I have a list of lists like this:
i = [[1, 2, 3], [2, 4, 5], [1, 2, 3], [2, 4, 5]] I would like to get a list containing "unique" lists (based on their elements) like:
o = [[1, 2, 3], [2, 4, 5]] I cannot use set() as there are non-hashable elements in the list. Instead, I am doing this:
o = [] for e in i: if e not in o: o.append(e) Is there an easier way to do this?
24 Answers
You can create a set of tuples, a set of lists will not be possible because of non hashable elements as you mentioned.
>>> l = [[1, 2, 3], [2, 4, 5], [1, 2, 3], [2, 4, 5]] >>> set(tuple(i) for i in l) {(1, 2, 3), (2, 4, 5)} i = [[1, 2, 3], [2, 4, 5], [1, 2, 3], [2, 4, 5]] print([ele for ind, ele in enumerate(i) if ele not in i[:ind]]) [[1, 2, 3], [2, 4, 5]] If you consider [2, 4, 5] to be equal to [2, 5, 4] then you will need to do further checks
You can convert each element to a tuple and then insert it in a set.
Here's some code with your example:
tmp = set() a = [[1, 2, 3], [2, 4, 5], [1, 2, 3], [2, 4, 5]] for i in a: tmp.add(tuple(i)) tmp will be like this:
{(1, 2, 3), (2, 4, 5)} Here's another way to do it:
I = [[1, 2, 3], [2, 4, 5], [1, 2, 3], [2, 4, 5]] mySet = set() for j in range(len(I)): mySet = mySet | set([tuple(I[j])]) print(mySet) 
