How to remove duplicate lists in a list of list? [duplicate]

Solution 1:

You could use a set:

b_set = set(map(tuple,a))  #need to convert the inner lists to tuples so they are hashable
b = map(list,b_set) #Now convert tuples back into lists (maybe unnecessary?)

Or, if you prefer list comprehensions/generators:

b_set = set(tuple(x) for x in a)
b = [ list(x) for x in b_set ]

Finally, if order is important, you can always sort b:

b.sort(key = lambda x: a.index(x) )

Solution 2:

See mgilson's answer if the order of the lists is not important. If you want to retain the order, do something like:

b = list()
for sublist in a:
    if sublist not in b:
        b.append(sublist)

This will keep the order in the original list. However, it is slower and more verbose than using sets.