map is creating a new list of 10,000,000 items, not modifying the values inside list a. That's probably where your time difference comes from...
Jaime On Fri, May 15, 2009 at 1:56 PM, Gediminas Kregzde <gediminas.kreg...@gmail.com> wrote: > Hello, > > I'm Vilnius college II degree student and last semester our teacher > introduced us to python > I've used to program with Delphi, so I very fast adopted to python > > Now I'm developing cross platform program and use huge amounts of > data. Program is needed to run as fast as it coud. I've read all tips > about geting performance, but got 1 bug: map function is slower than > for loop for about 5 times, when using huge amounts of data. > It is needed to perform some operations, not to return data. > > I'm adding sample code: > from time import time > > def doit(i): > pass > > def main(): > a = [0] * 10000000 > t = time() > map(doit, a) > print "map time: " + str(time() - t) > > def main2(): > t = time() > a = [0] * 10000000 > for i in a: > pass > print "loop time: " + str(time() - t) > > main() # takes approximately 5x times longer than main2() > main2() > > I'm wondering were is catch? > > I'm using python 2.6 on windows xp sp2 machine > > P.S. Sorry for my broken English > -- > http://mail.python.org/mailman/listinfo/python-list > -- (\__/) ( O.o) ( > <) Este es Conejo. Copia a Conejo en tu firma y ayúdale en sus planes de dominación mundial. -- http://mail.python.org/mailman/listinfo/python-list
