You use a variation on bucket sort do to this: http://en.wikipedia.org/wiki/Bucket_sort
You make a dict where the keys are the values in the lists, and a name for each list is in the problem. So you get something that looks like: one: list1, list2 two: list1, list2, list3 etc Doing this with collections.defaultdict is a breeze: import collections dd = collections.defaultdict(list) for eachlist in lists: for each in eachlist: dd[each].append(getListName(eachlist)) Then to find the repeated elements you filter where the list is of length > 1. for each in dd: print "%s: %s" % (each, dd[each]) I'd provide code, but I'm not sure what an appropriate naming function is for you, nor am I sure what you're doing with this when you're done. --Michael On Jan 24, 2008 3:15 AM, Fiyawerx <[EMAIL PROTECTED]> wrote: > I have been able to find a few articles on comparing 2 lists, but I have 4 > lists that I need to compare. I need to find any repeated elements and the > list that they came from. For example, > > list1 = ['one', 'two', 'three'] > list2 = ['one', 'two', 'four', 'five'] > list3 = ['two', 'three', 'six', 'seven'] > list4 = ['three', 'five', 'six'] > https://mail.google.com/mail/#label/Pythontutor/117aadf8364dbf3b Gmail - [Tutor] Comparing more than 2 lists - [EMAIL PROTECTED] > > I need to be able to get along the lines of output: > Element 'one' contained in list1 and list2 > Element 'two' contained in list1 and list2 and list3 > ... > Element 'five' contained in list2 and list4 > > etc.. and I can't quite figure out how to go about it > > > _______________________________________________ > Tutor maillist - Tutor@python.org > http://mail.python.org/mailman/listinfo/tutor > > -- Michael Langford Phone: 404-386-0495 Consulting: http://www.RowdyLabs.com _______________________________________________ Tutor maillist - Tutor@python.org http://mail.python.org/mailman/listinfo/tutor