Getting first n unique elements from Python list

Question

I have a python list where elements can repeat.

>>> a = [1,2,2,3,3,4,5,6]

I want to get the first n unique elements from

Answer 1

Given

import itertools as it


a = [1, 2, 2, 3, 3, 4, 5, 6]

Code

A simple list comprehension (similar to @cdlane's answer).

[k for k, _ in it.groupby(a)][:5]
# [1, 2, 3, 4, 5]

Alternatively, in Python 3.6+:

list(dict.fromkeys(a))[:5]
# [1, 2, 3, 4, 5]