Checking if input has letters in it

Question

My error appears on this line:

if exclude3 not in Sent:

And it is:

TypeError: 'in <string>' requires string as left operand, not set

My code is:

import string

Word = input("Please give a word from the sentence")

exclude3 = set(string.ascii_letters)

if exclude3 not in Sent:
    print("")
elif exclude3 not in Word:
    print("")
else:

What is a left operand? What am I doing wrong and is there a simpler way to accomplish what I want? Should I be using something other than in and what should that be?

what do you hope to achieve with this code? your error is self explanatory but what you are trying to do is not — SirParselot, Feb 02 '16 at 13:33

Idos · Accepted Answer · 2016-02-02T13:50:21.373

1

exclude3 is not a string it is a set.
You try to use the in operator to check if a set is contained in another set which is wrong.

Maybe you meant to write: if Sent not in exclude3 ?

edited Feb 02 '16 at 13:50

answered Feb 02 '16 at 13:33

Idos

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score 0 · Answer 2 · answered Feb 02 '16 at 13:35

0

You need to check if the set and the string overlap. Either

if not exclude3.intersection(Sent):

or

if not any(x in Sent for x in exclude3):

will have the desired result.

The in operator works by testing if the left-hand argument is an element of the right-hand argument. The exception is str1 in str2, which tests if the left-hand str is a substring of the other.

answered Feb 02 '16 at 13:35

chepner

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Thanks everyone for the quick and good responses, it works now :) – Out North Feb 03 '16 at 14:04

score 0 · Answer 3 · answered Feb 02 '16 at 13:38

When you use in operand the left side and right side objects must be same type. And in this case exclude3 is a set object and you can not check its membership in a string.

Example:

>>> [] in ''
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'in <string>' requires string as left operand, not list

If you want to check the existence of all the items of a set in a string you can use set.intersection() as following :

if exclude3.interection(Sent) == exclude3:
      # do stuff

And for any intersection just check the validation of exclude3.interection(Sent):

if exclude3.interection(Sent):
     # do stuff

Checking if input has letters in it

3 Answers3