On Apr 21, 4:16 pm, George Sakkis <[EMAIL PROTECTED]> wrote: > On Apr 21, 4:42 pm, Matimus <[EMAIL PROTECTED]> wrote: > > > > > On Apr 21, 12:05 pm, <[EMAIL PROTECTED]> wrote: > > > > I've been trying to figure out a way to combine lists similar to how > > > zip() works. The main > > > difference though is I want to work with different length lists and > > > combine them. I came up with > > > the example below, which returns a list like I'm wanting. I'm assuming > > > it's somewhat efficient > > > (although I wonder if the lists were huge that the 'if' statement might > > > slow things down?). > > > > If anyone has time, I was wondering if you could share your thoughts on > > > whether this is an > > > efficient way to do something like this, if it's horrible and slow, etc. > > > > Thanks! > > > > Jay > > > > # ---------------------------- > > > > def combineLists(theLists): > > > cntList = len(theLists) > > > lenList = [len(x) for x in theLists] > > > > maxList = max(lenList) > > > > combinedList = [] > > > > for x in range(maxList): > > > for n in range(cntList): > > > if lenList[n] > x: combinedList.append(theLists[n][x]) > > > > print combinedList > > > > combineLists([a, b, c]) > > > > # ---------------------------- > > > > # --> ['a', '1', 'a1', 'b', '2', 'b2', 'c', 'c3', 'd4', 'e5'] > > > I would probably do something like this: > > > >>> def combine(*seqs): > > > ... seqs = [iter(s) for s in seqs] > > ... while seqs: > > ... for g in seqs: > > ... try: > > ... yield g.next() > > ... except StopIteration: > > ... seqs.remove(g) > > ...>>> a = 'abc' > > >>> b = '12' > > >>> c = 'a1 b2 c3 d4 e5'.split() > > >>> list(combine(a,b,c)) > > > ['a', '1', 'a1', 'b', '2', 'b2', 'c', 'c3', 'd4', 'e5'] > > > It has the advantage that it uses the generator protocol, so you can > > pass in any type of sequence. It uses arbitrary arguments to make its > > use closer to that of zip. It is also a generator, so it takes > > advantage of lazy evaluation. Notice that there is never any checking > > of length. > > > Matt > > A similar solution using the itertools > module:http://aspn.activestate.com/ASPN/Cookbook/Python/Recipe/528936 > > George
Very nice. I was wondering if there would be a way to pull that try/ except block outside of the for loop. Jay: use this solution. It has all of the advantages I list for my solution, only it should be faster, and lazier. Matt -- http://mail.python.org/mailman/listinfo/python-list
