[portland] Sorting A List of Tuples

[kirby urner]

Hi Rich --

The list.sort() method takes an optional 'key' argument that'd be a
function, which you might use to pick out the value you want to
compare, as follows:

IDLE 1.2.1

>>> mylist = [(1,2,3), (8,1,7), (8,5,2)]

>>> def f(x):
	return x[1]

>>> mylist.sort(key=f)
>>> mylist
[(8, 1, 7), (1, 2, 3), (8, 5, 2)]

Or just use lambda in this case:

>>> mylist = [(1,2,3), (8,1,7), (8,5,2)]
>>> mylist.sort(key=lambda x: x[1])
>>> mylist
[(8, 1, 7), (1, 2, 3), (8, 5, 2)]

Kirby


On Nov 8, 2007 9:25 AM, Rich Shepard <rshepard at appl-ecosys.com> wrote:
>    All the information I find on sorting lists assumes the list has only a
> single value to be sorted. What to do with multiple values when the sort is
> on the second or third item and all must be kept together?
>
>    I have lists of tuples which I'd like to sort on the second item while
> retaining the relationships among the item pairs.
>
>    Could I do
>         terms.sort([][1])
> ?
>
>    A pointer to a reference would be fine.
>
> Rich
>
> --
> Richard B. Shepard, Ph.D.               |  Integrity            Credibility
> Applied Ecosystem Services, Inc.        |            Innovation
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