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
