[Tutor] Newbie: Sorting lists of lists

[Forrest Y. Yu]

>
> Message: 8
> Date: Wed, 18 Jun 2008 19:30:05 -0500
> From: Keith Troell <ktroell at mac.com>
> Subject: [Tutor] Newbie: Sorting lists of lists
> To: tutor at python.org
> Message-ID: <2AAF54E8-95D9-4CB3-BD1E-CA2270E4B165 at mac.com>
> Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed
>
> Let's say I have a list of lists l == [[1, 2, 3], [2, 3, 1], [3, 2,
> 1], [1, 3, 2]]
>
> If I do a l.sort(), it sorts on the first element of each listed list:
>
>  >>> l.sort()
>  >>> l
> [[1, 2, 3], [1, 3, 2], [2, 3, 1], [3, 2, 1]]
>
>
> How can I sort on the second or third elements of the listed lists?


I know, it's NOT beautiful code, but it seems work. If you have no better
way, try this:

"""Sort on the second elements."""
def xchg12(l) :
    for m in l:
        m[0], m[1] = m[1], m[0]

l = [[1, 2, 3], [2, 3, 1], [3, 2,1], [1, 3, 2]]
print l
xchg12(l)
l.sort()
xchg12(l)
print l

Yuan (yet unlovely another newbie)


>
> Keith
>
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>
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