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gh-135282: change documented signature of itertools.accumulate() #135283

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gh-135282: correct itertools.accumulate() signature in sphinx docs
skirpichev Jun 9, 2025
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+ example
skirpichev Jun 9, 2025
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16 changes: 8 additions & 8 deletions Doc/library/itertools.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -93,12 +93,12 @@ streams of infinite length, so they should only be accessed by functions or
loops that truncate the stream.


.. function:: accumulate(iterable[, function, *, initial=None])
.. function:: accumulate(iterable, func=None, *, initial=None)

Make an iterator that returns accumulated sums or accumulated
results from other binary functions.

The *function* defaults to addition. The *function* should accept
The *func* defaults to addition. The *func* should accept
two arguments, an accumulated total and a value from the *iterable*.

If an *initial* value is provided, the accumulation will start with
Expand All @@ -107,7 +107,7 @@ loops that truncate the stream.

Roughly equivalent to::

def accumulate(iterable, function=operator.add, *, initial=None):
def accumulate(iterable, func=operator.add, *, initial=None):
'Return running totals'
# accumulate([1,2,3,4,5]) → 1 3 6 10 15
# accumulate([1,2,3,4,5], initial=100) → 100 101 103 106 110 115
Expand All @@ -123,12 +123,12 @@ loops that truncate the stream.

yield total
for element in iterator:
total = function(total, element)
total = func(total, element)
yield total

To compute a running minimum, set *function* to :func:`min`.
For a running maximum, set *function* to :func:`max`.
Or for a running product, set *function* to :func:`operator.mul`.
To compute a running minimum, set *func* to :func:`min`.
For a running maximum, set *func* to :func:`max`.
Or for a running product, set *func* to :func:`operator.mul`.
To build an `amortization table
<https://www.ramseysolutions.com/real-estate/amortization-schedule>`_,
accumulate the interest and apply payments:
Expand All @@ -152,7 +152,7 @@ loops that truncate the stream.
.. versionadded:: 3.2

.. versionchanged:: 3.3
Added the optional *function* parameter.
Added the optional *func* parameter.

.. versionchanged:: 3.8
Added the optional *initial* parameter.
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