John Salerno a écrit :
> John Salerno wrote:
>
>> Bruno Desthuilliers wrote:
>>
>>> John Salerno a écrit :
>>>
>>>> Hi everyone. If I have a list of tuples, and each tuple is in the form:
>>>>
>>>> (year, text) as in ('1995', 'This is a citation.')
>>>>
>>>> How can I sort the list so that they are in chronological order
>>>> based on the year?
>>>
>>>
>>> Calling sort() on the list should just work.
>>
>>
>> Amazing, it was that easy. :)
>
>
> One more thing. What if I want them in reverse chronological order? I
> tried reverse() but that seemed to put them in reverse alphabetical
> order based on the second element of the tuple (not the year).
Really ?
>>> lines = [('1995', 'aaa'), ('1997', 'bbb'), ('1995', 'bbb'),
('1997', 'aaa'), ('1995', 'ccc'), ('1996', 'ccc'), ('1996', 'aaa')]
>>> lines.sort()
>>> lines
[('1995', 'aaa'), ('1995', 'bbb'), ('1995', 'ccc'), ('1996', 'aaa'),
('1996', 'ccc'), ('1997', 'aaa'), ('1997', 'bbb')]
>>> lines.reverse()
>>> lines
[('1997', 'bbb'), ('1997', 'aaa'), ('1996', 'ccc'), ('1996', 'aaa'),
('1995', 'ccc'), ('1995', 'bbb'), ('1995', 'aaa')]
>>>
As you see, the list is being sorted on *both* items - year first, then
sentence. And then of course reversed, since we asked for it !-)
If you want to prevent this from happening and don't mind creating a
copy of the list, you can use the sorted() function with the key and
reverse arguments and operator.itemgetter:
>>> lines = [('1995', 'aaa'), ('1997', 'bbb'), ('1995', 'bbb'),
('1997', 'aaa'), ('1995', 'ccc'), ('1996', 'ccc'), ('1996', 'aaa')]
>>> from operator import itemgetter
>>> sorted(lines, key=itemgetter(0), reverse=True)
[('1997', 'bbb'), ('1997', 'aaa'), ('1996', 'ccc'), ('1996', 'aaa'),
('1995', 'aaa'), ('1995', 'bbb'), ('1995', 'ccc')]
HTH.
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