Question

I would like to filter this list,

[0, 1, 1, 2, 2]

to only leave

[0]

I’m struggling to do it in a ‘pythonic’ way. Is it possible without nested loops?

Answer 1

Here’s another dictionary oriented way:

l = [0, 1, 1, 2, 2]
d = {}
for i in l: d[i] = i in d

[k for k in d if not d[k]]  # unordered, loop over the dictionary
[k for k in l if not d[k]]  # ordered, loop over the original list