30-seconds-of-code/snippets/difference.md

title, tags, firstSeen, lastUpdated

title	tags	firstSeen	lastUpdated
List difference	list,beginner	2018-01-20T16:16:44+02:00	2020-11-02T19:27:53+02:00

Calculates the difference between two iterables, without filtering duplicate values.

• Create a set from b.
• Use a list comprehension on a to only keep values not contained in the previously created set, _b.

def difference(a, b):
  _b = set(b)
  return [item for item in a if item not in _b]

difference([1, 2, 3], [1, 2, 4]) # [3]