[docs] [issue16077] fix code example in docs for built-in reduce()

Chris Jerdonek report at bugs.python.org
Fri Sep 28 10:55:52 CEST 2012


New submission from Chris Jerdonek:

> Date: Thu, 6 Sep 2012 20:38:21 +0800
> To: docs at python.org
> Subject: [docs] There is bug about the built-in function reduce in the
>         document
>
> I found a bug in the document about reduce :
> http://docs.python.org/library/functions.html#reduce
>
> Here is the patch:
> def reduce(function, iterable, initializer=None):
>     it = iter(iterable)
>     if initializer is None:
>         try:
>             initializer = next(it)
>         except StopIteration:
>             raise TypeError('reduce() of empty sequence with no initial
> value')
>     accum_value = initializer
> -    for x in iterable:
> +   for x in it:
>         accum_value = function(accum_value, x)
>     return accum_value
>
> It duplicated the first element of iterable
>
> For example:
> In [4]: reduce(lambda x,y:x+y, [1,2,3,4])
> Out[4]: 10
>
> In [5]: docreduce.reduce(lambda x,y:x+y ,[1,2,3,4])
> Out[5]: 11

(from: http://mail.python.org/pipermail/docs/2012-September/010513.html and
  http://mail.python.org/pipermail/docs/2012-September/010526.html )

----------
assignee: docs at python
components: Documentation
keywords: easy
messages: 171419
nosy: chris.jerdonek, docs at python
priority: normal
severity: normal
stage: needs patch
status: open
title: fix code example in docs for built-in reduce()
type: enhancement
versions: Python 2.7

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue16077>
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