Steven D'Aprano <ste...@remove.this.cybersource.com.au> writes: > 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)
This is the best solution so far. > > >> 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. I understand the OP was asking for it, but list comprehensions aren't the best solution in this case... it would just be line noise. List comprehensions are good for one-off transformations where it would only create a one-time method for map to use. -- http://mail.python.org/mailman/listinfo/python-list
