Python Language List Checking whether an item is in a list


Python makes it very simple to check whether an item is in a list. Simply use the in operator.

lst = ['test', 'twest', 'tweast', 'treast']

'test' in lst
# Out: True

'toast' in lst
# Out: False

Note: the in operator on sets is asymptotically faster than on lists. If you need to use it many times on potentially large lists, you may want to convert your list to a set, and test the presence of elements on the set.

slst = set(lst)
'test' in slst
# Out: True