itertools.chain()
itertools.chain() is a Python function in the Itertools Module category. Creates an iterator that returns elements from the first iterable until exhausted, then proceeds to the next. The syntax is itertools.chain(*iterables). Parameters: *iterables — any iterables. Returns: Iterator. A typical example: from itertools import chain
list(chain([1,2], [3,4])) # [1,2,3,4]. A close sibling is itertools.chain.from_iterable(), which alternative chain that takes a single iterable of iterables. A close sibling is itertools.product(), which cartesian product of input iterables (like nested for-loops). A close sibling is itertools.permutations(), which returns all possible r-length ordered arrangements of elements. A close sibling is itertools.combinations(), which returns all r-length unordered combinations without replacement. More about this category: Iterator building blocks — chain, product, permutations, combinations, groupby. For a broader walkthrough, read the Itertools Module guide. Related Itertools Module entries: itertools.chain.from_iterable(), itertools.product(), itertools.permutations(), itertools.combinations(), itertools.combinations_with_replacement(), itertools.cycle(). This page is part of the free Python Reference documentation covering 978+ functions, methods, and modules with examples and parameter details.