substituting list comprehensions for map()
J Kenneth King
james at agentultra.com
Mon Nov 2 14:45:28 CET 2009
Steven D'Aprano <steven at 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
>> 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.
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