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> Date: 2012年9月20日 15:14:36 -0400
> To: docs@python.org
> Subject: [docs] map objects are not lists
>
> 5.1.3. List Comprehensions<http://docs.python.org/dev/tutorial/datastructures.html#list-comprehensions>
>
> List comprehensions provide a concise way to create lists. Common
> applications are to make new lists where each element is the result of some
> operations applied to each member of another sequence or iterable, or to
> create a subsequence of those elements that satisfy a certain condition.
>
> For example, assume we want to create a list of squares, like:
>>>>
>
>>>> squares = []>>> for x in range(10):... squares.append(x**2)...>>> squares[0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
>
> We can obtain the same result with:
>
> squares = [x**2 for x in range(10)]
>
> This is also equivalent to squares = map(lambda x: x**2, range(10)), but
> it?s more concise and readable.
>
>
> I think that the last sentence above should read:
>
> squares = list(map(lambda x: x**2, range(10)))
>
> In other words, the map function returns a map object, not a list object,
> so the list() function needs to be used to convert it to something that is
> truly equivalent to the previous definitions of "squares". (In case it
> matters, I am using Python-3.3.0rc2 on RHEL 6.3.)
(from http://mail.python.org/pipermail/docs/2012-September/010525.html )

Have attached a patch with suggested update.
Have also grepped for similar issues elsewhere in documentation, and haven't found anything, but may have missed something.

2.7 is not affected.

New changeset 6c96878eb729 by Chris Jerdonek in branch '3.2':
Close issue #16073: fix map() example in list comprehension documentation.
http://hg.python.org/cpython/rev/6c96878eb729
New changeset 8a4a88b1e964 by Chris Jerdonek in branch 'default':
Close issue #16073: merge fix from 3.2.
http://hg.python.org/cpython/rev/8a4a88b1e964 

Thanks for helping with the patch and search, Peter.