for(each) element aliasing

Reinhold Birkenfeld reinhold-birkenfeld-nospam at
Mon Nov 22 19:34:01 CET 2004

Matija Papec wrote:
> X-Ftn-To: Jp Calderone 
> Jp Calderone <exarkun at> wrote:
>>> -------
>>> 2 4 6
>>  No.  Integers in Python are immutable.  For lists of other things, mutation in-place (similar to the above example) is possible, but for integers and other immutable types, it is not.  You may be interested in list comprehensions, though:
>>    arr = range(1, 4)
>>    arr[:] = [a * 2 for a in arr]
>>    print arr
> I guess this works like "map" but "for" is more idimatic.

Yes. List comprehensions are elegant (and fast) expressions you would
otherwise construct with map() and filter().


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