This release restores pairwise, which was mistakenly removed in 11.0.0 instead of being deprecated. It is now marked as deprecated and will be removed in a future major release. Use itertools.pairwise as a replacement.

Potentially breaking changes

• Python 3.9 support was dropped, since it went EOL on 2025-10-31
• callback_iter is deprecated. It will be removed in a future major release.
• iequals no longer returns True when called with ([], [ANY]) (thanks to rhettinger and pochmann3)
• The pred argument for locate and replace must now be able to
  handle a variable number of arguments. See their docstrings for details. (thanks to veeceey, james-wasson, and pochmann3)
• unique_everseen now raises TypeError when input elements are not hashable.
  The silent fallback mechanism for unhashable inputs has been removed. (thanks to rhettinger and karlicoss)
• windowed now raises ValueError when given a window size of 0 (thanks to rhettinger and brevzin)
• Parameter names for flatten, iter_except, repeatfunc, prepend, transpose,
  and sum_of_squares have been changed. Code that uses these functions will need to be updated if it
  uses keywords for positional arguments. (thanks to rhettinger)

New functions

• concurrent_tee: similar to tee, but with guaranteed threading
  semantics (thanks to rhettinger)
• random_derangement: returns a random derangement of elements from an
  iterable (thanks to rhettinger)
• running_mean: yields the mean of values in an iterable, or in a sliding
  window (thanks to rhettinger)
• running_statistics: provides statistics for the values in an iterable, or
  in a sliding window (thanks to rhettinger)
• serialize: wraps a non-concurrent iterator with a lock to enforce
  sequential access (thanks to rhettinger)
• synchronized: wraps an iterator-returning callable to make its iterators
  thread-safe (thanks to rhettinger)
• sized_iterator: wraps an iterable with a known length and implements __len__ (thanks to assaf127)

Changes to existing functions

• The type hints for always_iterable were improved (thanks to rhettinger and maltevesper)
• A potential bug in callback_iter was fixed
• A bug in exactly_n's handling of negative arguments was fixed (thanks to rhettinger)
• extract`` now accepts a monotonic` argument for improved performance (thanks to rhettinger)
• A bug in numeric_range's handling of negative steps was fixed (thanks to bysiber)
• grouper implementation was updated to match the itertools docs (thanks to rhettinger)
• nth_product, product_index, gray_product,
  partial_product, nth_product, product_index, and
  random_product now accept a repeat keyword argument (thanks to rhettinger)
• powerset_of_sets can now construct frozenset instances (thanks to rhettinger)
• The type hints for stagger were improved (thanks to nathanjmcdougall)
• Memory efficiency was improved for partition was improved (thanks to rhettinger and yueyinqiu)
• Performance for the functions count_cycle, difference,
  random_product, was improved nth_combination, nth_combination_with_replacement,
  nth_permuwas improvedtation, nth_product, product_index,
  random_permutation, substrings, and value_chain was
  improved (thanks to rhettinger)
• Performance for ichunked was improved (thanks to pochmann3 and rhettinger)

Other changes

• The docstrings for several functions were improved (thanks to nathanjmcdougall, olliemath, r266-tech, and rhettinger)

What's Changed

• Fix typo in version history for 10.7.0 by bbayles in #981
• Issue 980: Fix variable names: iterable vs iterator by rhettinger in #982
• Improve docstrings for dft, idft, and multinomial by rhettinger in #983
• Add a note about polynomial endianness by bbayles in #984
• Add SPDX license identifier by cdce8p in #978
• Remove setup.py file by cdce8p in #979
• Include derangements by itself by bbayles in #985
• Add derangements by debruijn in #946
• Issue 986: argmin and argmax by bbayles in #988
• Split-out the integer math functions by rhettinger in #990
• Spelling, grammar, punctuation, and usage by rhettinger in #991
• Fix the return type of more_itertools.batched by qobilidop in #993
• Fix duplicate words in version_history.rst by saadmanrafat in #992
• Improve islice_extended memory usage when start<0 and step>0 by ben42code in #995
• Unittest islice_extended impact on iterated elements lifecycle by ben42code in #996
• convolve() is agnostic to endianness by rhettinger in #997
• Sample simplification by rhettinger in #998
• Issue 1005: Document difference from builtin min() and max(). by rhettinger in #1008
• General cleanups by rhettinger in #1007
• Fix broken link by rhettinger in #1004
• Add option for nth_prime() to be approximated by rhettinger in #1002
• before_and_after improvement by pochmann3 in #1012
• Fast paths instead of applying an identity function by rhettinger in #1018
• Speed-up _complex_sumprod() by rhettinger in #1000
• Improve islice_extended memory usage when stop<0 and step>0 by ben42code in #999
• Add derangements() to the doc indexes by rhettinger in #1020
• Improve readability/findability with combinatoric subsections by rhettinger in #1022
• Fix 1009: Confused docstring for minmax() by rhettinger in #1021
• Improve interleave_longest by pochmann3 in #1027
• Issue 1001: fix last() when reversed is None by inventshah in #1028
• Issue 1029: fix batched IDE/help() docs by inventshah in #1031
• Improve mark_ends by pochmann3 in #1035
• Add usage notes for sample() by rhettinger in #1037
• Fix docstring and comment in private _nth_prime_bounds function by rhettinger in #1036
• Fix linespacing by rhettinger in #1038
• Add running_median by rhettinger in #1039
• running_median() with windowed data by rhettinger in #1040
• Pin furo to 2024.08.06 by bbayles in #1043
• docs: Fix invisible REPL output in HTML dark mode by moreati in #1045
• Use python instead of python3 when running tests by ktbarrett in #1051
• Issue 1044: Add new tool: extract() by rhettinger in #1056
• Test 3.14.0-rc.2 by bbayles in #1060
• unzip: replace custom itemgetter by pochmann3 in #1059
• Add interleave_randomly by ktbarrett in #1048
• Issue 1003: Multidimensional reshape() by rhettinger in #1062
• Get coverage to 100% by rhettinger in #1065
• Improve count_cycle() by rhettinger in #1066
• Clarify how derangements treats duplicate inputs by rhettinger in #1069
• Readability improvement for reshaped() by rhettinger in #1067
• Clean-up tail(). Prefer try/except over the Sized ABC. by rhettinger in #1068
• Version 10.8.0 by bbayles in #1071

Full Changelog: v10.7.0...v10.8.0

See the change log here for details.

• New functions:

  • is_prime and nth_prime were added (thanks to JamesParrott and rhettinger)
  • loops was added (thanks to rhettinger)

• Changes to existing functions:

  • factor was optimized to handle larger inputs and use less memory (thanks to rhettinger)
  • spy was optimized to enable nested calls (thanks to rhettinger)
  • polynomial_from_roots was made non-recursive and able to handle larger numbers of roots (thanks to pochmann3 and rhettinger)
  • is_sorted now only relies on less than comparisons (thanks to rhettinger)
  • The docstring for outer_product was improved (thanks to rhettinger)
  • The type annotations for sample were improved (thanks to rhettinger)

• Other changes:

  • Python 3.13 is officially supported. Python 3.8 is no longer officially supported. (thanks to hugovk, JamesParrott, and stankudrow)
  • mypy checks were fixed (thanks to JamesParrott)

What's Changed

• Optimize all_equal recipe by @bbayles in #899
• Reduce groupby.next calls in all_equal by @bbayles in #903
• Fix types.UnionType by @bbayles in #905
• Version 10.5.0 by @bbayles in #906

Full Changelog: v10.4.0...v10.5.0

What's Changed

• Issue 854: sample improvements by @bbayles in #855
• Issue 858: Use chain and starmap in run_length.decode by @bbayles in #861
• Issue 859: Update totient recipe by @bbayles in #860
• Distinct permutations of incomparable items by @JamesParrott in #834
• Clarify seekable.relative_seek behavior by @bbayles in #863
• Issue 864: Improve _sample_unweighted by @bbayles in #865
• Use log1p for _sample_unweighted by @bbayles in #868
• Issue 862: change relative_seek() behaviour by @dkrikun in #866
• Issue 876: is_sorted clarifications by @bbayles in #877
• Issue 870: counts parameter for sample by @bbayles in #875
• Issue 869: Add a steps argument to circular_shifts by @bbayles in #874
• Issue 871: Add a fast path for sliding_window by @bbayles in #873
• type annotation of windowed_complete corrected by @m472 in #881
• [Docs] Fix strictly_n missing the n parameter by @fakuivan in #886
• Standardize type hints for isinstance's second argument by @jbosboom in #887
• Issue 883: change type hint by @akisatoon1 in #884
• Add type overloads for zip_broadcast by @Pandede in #888
• Issue 889: Optimize triplewise by @bbayles in #891
• Add option strict to sort_together by @Pandede in #892
• Updates for version 10.4.0 by @bbayles in #893

New Contributors

• @JamesParrott made their first contribution in #834
• @dkrikun made their first contribution in #866
• @m472 made their first contribution in #881
• @fakuivan made their first contribution in #886
• @jbosboom made their first contribution in #887
• @akisatoon1 made their first contribution in #884
• @Pandede made their first contribution in #888

Full Changelog: v10.3.0...v10.4.0

What's Changed

• 100% Code Coverage by @haukex in #792
• Remove recursion from collapse by @james-wasson in #796
• Closes #780: add pre/postpend examples in value_chain doc by @bjrtx in #802
• Increase performance of padded by @james-wasson in #805
• Update table of contents by @bjrtx in #808
• Add exactly size of n doc to padded by @james-wasson in #807
• Speed up ichunked by @james-wasson in #793
• Optimize chunked_even itertool by @james-wasson in #816
• Optimize windowed itertool by @james-wasson in #810
• Issue 822: update iter_index docs by @bbayles in #827
• Issue 823: improve totient by @bbayles in #826
• Issue 821: key argument for all_equal by @bbayles in #825
• Update roundrobin implementation by @bbayles in #829
• Issue 820: add powerset_of_sets by @bbayles in #828
• Fix a typo found by codespell by @DimitriPapadopoulos in #830
• Add typing for countable.items_seen attribute. by @aidanholm in #836
• Add join_mappings by @bbayles in #841
• Add doublestarmap (closes #679) by @monk-time in #845
• Add dft and idft by @bbayles in #847
• Changes for version 10.3.0 by @bbayles in #851
• Add unique() by @bbayles in #850

New Contributors

• @james-wasson made their first contribution in #796
• @bjrtx made their first contribution in #802
• @aidanholm made their first contribution in #836
• @monk-time made their first contribution in #845

Full Changelog: v10.2.0...v10.3.0

• New functions

  • iter_suppress (thanks to jaraco, pochmann, and rhettinger)
  • filter_map (thanks to struktured)
  • classify_unique (thanks to haukex)
  • totient (from the itertools docs)
  • reshape (from the itertools docs)

• Changes to existing functions

  • factor, iter_index, sieve, and unique_justseen were updated to match the itertools docs
  • first was was optimized (thanks to pochmann)
  • takewhile_inclusive was was refactored (thanks to eltoder)
  • combination_with_replacement_index was was optimized (thanks to elliotwutingfeng and rhettinger)
  • nth_permutation, nth_combination_with_replacement, combination_index, and combination_with_replacement_index were optimized (thanks to rhettinger)
  • batched now accepts a strict argument (adapted from itertools docs)
  • time_limited was improved for Windows (thanks to haukex)

• Other changes

  • Several typing updates were made (thanks to obaltian and ilai-deutel)
  • Some documentation issues were fixed (thanks to F-park, DimitriPapadopoulos, peterbygrave, shuuji3, eltoder, and homeworkprod)

What's Changed

• Add more tests for zip_broadcast() by @kalekundert in #739
• Added takewhile_inclusive by @OlegAlexander in #736
• Speed up zip_broadcast() by pre-filling the scalar elements by @kalekundert in #740
• Added outer_product. by @OlegAlexander in #743
• Simplify zip_broadcast by @pochmann in #742
• Simplify _zip_equal by @pochmann in #744
• fix consume() type annotation by @obaltian in #746
• Version 10.1.0 by @bbayles in #747

New Contributors

• @OlegAlexander made their first contribution in #736
• @obaltian made their first contribution in #746

Full Changelog: v10.0.1...v10.1.0