From: csabella Date: Mon, 5 Jun 2017 03:11:58 +0000 (-0400) Subject: bpo-30538: Update count() in Functional Programming HOWTO (GH-1919) (GH-1944) X-Git-Tag: v3.5.4rc1~110 X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=b32fb6c1fb6cdf019817176f573e60c0923a6e22;p=python bpo-30538: Update count() in Functional Programming HOWTO (GH-1919) (GH-1944) * bpo-30538: Update count() in Functional HOWTO * bpo-30538: Update enumerate() arguments in Functional HOWTO (cherry picked from commit 9be4ff359daa67cde6246494f643ed7cd2825d46) --- diff --git a/Doc/howto/functional.rst b/Doc/howto/functional.rst index a82dca7077..40601812a7 100644 --- a/Doc/howto/functional.rst +++ b/Doc/howto/functional.rst @@ -653,8 +653,9 @@ This can also be written as a list comprehension: [0, 2, 4, 6, 8] -:func:`enumerate(iter) ` counts off the elements in the iterable, -returning 2-tuples containing the count and each element. :: +:func:`enumerate(iter, start=0) ` counts off the elements in the +iterable returning 2-tuples containing the count (from *start*) and +each element. :: >>> for item in enumerate(['subject', 'verb', 'object']): ... print(item) @@ -747,14 +748,16 @@ The module's functions fall into a few broad classes: Creating new iterators ---------------------- -:func:`itertools.count(n) ` returns an infinite stream of -integers, increasing by 1 each time. You can optionally supply the starting -number, which defaults to 0:: +:func:`itertools.count(start, step) ` returns an infinite +stream of evenly spaced values. You can optionally supply the starting number, +which defaults to 0, and the interval between numbers, which defaults to 1:: itertools.count() => 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, ... itertools.count(10) => 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, ... + itertools.count(10, 5) => + 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, ... :func:`itertools.cycle(iter) ` saves a copy of the contents of a provided iterable and returns a new iterator that returns its elements from @@ -1060,10 +1063,10 @@ write the obvious :keyword:`for` loop:: for i in [1,2,3]: product *= i -A related function is `itertools.accumulate(iterable, func=operator.add) `. It performs the same calculation, but instead of +returning only the final result, :func:`accumulate` returns an iterator that +also yields each partial result:: itertools.accumulate([1,2,3,4,5]) => 1, 3, 6, 10, 15 @@ -1235,6 +1238,8 @@ Python documentation Documentation for the :mod:`itertools` module. +Documentation for the :mod:`functools` module. + Documentation for the :mod:`operator` module. :pep:`289`: "Generator Expressions"