On Thu, 11 Jan 2007 06:06:39 -0800, [EMAIL PROTECTED] wrote: >> [EMAIL PROTECTED] wrote: >> > Hi, >> > Frequently I get to do like this: >> > a = (1, 2, 3, 4) # some dummy values >> > b = (4, 3, 2, 1) >> > import operator >> > c = map(operator.add, a, b) >> > >> > I am finding the last line not very readable especially when I combine >> > couple of such operations into one line. Is it possible to overload >> > operators, so that, I can use .+ for element wise addition, as, >> > c = a .+ b >> > which is much more readable.
[snip] > I just found this from : > http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/384122 > > class Infix(object): [snip code] > c = a |dotplus| b Personally, I find that to be the least readable of all the alternatives. It is also slow, so slow that using it is (in my opinion) a pessimation rather than an optimization. Let me make the usual warnings about premature optimization being the root of all evil, blah blah blah. Readability counts, and nobody cares if you shave one hundredth of a millisecond off some code that your program runs once. But, having said that, map is *fast*, especially with the functions from operator. >>> import timeit >>> timeit.Timer("map(operator.add, a, b)", ... "import operator; a = (1, 2, 3, 4); b = (4, 3, 2, 1)").timeit() 4.0072550773620605 It is even faster if you get rid of the dot lookup: >>> timeit.Timer("map(add, a, b)", "from operator import add; " ... "a = (1, 2, 3, 4); b = (4, 3, 2, 1)").timeit() 3.6557090282440186 Using lambda can be much slower: >>> timeit.Timer("map(lambda x,y: x+y, a, b)", ... "a = (1, 2, 3, 4); b = (4, 3, 2, 1)").timeit() 6.1221940517425537 A list comprehension is in the middle, speed-wise: >>> timeit.Timer("[x+y for x,y in zip(a,b)]", ... "a = (1, 2, 3, 4); b = (4, 3, 2, 1)").timeit() 5.0318419933319092 But the Infix recipe is slower than a wet week: >>> timeit.Timer("a|dotplus|b", ... "a = (1, 2, 3, 4); b = (4, 3, 2, 1); " ... "from __main__ import dotplus").timeit() 15.195909976959229 Speaking for myself, I find list comprehensions to be the most readable of the alternatives and the most Pythonic. -- Steven. -- http://mail.python.org/mailman/listinfo/python-list
