Python filter a list to only leave objects that occur once

Question

I would like to filter this list,

l = [0,1,1,2,2]

to only leave,

[0].

I\'m struggling to do it in a \'pythoni

Answer 1

In the same spirit as Alex's solution you can use a Counter/multiset (built in 2.7, recipe compatible from 2.5 and above) to do the same thing:

In [1]: from counter import Counter

In [2]: L = [0, 1, 1, 2, 2]

In [3]: multiset = Counter(L)

In [4]: [x for x in L if multiset[x] == 1]
Out[4]: [0]