Hey Bruno...you are seeing the wrong post :P...please ignore this and check out the one with (corrected) appended at the end... Also, i used the list comprehension thingy which u have given, but now the problem is python just hangs if my list l4 contains around 50 pairs...considering its not that big a data, this shouldnt happen.... Should it??
> Girish Sahani wrote: >> Hi, >> I am trying to convert a list of pairs (l4) to list l5 by removing >> those >> pairs from l4 which are not present in a third list called pairList. > > > > >> The following is a simplified part of the routine i have written. >> However >> it does not give the correct output. Please help! >> Its possible i have made a trivial mistke since i am a newbie. >> >> def getl5(): > <ot> > Please avoid this kind of names : it's both meaningless (what the ... is > 'l5', I wonder ???) and confusing (is it 'l5' or '15' ?) > > FWIW, read this: > http://mindprod.com/jgloss/unmain.html > </ot> >> l5 = [] >> pairList = [[1,2],[3,4],[3,5],[3,6],[9,7],[8,9],[8,7],[7,9],[11,10]] > >>From a semantic POV, you should use tuples for pairs - not lists. > >> l4 = >> [[4,2],[4,7],[4,10],[4,12],[9,2],[9,7],[9,10],[9,12],[11,2],[11,7]] >> for pair in l4: >> if pair not in pairList: > err... see below... >> element.remove(l4) >> l5.append(element) > This is outside the for loop, so this would be executed only once (if > the rest of the code was correct, of course...) > >> print "l5 is",l5 >> > > You did not test this code, did you ? > >>>> getl5() > Traceback (most recent call last): > File "<stdin>", line 1, in ? > File "/usr/tmp/python-961l_S.py", line 7, in getl5 > NameError: global name 'element' is not defined >>>> > > The SimpleStupid(tm) way to do this is far more simple - at least if I > understood your specifications: > > pairList = [(1,2),(3,4),(3,5),(3,6),(9,7),(8,9),(8,7),(7,9),(11,10)] > l4 = [(4,2),(4,7),(4,10),(4,12),(9,2),(9,7),(9,10),(9,12),(11,2),(11,7)] > l5 = [pair for pair in l4 if pair in pairList] > print "l5 is : ", l5 > > Now this is not necessarily the most efficient solution... > > -- > bruno desthuilliers > python -c "print '@'.join(['.'.join([w[::-1] for w in p.split('.')]) for > p in '[EMAIL PROTECTED]'.split('@')])" > -- > http://mail.python.org/mailman/listinfo/python-list > -- http://mail.python.org/mailman/listinfo/python-list
