Steven D'Aprano schrieb:
On Sun, 01 Nov 2009 23:54:16 -0800, Jon P. wrote:
I'd like to do:
resultlist = operandlist1 + operandlist2
where for example
operandlist1=[1,2,3,4,5]
operandlist2=[5,4,3,2,1]
and resultlist will become [6,6,6,6,6]. Using map(), I can do:
map(lambda op1,op2: op1 + op2, operandlist1, operandlist2)
If the two lists are very large, it would be faster to use this:
from operator import add
map(add, operandlist1, operandlist2)
Is there any reasonable way to do this via a list comprehension ?
[x+y for (x, y) in zip(operandlist1, operandlist2)]
If the lists are huge, you can save some temporary memory by replacing
zip with itertools.izip.
And even more so if one needs the results one by one - then just use a
generator-expression.
Diez
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