elements.
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.
(some: Iterable[A]).filter(p)
Selects all elements of this iterable collection which do not satisfy a predicate.
the predicate used to test elements.
a new iterable collection consisting of all elements of this iterable collection that do not satisfy the given predicate p. The order of the elements is preserved.
(some: Iterable[A]).filterNot(p)
Builds a new collection by applying a function to all elements of this option 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 option. 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 => 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)
the element type of the returned collection.
the function to apply to each element.
a new option resulting from applying the given collection-valued function f to each element of this option and concatenating the results.
(some: Iterable[A]).flatMap(f)
Converts this option of traversable collections into a option formed by the elements of these traversable collections.
The resulting collection's type will be guided by the static type of option. 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)
the type of the elements of each traversable collection.
a new option resulting from concatenating all element options.
(some: Iterable[A]).flatten
Folds the elements of this iterable collection 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 iterable collection is empty.
(some: Iterable[A]).fold(z)(op)
Tests whether a predicate holds for all elements of this iterable collection.
Note: may not terminate for infinite-sized collections.
the predicate used to test elements.
true if this iterable collection is empty or the given predicate p holds for all elements of this iterable collection, otherwise false.
(some: Iterable[A]).forall(p)
Applies a function f to all elements of this option.
Note: this method underlies the implementation of most other bulk operations. Subclasses should re-implement this method if a more efficient implementation exists.
the function that is applied for its side-effect to every element. The result of function f is discarded.
(some: Iterable[A]).foreach(f)
Tests whether this iterable collection is empty.
true if the iterable collection contain no elements, false otherwise.
(some: Iterable[A]).isEmpty
Creates a new iterator over all elements contained in this iterable object.
the new iterator
(some: Iterable[A]).iterator
Builds a new collection by applying a function to all elements of this option.
the element type of the returned collection.
the function to apply to each element.
a new option resulting from applying the given function f to each element of this option and collecting the results.
(some: Iterable[A]).map(f)
Tests whether the iterable collection is not empty.
true if the iterable collection contains at least one element, false otherwise.
(some: Iterable[A]).nonEmpty
Converts this iterable collection to a list.
Note: will not terminate for infinite-sized collections.
a list containing all elements of this iterable collection.
(some: Iterable[A]).toList
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.
the predicate used to test elements.
an object of class WithFilter, which supports map, flatMap, foreach, and withFilter operations. All these operations apply to those elements of this iterable collection which satisfy the predicate p.
(some: Iterable[A]).withFilter(p)
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Licensed under the Apache License, Version 2.0.
https://www.scala-lang.org/api/2.12.9/scala/Some.html
Class
Some[A]represents existing values of typeA.1.0