python - if not in list

Question

I have two lists:

mylist = ['total','age','gender','region','sex']
checklist = ['total','civic']

I have to work with some code I have inherited which looks like this:

for item in mylist:
    if item in checklist:
        do something:

How can I work with the code above to tell me that 'civic' is not in mylist?.

This would've been the ideal way to do it but I cant use it, don't ask me why.

for item in checklist:
    if item not in mylist:
        print item

Outcome:

civic

it works for me with Python 2.7. "if item not in mylist" or "if not item in mylist" both works — Jerry T, Oct 20 '15 at 21:12

score 55 · Answer 1 · answered Dec 08 '14 at 21:50

55

Your code should work, but you can also try:

    if not item in mylist :

answered Dec 08 '14 at 21:50

Will

This makes the most logical sense to me and works! Thanks Will - not sure why this is on the bottom. Lets push it up! – embulldogs99 Jun 28 '20 at 02:36

score 13 · Accepted Answer · answered Apr 03 '14 at 09:53

13

How about this?

for item in mylist:
    if item in checklist:
        pass
    else:
       # do something
       print item

answered Apr 03 '14 at 09:53

Santosh Ghimire

2

it works for me with Python 2.7. "if item not in mylist" or "if not item in mylist" both works – Jerry T Oct 20 '15 at 21:12
1

Actually the the preferred syntax is `a not in b` – iRhonin May 21 '18 at 11:31

Yury Wallet · Answer 3 · 2018-06-08T22:16:29.057

3

if I got it right, you can try

for item in [x for x in checklist if x not in mylist]:
    print (item)

edited Jun 08 '18 at 22:16

answered Jun 08 '18 at 21:50

Yury Wallet

score 1 · Answer 4 · edited Oct 13 '16 at 17:50

1

You better do this syntax

if not (item in mylist):  
    Code inside the if

edited Oct 13 '16 at 17:50

Petter Friberg

answered Oct 13 '16 at 17:44

Jose Manuel

7

actually, PEP8 prefers "item not in mylist" over "not item in mylist". https://www.python.org/dev/peps/pep-0008/#programming-recommendations (analogous to "is not" vs "not ... is") – Quantum7 Sep 06 '17 at 15:57

4 Answers4