Crate itertools

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itertools Extra iterator adaptors, iterator methods, functions, and macros.

Extra iterator adaptors, functions and macros.

To extend Iterator with methods in this crate, import the Itertools trait:

use itertools::Itertools;

Now, new methods like interleave are available on all iterators:

use itertools::Itertools;

let it = (1..3).interleave(vec![-1, -2]);
itertools::assert_equal(it, vec![1, -1, 2, -2]);

Most iterator methods are also provided as functions (with the benefit that they convert parameters using IntoIterator):

use itertools::interleave;

for elt in interleave(&[1, 2, 3], &[2, 3, 4]) {
    /* loop body */
}

§Crate Features

use_std
- Enabled by default.
- Disable to compile itertools using #![no_std]. This disables any item that depend on allocations (see the use_alloc feature) and hash maps (like unique, counts, into_grouping_map and more).
use_alloc
- Enabled by default.
- Enables any item that depend on allocations (like chunk_by, kmerge, join and many more).

§Rust Version

This version of itertools requires Rust 1.63.0 or later.

Modules§

__std_iter: Composable external iteration.
structs: The concrete iterator types.
traits: Traits helpful for using certain Itertools methods in generic contexts.

Macros§

chain: Chain zero or more iterators together into one sequence.
iproduct: Create an iterator over the “cartesian product” of iterators.
izip: Create an iterator running multiple iterators in lockstep.

Structs§

Batching: A “meta iterator adaptor”. Its closure receives a reference to the iterator and may pick off as many elements as it likes, to produce the next iterator element.
Chunk: An iterator for the elements in a single chunk.
ChunkBy: ChunkBy is the storage for the lazy grouping operation.
Chunks: An iterator that yields the Chunk iterators.
CircularTupleWindows: An iterator over all windows, wrapping back to the first elements when the window would otherwise exceed the length of the iterator, producing tuples of a specific size.
CombinationsWithReplacement: An iterator to iterate through all the n-length combinations in an iterator, with replacement.
ExactlyOneError: Iterator returned for the error case of Itertools::exactly_one() This iterator yields exactly the same elements as the input iterator.
FilterMapOk: An iterator adapter to filter and apply a transformation on values within a nested Result::Ok.
FilterOk: An iterator adapter to filter values within a nested Result::Ok.
FlattenOk: An iterator adaptor that flattens Result::Ok values and allows Result::Err values through unchanged.
Format: Format all iterator elements lazily, separated by sep.
FormatWith: Format all iterator elements lazily, separated by sep.
Group: An iterator for the elements in a single group.
GroupingMap: GroupingMap is an intermediate struct for efficient group-and-fold operations. It groups elements by their key and at the same time fold each group using some aggregating operation.
Groups: An iterator that yields the Group iterators.
Interleave: An iterator adaptor that alternates elements from two iterators until both run out.
InterleaveShortest: An iterator adaptor that alternates elements from the two iterators until one of them runs out.
IntersperseWith: An iterator adaptor to insert a particular value created by a function between each element of the adapted iterator.
IntoChunks: ChunkLazy is the storage for a lazy chunking operation.
Iterate: An iterator that infinitely applies function to value and yields results.
KMergeBy: An iterator adaptor that merges an abitrary number of base iterators according to an ordering function.
MergeBy: An iterator adaptor that merges the two base iterators in ascending order. If both base iterators are sorted (ascending), the result is sorted.
MultiPeek: See multipeek() for more information.
MultiProduct: An iterator adaptor that iterates over the cartesian product of multiple iterators of type I.
PadUsing: An iterator adaptor that pads a sequence to a minimum length by filling missing elements using a closure.
PeekNth: See peek_nth() for more information.
PeekingTakeWhile: An iterator adaptor that takes items while a closure returns true.
Permutations: An iterator adaptor that iterates through all the k-permutations of the elements from an iterator.
Positions: An iterator adapter to get the positions of each element that matches a predicate.
Powerset: An iterator to iterate through the powerset of the elements from an iterator.
ProcessResults: An iterator that produces only the T values as long as the inner iterator produces Ok(T).
Product: An iterator adaptor that iterates over the cartesian product of the element sets of two iterators I and J.
PutBack: An iterator adaptor that allows putting back a single item to the front of the iterator.
PutBackN: An iterator adaptor that allows putting multiple items in front of the iterator.
RcIter: A wrapper for Rc<RefCell<I>>, that implements the Iterator trait.
RepeatN: An iterator that produces n repetitions of an element.
TakeWhileInclusive: An iterator adaptor that consumes elements while the given predicate is true, including the element for which the predicate first returned false.
TakeWhileRef: An iterator adaptor that borrows from a Clone-able iterator to only pick off elements while the predicate returns true.
Tee: One half of an iterator pair where both return the same elements.
TupleBuffer: An iterator over a incomplete tuple.
TupleCombinations: An iterator to iterate through all combinations in a Clone-able iterator that produces tuples of a specific size.
TupleWindows: An iterator over all contiguous windows that produces tuples of a specific size.
Tuples: An iterator that groups the items in tuples of a specific size.
UnfoldDeprecated: See unfold for more information.
Unique: An iterator adapter to filter out duplicate elements.
UniqueBy: An iterator adapter to filter out duplicate elements.
Update: An iterator adapter to apply a mutating function to each element before yielding it.
WhileSome: An iterator adaptor that filters Option<A> iterator elements and produces A. Stops on the first None encountered.
WithPosition: An iterator adaptor that wraps each element in an Position.
Zip: See multizip for more information.
ZipEq: An iterator which iterates two other iterators simultaneously and panic if they have different lengths.
ZipLongest: An iterator which iterates two other iterators simultaneously and wraps the elements in EitherOrBoth.

Enums§

Diff: A type returned by the diff_with function.
Either: The enum Either with variants Left and Right is a general purpose sum type with two cases.
EitherOrBoth: Value that either holds a single A or B, or both.
FoldWhile: An enum used for controlling the execution of fold_while.
MinMaxResult: MinMaxResult is an enum returned by minmax.
Position: The first component of the value yielded by WithPosition. Indicates the position of this element in the iterator results.

Traits§

Itertools: An Iterator blanket implementation that provides extra adaptors and methods.
MultiUnzip: An iterator that can be unzipped into multiple collections.
PeekingNext: An iterator that allows peeking at an element before deciding to accept it.

Functions§

all: Test whether the predicate holds for all elements in the iterable.
any: Test whether the predicate holds for any elements in the iterable.
assert_equal: Assert that two iterables produce equal sequences, with the same semantics as equal(a, b).
chain: Takes two iterables and creates a new iterator over both in sequence.
cloned: Create an iterator that clones each element from &T to T.
concat: Combine all an iterator’s elements into one element by using Extend.
cons_tuples: Create an iterator that maps for example iterators of ((A, B), C) to (A, B, C).
diff_with: Compares every element yielded by both i and j with the given function in lock-step and returns a Diff which describes how j differs from i.
enumerate: Iterate iterable with a running index.
equal: Return true if both iterables produce equal sequences (elements pairwise equal and sequences of the same length), false otherwise.
fold: Perform a fold operation over the iterable.
interleave: Create an iterator that interleaves elements in i and j.
intersperse: Iterate iterable with a particular value inserted between each element.
intersperse_with: Iterate iterable with a particular value created by a function inserted between each element.
iterate: Creates a new iterator that infinitely applies function to value and yields results.
join: Combine all iterator elements into one String, separated by sep.
kmerge: Create an iterator that merges elements of the contained iterators using the ordering function.
kmerge_by: Create an iterator that merges elements of the contained iterators.
max: Return the maximum value of the iterable.
merge: Create an iterator that merges elements in i and j.
merge_join_by: Return an iterator adaptor that merge-joins items from the two base iterators in ascending order.
min: Return the minimum value of the iterable.
multipeek: An iterator adaptor that allows the user to peek at multiple .next() values without advancing the base iterator.
multiunzip: Converts an iterator of tuples into a tuple of containers.
multizip: An iterator that generalizes .zip() and allows running multiple iterators in lockstep.
partition: Partition a sequence using predicate pred so that elements that map to true are placed before elements which map to false.
peek_nth: A drop-in replacement for std::iter::Peekable which adds a peek_nth method allowing the user to peek at a value several iterations forward without advancing the base iterator.
process_results: “Lift” a function of the values of an iterator so that it can process an iterator of Result values instead.
put_back: Create an iterator where you can put back a single item
put_back_n: Create an iterator where you can put back multiple values to the front of the iteration.
rciter: Return an iterator inside a Rc<RefCell<_>> wrapper.
repeat_n: Create an iterator that produces n repetitions of element.
rev: Iterate iterable in reverse.
sorted: Sort all iterator elements into a new iterator in ascending order.
sorted_unstable: Sort all iterator elements into a new iterator in ascending order. This sort is unstable (i.e., may reorder equal elements).
unfoldDeprecated: Creates a new unfold source with the specified closure as the “iterator function” and an initial state to eventually pass to the closure
zipDeprecated: Converts the arguments to iterators and zips them.
zip_eq: Zips two iterators but panics if they are not of the same length.

Type Aliases§

ArrayCombinations: Iterator for const generic combinations returned by .array_combinations()
Coalesce: An iterator adaptor that may join together adjacent elements.
Combinations: Iterator for Vec valued combinations returned by .combinations()
ConsTuples: An iterator that maps an iterator of tuples like ((A, B), C) to an iterator of (A, B, C).
Dedup: An iterator adaptor that removes repeated duplicates.
DedupBy: An iterator adaptor that removes repeated duplicates, determining equality using a comparison function.
DedupByWithCount: An iterator adaptor that removes repeated duplicates, while keeping a count of how many repeated elements were present. This will determine equality using a comparison function.
DedupWithCount: An iterator adaptor that removes repeated duplicates, while keeping a count of how many repeated elements were present.
Duplicates: An iterator adapter to filter out duplicate elements.
DuplicatesBy: An iterator adapter to filter for duplicate elements.
GroupByDeprecated: See ChunkBy.
GroupingMapBy: GroupingMapBy is an intermediate struct for efficient group-and-fold operations.
Intersperse: An iterator adaptor to insert a particular value between each element of the adapted iterator.
KMerge: An iterator adaptor that merges an abitrary number of base iterators in ascending order. If all base iterators are sorted (ascending), the result is sorted.
MapInto: An iterator adapter to apply Into conversion to each element.
MapOk: An iterator adapter to apply a transformation within a nested Result::Ok.
Merge: An iterator adaptor that merges the two base iterators in ascending order. If both base iterators are sorted (ascending), the result is sorted.
MergeJoinBy: An iterator adaptor that merge-joins items from the two base iterators in ascending order.

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