list.sort()

Charlie Dyson charlie at charliedyson.net
Sun Jun 17 22:13:24 CEST 2001


William Park - opengeometry at yahoo.ca wrote on Sunday 17 June 2001 17:58:

> On Sun, Jun 17, 2001 at 07:42:09PM +0200, Rikard Bosnjakovic wrote:
>> >>> l = l.sort()
>> >>> l
>> >>> print l
>> None
>> 
>> If we split the problem into parts, "l.sort()" sorts l and it becomes
>> [2,3,4]. I expected it to be [2,3,4] after assigning it to itself (after
>> it got sorted), but the list seem to got deleted instead. I don't like
>> this behaviour, at all.
> 
> 'l.sort()' returns 'None', and you are assigning this 'None' back to
> 'l'.  Instead, try
>     >>> l.sort()
>     >>> print l
> 
>> Why does Python behave like this? Why does sort() change lists
>> _in-place_, instead of returning a list?
> 
> Efficiency.
> 

Hmm, I actually think that this behaviour is not very logical. Concider:

x = {'Python' : 'Cool', 'Linux' : 'Cool'}
print x.keys().sort() # Prints None

It would be better if it sort **returned** the results, instead I have to 
do:
keys = x.keys()
keys.sort()

That's one extra line of code!!!

Anyway, I get on with Python better than I get on with other languages I 
must not mention in order to avert a flame-war.

Charlie Dyson - charlie at charliedyson.net




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