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bpo-30538: Update count() in Functional Programming HOWTO (#1919) 

* bpo-30538: Update count() in Functional HOWTO

* bpo-30538: Update enumerate() arguments in Functional HOWTO
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csabella 2017-06-04 13:39:21 -04:00 committed by Raymond Hettinger
parent 5de3a64179
commit 9be4ff359d
1 changed files with 14 additions and 9 deletions
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Doc/howto/functional.rst
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@ -653,8 +653,9 @@ This can also be written as a list comprehension:
[0, 2, 4, 6, 8] [0, 2, 4, 6, 8]
:func:`enumerate(iter) <enumerate>` counts off the elements in the iterable, :func:`enumerate(iter, start=0) <enumerate>` counts off the elements in the
returning 2-tuples containing the count and each element. :: iterable returning 2-tuples containing the count (from *start*) and
each element. ::
>>> for item in enumerate(['subject', 'verb', 'object']): >>> for item in enumerate(['subject', 'verb', 'object']):
... print(item) ... print(item)
@ -747,14 +748,16 @@ The module's functions fall into a few broad classes:
Creating new iterators Creating new iterators
---------------------- ----------------------
:func:`itertools.count(n) <itertools.count>` returns an infinite stream of :func:`itertools.count(start, step) <itertools.count>` returns an infinite
integers, increasing by 1 each time. You can optionally supply the starting stream of evenly spaced values. You can optionally supply the starting number,
number, which defaults to 0:: which defaults to 0, and the interval between numbers, which defaults to 1::
itertools.count() => itertools.count() =>
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, ... 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, ...
itertools.count(10) => itertools.count(10) =>
10, 11, 12, 13, 14, 15, 16, 17, 18, 19, ... 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) <itertools.cycle>` saves a copy of the contents of :func:`itertools.cycle(iter) <itertools.cycle>` saves a copy of the contents of
a provided iterable and returns a new iterator that returns its elements from 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]: for i in [1,2,3]:
product *= i product *= i
A related function is `itertools.accumulate(iterable, func=operator.add) <itertools.accumulate`. A related function is :func:`itertools.accumulate(iterable, func=operator.add)
It performs the same calculation, but instead of returning only the <itertools.accumulate>`. It performs the same calculation, but instead of
final result, :func:`accumulate` returns an iterator that also yields returning only the final result, :func:`accumulate` returns an iterator that
each partial result:: also yields each partial result::
itertools.accumulate([1,2,3,4,5]) => itertools.accumulate([1,2,3,4,5]) =>
1, 3, 6, 10, 15 1, 3, 6, 10, 15
@ -1235,6 +1238,8 @@ Python documentation
Documentation for the :mod:`itertools` module. Documentation for the :mod:`itertools` module.
Documentation for the :mod:`functools` module.
Documentation for the :mod:`operator` module. Documentation for the :mod:`operator` module.
:pep:`289`: "Generator Expressions" :pep:`289`: "Generator Expressions"