Removing the common elements between two lists

Question

Possible Duplicate:
Python list subtraction operation

I want to remove the common elements between two lists. I mean something like this

a=[1,2,3,4,5,6,7,8]
b=[2,4,1]
# I want the result to be like
res=[3,5,6,7,8]

Is there any simple pythonic way to do this ?

What have you got till now? – Rohit Jain Dec 02 '12 at 18:53 — Rohit Jain, Dec 02 '12 at 18:53

score 49 · Accepted Answer · answered Dec 02 '12 at 18:57

49

use sets :

res = list(set(a)^set(b))

answered Dec 02 '12 at 18:57

dugres

10

You should note that this loses ordering and any duplicates in either list. If OP doesn't mind that, though, it's the sexiest solution. – Russell Borogove Dec 02 '12 at 19:24
3

Awesome! What's the `^` operand meaning in this case? – fabio.sang May 26 '19 at 09:33
1

^ here means disjoint. – Konchog Jul 01 '20 at 13:41
keep in mind that results contains uncommon elements from b. for ex : a = [1,2,3,4,5] and b = [1,2,8] the result is : [3,4,5,8] – Saeid Mohammadi Nejati Jul 18 '23 at 18:09

score 12 · Answer 2 · edited Jan 21 '20 at 12:23

12

You can use sets learn more from here

print(set(a).difference(b))

edited Jan 21 '20 at 12:23

Caleb Njiiri

answered Dec 02 '12 at 20:09

1

`list(set(a).difference(b))` make ordered list. What if i donot want ordered list and want same as list a, just removed common elements – Hitesh May 30 '18 at 11:26
7

may be `x = [i for i in x if i not in y] ` good choice. – Hitesh May 30 '18 at 11:44
3

This doesn't quite answer the OP as stated... but this DOES answer the question I was actually looking for, and is a useful answer. This returns only the elements of a that are not in b (OP asked for non-dupe elements in both a and b) – G__ Oct 27 '18 at 04:24

2 Answers2