Python Itertools Module
Iterator building blocks — chain, product, permutations, combinations, groupby. This category documents 18 Python itertools module entries, and each page gives you the full syntax, the parameter list, the return value, and a runnable example. The entries include: itertools.chain(), itertools.chain.from_iterable(), itertools.product(), itertools.permutations(), itertools.combinations(), itertools.combinations_with_replacement(), itertools.cycle(), itertools.repeat(), itertools.accumulate(), itertools.groupby(), itertools.starmap(), itertools.filterfalse(), itertools.compress(), itertools.count(), itertools.islice(), itertools.tee(), itertools.zip_longest(), itertools.pairwise(). itertools.chain() creates an iterator that returns elements from the first iterable until exhausted, then proceeds to the next. itertools.chain.from_iterable() alternative chain that takes a single iterable of iterables. itertools.product() cartesian product of input iterables (like nested for-loops). itertools.permutations() returns all possible r-length ordered arrangements of elements. itertools.combinations() returns all r-length unordered combinations without replacement. For a structured walkthrough of the whole topic, read the Itertools Module guide. Itertools Module belongs to the Collections & Iteration group alongside Collections Module, Functools Module, Operator Module, Bisect Module.