Question

So I’m relatively new to Python and trying to figure out what’s the best way to keep only unique items in a list. My current implementation involves a Counter, dict and list comprehensions, but I’m not sure what may be faster.

Here’s an example of what I’ve tried:

l = ['a', 'b', 'a']
d = dict(Counter(l))
[key for key, val in d.items() if val == 1]
>>> ['b']

Also, this only works for strings and not ints and I’m not sure why.

Answer 1

Do you want only things that exist one time?

>>> c=Counter(['a','b','a'])
>>> [n for n in c if c[n]==1]
['b']
>>> c=Counter([1,2,3,2,3,4,5,6,5,6])
>>> [n for n in c if c[n]==1]
[1, 4]

Or just a list of unique things?

>>> set([1,2,3,2,3,4,5,6,5,6])
set([1, 2, 3, 4, 5, 6])