a.extend(b) better than a+=b ?

candide candide at free.invalid
Thu Apr 22 09:31:12 CEST 2010


Alf P. Steinbach a écrit :
> * candide:
>> Suppose a and b are lists.
>>
>> What is more efficient in order to extend the list a by appending all 
>> the items in the list b ?
>>
>>
>> I imagine a.extend(b)to be more efficient for only appendinding the 
>> items from b while a+=b creates a copy of a before appending, right ?
> 
> No.
> 
> But in general, if you're concerned about efficiency, *measure*.
> 


But my question refers to memory management rather than to time 
execution. Imagine foo is a big size list and bar is a small one. It 
would be a waste of memory to copy list foo somewhere in memory before 
appending the items in bar.



More information about the Python-list mailing list