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Forgive me, and be kind, as I am just a newby learning this language
out of M.L. Hetland's book. The following behavior of 2.4.1 seems very
strange
>>> x = ['aardvark', 'abalone', 'acme', 'add',
'aerate']
>>> x.sort(key=len)
>>> x
['add', 'acme', 'aerate', 'abalone', 'aardvark']
>>> x.sort(reverse=True)
>>> x
['aerate', 'add', 'acme', 'abalone', 'aardvark']
The function called on line 4, at least to me, should work on x as it
was on line 3, not the previously existing x on line 1. What gives?
By the way these functions do not exist in 2.3.5 so they must be newly
implemented.

On 11 Nov 2005 11:34:47 -0800, Greg <> wrote:
> Forgive me, and be kind, as I am just a newby learning this language
> out of M.L. Hetland's book. The following behavior of 2.4.1 seems very
> strange
> >>> x = ['aardvark', 'abalone', 'acme', 'add',
> 'aerate']
> >>> x.sort(key=len)
> >>> x
> ['add', 'acme', 'aerate', 'abalone', 'aardvark']
> >>> x.sort(reverse=True)
> >>> x
> ['aerate', 'add', 'acme', 'abalone', 'aardvark']
> The function called on line 4, at least to me, should work on x as it
> was on line 3, not the previously existing x on line 1. What gives?

The key option defaults to an alphabetic sort *every time* you call
sort, so if you want to change this, you must call for your sort key
each time. To do what you want, roll the sorts into one step:

>>> x.sort(key=len, reverse=True)
>>> x
['aardvark', 'abalone', 'aerate', 'acme', 'add']


--
Kristian

kristian.zoerhoff(AT)gmail.com
zoerhoff(AT)freeshell.org

On 2005-11-11, Kristian Zoerhoff <> wrote:
> On 11 Nov 2005 11:34:47 -0800, Greg <> wrote:
>> Forgive me, and be kind, as I am just a newby learning this language
>> out of M.L. Hetland's book. The following behavior of 2.4.1 seems very
>> strange
>> >>> x = ['aardvark', 'abalone', 'acme', 'add',
>> 'aerate']
>> >>> x.sort(key=len)
>> >>> x
>> ['add', 'acme', 'aerate', 'abalone', 'aardvark']
>> >>> x.sort(reverse=True)
>> >>> x
>> ['aerate', 'add', 'acme', 'abalone', 'aardvark']
>> The function called on line 4, at least to me, should work on x as it
>> was on line 3, not the previously existing x on line 1. What gives?
>
> The key option defaults to an alphabetic sort *every time* you call
> sort, so if you want to change this, you must call for your sort key
> each time. To do what you want, roll the sorts into one step:
>
>>>> x.sort(key=len, reverse=True)
>>>> x
> ['aardvark', 'abalone', 'aerate', 'acme', 'add']
>
>


.... or just reverse it after:

>>> x.sort(key=len)
>>> x.reverse()
>>> x
['aardvark', 'abalone', 'aerate', 'acme', 'add']

On Fri, 11 Nov 2005 11:34:47 -0800, Greg wrote:

> Forgive me, and be kind, as I am just a newby learning this language
> out of M.L. Hetland's book. The following behavior of 2.4.1 seems very
> strange

>>>> x = ['aardvark', 'abalone', 'acme', 'add', 'aerate']
>>>> x.sort(key=len)
>>>> x
> ['add', 'acme', 'aerate', 'abalone', 'aardvark']
>>>> x.sort(reverse=True)
>>>> x
> ['aerate', 'add', 'acme', 'abalone', 'aardvark']

> The function called on line 4, at least to me, should work on x as it
> was on line 3, not the previously existing x on line 1. What gives?

Why do you think it isn't operating on x as it is? The second sort is
sorting in reverse lexicographic order, which is the result you get.

I'm not running Python 2.4 so I can't test this, but to get the result you
want I guess you want this:

py> x.sort(key=len, reverse=True)
py> x
['aardvark', 'abalone', 'aerate', 'acme', 'add']

or:

py> x.sort(key=len)
py> x.reverse()


--
Steven.