Gerard Flanagan wrote: > Rob Cowie wrote: > > I'm having a bit of trouble with this so any help would be gratefully > > recieved... > > > > After splitting up a url I have a string of the form > > 'tag1+tag2+tag3-tag4', or '-tag1-tag2' etc. The first tag will only be > > preceeded by an operator if it is a '-', if it is preceded by nothing, > > '+' is to be assumed. > > > > Using re.split, I can generate a list that looks thus: > > ['tag1', '+', 'tag2', '+', 'tag3', '-', 'tag4'] > > > > I wish to derive two lists - each containing either tags to be > > included, or tags to be excluded. My idea was to take an element, > > examine what element precedes it and accordingly, insert it into the > > relevant list. However, I have not been successful. > > > > Is there a better way that I have not considered? If this method is > > suitable, how might I implement it? > > > > Thanks all, > > > > Rob Cowie > > a = [ '+', 'tag1', '+', 'tag2', '-', 'tag3', '+', 'tag4' ] > > import itertools > > b = list(itertools.islice(a,0,8,2)) > c = list(itertools.islice(a,1,8,2)) > > result1 = [x[1] for x in itertools.izip(b,c) if x[0] == '+'] > result2 = [x[1] for x in itertools.izip(b,c) if x[0] == '-'] > > print > print result1 > print result2 > > > Gerard
'8' is the length of 'a' (len(a)) -- http://mail.python.org/mailman/listinfo/python-list
