How to change a value if it is in 2 lists in python with matching index

Question

If I have

list1 = [1, 2, 3, 6]
list2 = [4, 3, 5, 6]

how can I change the values of anything that matches between the two list? Only if the Index also matches

the desired output is

list1 = [1, 2, 3, 'match']

I was using this

for idx,x in enumerate(list1):
    if x in list2:  
        list1[idx] = 'match'

But this replaces the 3 and the 6

Try `["match" if i in list2 else i for i in list1]`? – Chris Jul 08 '20 at 11:36 — Chris, Jul 08 '20 at 11:36

orestisf · Accepted Answer · 2020-07-08T11:42:20.777

0

Your code does not work because you are re-assigning to the x variable, not changing it's content. If you want a for-loop you can try this:

for idx,x in enumerate(list1):
    if x in list2:  # Assuming you meant list2 here instead of list1
        list1[idx] = 'match'

alternatively, a more "pythonic" way (from the comments) is:

list1 = ["match" if i in list2 else i for i in list1]

edited Jul 08 '20 at 11:42

answered Jul 08 '20 at 11:38

orestisf

Well, being the first to answer with a typo in a non-working code is really not useful... Please take your time to read the question and test your code. – Thierry Lathuille Jul 08 '20 at 11:39
Sorry, I didn't notice the typo in the original code – orestisf Jul 08 '20 at 11:40
2

There still is a typo, and your code still doesn't work. – Thierry Lathuille Jul 08 '20 at 11:41
3

And then reposting the comment of someone else as your answer, doesn't add much. – Ronald Jul 08 '20 at 11:42
Adding comments in an answer, especially when it is a complimentary alternative, is not against the rules or frowned upon. See here: https://meta.stackoverflow.com/questions/304126/is-it-correct-to-answer-copying-from-comments-by-other-users – orestisf Jul 08 '20 at 11:46

1 Answers1