Multiple 'In' operator in python












-4














arr = [1, True, 'a', 2]
print('a' in arr in arr) # False


Can you explain me why this code will output 'False'?



The question is closed.



Answer from @KlausD.: Actually it is a comparison operator chaining and will be interpreted as ('a' in arr) and (arr in arr).










share|improve this question
























  • Just do 'a' in arr
    – W-B
    Nov 11 at 7:05










  • I believe you're expecting True because, you see 'a' in arr in arr as True in arr ?
    – Austin
    Nov 11 at 7:08










  • @Austin, just run this code. It output False.
    – Matvey
    Nov 11 at 7:23










  • Please explain waht your expected result was, and why. The question as it is, is unclear
    – CIsForCookies
    Nov 11 at 7:27










  • @CIsForCookies, What did you not understand? I wanna understand why the expression " 'a' in arr in arr " is False
    – Matvey
    Nov 11 at 7:32


















-4














arr = [1, True, 'a', 2]
print('a' in arr in arr) # False


Can you explain me why this code will output 'False'?



The question is closed.



Answer from @KlausD.: Actually it is a comparison operator chaining and will be interpreted as ('a' in arr) and (arr in arr).










share|improve this question
























  • Just do 'a' in arr
    – W-B
    Nov 11 at 7:05










  • I believe you're expecting True because, you see 'a' in arr in arr as True in arr ?
    – Austin
    Nov 11 at 7:08










  • @Austin, just run this code. It output False.
    – Matvey
    Nov 11 at 7:23










  • Please explain waht your expected result was, and why. The question as it is, is unclear
    – CIsForCookies
    Nov 11 at 7:27










  • @CIsForCookies, What did you not understand? I wanna understand why the expression " 'a' in arr in arr " is False
    – Matvey
    Nov 11 at 7:32
















-4












-4








-4


0





arr = [1, True, 'a', 2]
print('a' in arr in arr) # False


Can you explain me why this code will output 'False'?



The question is closed.



Answer from @KlausD.: Actually it is a comparison operator chaining and will be interpreted as ('a' in arr) and (arr in arr).










share|improve this question















arr = [1, True, 'a', 2]
print('a' in arr in arr) # False


Can you explain me why this code will output 'False'?



The question is closed.



Answer from @KlausD.: Actually it is a comparison operator chaining and will be interpreted as ('a' in arr) and (arr in arr).







python python-3.x operators in-operator






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Nov 11 at 8:26

























asked Nov 11 at 7:04









Matvey

13




13












  • Just do 'a' in arr
    – W-B
    Nov 11 at 7:05










  • I believe you're expecting True because, you see 'a' in arr in arr as True in arr ?
    – Austin
    Nov 11 at 7:08










  • @Austin, just run this code. It output False.
    – Matvey
    Nov 11 at 7:23










  • Please explain waht your expected result was, and why. The question as it is, is unclear
    – CIsForCookies
    Nov 11 at 7:27










  • @CIsForCookies, What did you not understand? I wanna understand why the expression " 'a' in arr in arr " is False
    – Matvey
    Nov 11 at 7:32




















  • Just do 'a' in arr
    – W-B
    Nov 11 at 7:05










  • I believe you're expecting True because, you see 'a' in arr in arr as True in arr ?
    – Austin
    Nov 11 at 7:08










  • @Austin, just run this code. It output False.
    – Matvey
    Nov 11 at 7:23










  • Please explain waht your expected result was, and why. The question as it is, is unclear
    – CIsForCookies
    Nov 11 at 7:27










  • @CIsForCookies, What did you not understand? I wanna understand why the expression " 'a' in arr in arr " is False
    – Matvey
    Nov 11 at 7:32


















Just do 'a' in arr
– W-B
Nov 11 at 7:05




Just do 'a' in arr
– W-B
Nov 11 at 7:05












I believe you're expecting True because, you see 'a' in arr in arr as True in arr ?
– Austin
Nov 11 at 7:08




I believe you're expecting True because, you see 'a' in arr in arr as True in arr ?
– Austin
Nov 11 at 7:08












@Austin, just run this code. It output False.
– Matvey
Nov 11 at 7:23




@Austin, just run this code. It output False.
– Matvey
Nov 11 at 7:23












Please explain waht your expected result was, and why. The question as it is, is unclear
– CIsForCookies
Nov 11 at 7:27




Please explain waht your expected result was, and why. The question as it is, is unclear
– CIsForCookies
Nov 11 at 7:27












@CIsForCookies, What did you not understand? I wanna understand why the expression " 'a' in arr in arr " is False
– Matvey
Nov 11 at 7:32






@CIsForCookies, What did you not understand? I wanna understand why the expression " 'a' in arr in arr " is False
– Matvey
Nov 11 at 7:32














3 Answers
3






active

oldest

votes


















0














I believe this is what you are trying to do:



arr = [1, True, 'a', 2]
print( 'a' in arr)


Output:



True


Or this:



arr = [1, True, 'a', 2]
print(bool(['a' in arr]) in arr)


Output:



True





share|improve this answer





















  • you can just do print(('a' in arr) in arr) instead of print(bool(['a' in arr]) in arr) but that does not check if 'a' is in arr. It check if True is! Change arr to arr = ['a', 2] and verify
    – CIsForCookies
    Nov 11 at 7:21










  • Question is not clear. I am assuming he wants to get the output from 'a' in arr as True and then check if True in arr.
    – Sanchit Kumar
    Nov 11 at 7:22












  • Legit. I thought OP only wants to check if 'a' in arr. Either way, what actually being checked is if arr in arr, and then if 'a' is in the result :-P
    – CIsForCookies
    Nov 11 at 7:26










  • bool(['a' in arr]) is almost certainly not any part of what the questioner wanted, considering it's calling bool on a one-element list, and it'll return True no matter whether or not 'a' is in arr.
    – user2357112
    Nov 11 at 8:02



















0
















  1. print('a' in arr in arr) // False is interpeted as print('a' in arr in arr) // 0 which throws ZeroDivisionError: integer division or modulo by zero error. If you meant to comment out the False, do it using "#", not "//" (e.g. print('a' in arr in arr) # False)


  2. 'a' in arr in arr is read from right to left[1]: check if arr in arr (False), and then check if 'a' in False (False)


  3. Using @Klaus D's helpful comment - print('a' in arr in arr) is evaluated as print(('a' in arr) and (arr in arr)) due to operator chaining. This, in turn is processed into print(True and False) -> print(False)


To check if 'a' is in arr, just check print('a' in arr) # prints True



[1] Well, not exactly. As can seen from [ In which order is an if statement evaluated in Python ], the evaluation is right to left ,so this is what actually happens: (1) check if 'a' is in "something". (2) evaluate this "something" by checking if arr in arr. (3) use the reault of said something (which is False as sadly, arr isn't a member of itslef) and check if 'a' is inside that (meaning, check if 'a' in True, which again, is False[1]






share|improve this answer























  • 1. Yeah, i'm sorry. There must be a "#"
    – Matvey
    Nov 11 at 7:35










  • 2. 'a' in False is incorrect expression. It will throws error.
    – Matvey
    Nov 11 at 7:36






  • 2




    1. Actually it is a comparison operator chaining and will be interpreted as ('a' in arr) and (arr in arr).
    – Klaus D.
    Nov 11 at 7:48










  • @KlausD, You're right. Thanks, man. It's correct answer for my question.
    – Matvey
    Nov 11 at 7:52





















0














It is False because 'a' is in 'arr' but 'arr' is not in 'arr'.



Meaning 'arr' can't be in itself.






share|improve this answer





















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    3 Answers
    3






    active

    oldest

    votes








    3 Answers
    3






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    0














    I believe this is what you are trying to do:



    arr = [1, True, 'a', 2]
    print( 'a' in arr)


    Output:



    True


    Or this:



    arr = [1, True, 'a', 2]
    print(bool(['a' in arr]) in arr)


    Output:



    True





    share|improve this answer





















    • you can just do print(('a' in arr) in arr) instead of print(bool(['a' in arr]) in arr) but that does not check if 'a' is in arr. It check if True is! Change arr to arr = ['a', 2] and verify
      – CIsForCookies
      Nov 11 at 7:21










    • Question is not clear. I am assuming he wants to get the output from 'a' in arr as True and then check if True in arr.
      – Sanchit Kumar
      Nov 11 at 7:22












    • Legit. I thought OP only wants to check if 'a' in arr. Either way, what actually being checked is if arr in arr, and then if 'a' is in the result :-P
      – CIsForCookies
      Nov 11 at 7:26










    • bool(['a' in arr]) is almost certainly not any part of what the questioner wanted, considering it's calling bool on a one-element list, and it'll return True no matter whether or not 'a' is in arr.
      – user2357112
      Nov 11 at 8:02
















    0














    I believe this is what you are trying to do:



    arr = [1, True, 'a', 2]
    print( 'a' in arr)


    Output:



    True


    Or this:



    arr = [1, True, 'a', 2]
    print(bool(['a' in arr]) in arr)


    Output:



    True





    share|improve this answer





















    • you can just do print(('a' in arr) in arr) instead of print(bool(['a' in arr]) in arr) but that does not check if 'a' is in arr. It check if True is! Change arr to arr = ['a', 2] and verify
      – CIsForCookies
      Nov 11 at 7:21










    • Question is not clear. I am assuming he wants to get the output from 'a' in arr as True and then check if True in arr.
      – Sanchit Kumar
      Nov 11 at 7:22












    • Legit. I thought OP only wants to check if 'a' in arr. Either way, what actually being checked is if arr in arr, and then if 'a' is in the result :-P
      – CIsForCookies
      Nov 11 at 7:26










    • bool(['a' in arr]) is almost certainly not any part of what the questioner wanted, considering it's calling bool on a one-element list, and it'll return True no matter whether or not 'a' is in arr.
      – user2357112
      Nov 11 at 8:02














    0












    0








    0






    I believe this is what you are trying to do:



    arr = [1, True, 'a', 2]
    print( 'a' in arr)


    Output:



    True


    Or this:



    arr = [1, True, 'a', 2]
    print(bool(['a' in arr]) in arr)


    Output:



    True





    share|improve this answer












    I believe this is what you are trying to do:



    arr = [1, True, 'a', 2]
    print( 'a' in arr)


    Output:



    True


    Or this:



    arr = [1, True, 'a', 2]
    print(bool(['a' in arr]) in arr)


    Output:



    True






    share|improve this answer












    share|improve this answer



    share|improve this answer










    answered Nov 11 at 7:06









    Sanchit Kumar

    31117




    31117












    • you can just do print(('a' in arr) in arr) instead of print(bool(['a' in arr]) in arr) but that does not check if 'a' is in arr. It check if True is! Change arr to arr = ['a', 2] and verify
      – CIsForCookies
      Nov 11 at 7:21










    • Question is not clear. I am assuming he wants to get the output from 'a' in arr as True and then check if True in arr.
      – Sanchit Kumar
      Nov 11 at 7:22












    • Legit. I thought OP only wants to check if 'a' in arr. Either way, what actually being checked is if arr in arr, and then if 'a' is in the result :-P
      – CIsForCookies
      Nov 11 at 7:26










    • bool(['a' in arr]) is almost certainly not any part of what the questioner wanted, considering it's calling bool on a one-element list, and it'll return True no matter whether or not 'a' is in arr.
      – user2357112
      Nov 11 at 8:02


















    • you can just do print(('a' in arr) in arr) instead of print(bool(['a' in arr]) in arr) but that does not check if 'a' is in arr. It check if True is! Change arr to arr = ['a', 2] and verify
      – CIsForCookies
      Nov 11 at 7:21










    • Question is not clear. I am assuming he wants to get the output from 'a' in arr as True and then check if True in arr.
      – Sanchit Kumar
      Nov 11 at 7:22












    • Legit. I thought OP only wants to check if 'a' in arr. Either way, what actually being checked is if arr in arr, and then if 'a' is in the result :-P
      – CIsForCookies
      Nov 11 at 7:26










    • bool(['a' in arr]) is almost certainly not any part of what the questioner wanted, considering it's calling bool on a one-element list, and it'll return True no matter whether or not 'a' is in arr.
      – user2357112
      Nov 11 at 8:02
















    you can just do print(('a' in arr) in arr) instead of print(bool(['a' in arr]) in arr) but that does not check if 'a' is in arr. It check if True is! Change arr to arr = ['a', 2] and verify
    – CIsForCookies
    Nov 11 at 7:21




    you can just do print(('a' in arr) in arr) instead of print(bool(['a' in arr]) in arr) but that does not check if 'a' is in arr. It check if True is! Change arr to arr = ['a', 2] and verify
    – CIsForCookies
    Nov 11 at 7:21












    Question is not clear. I am assuming he wants to get the output from 'a' in arr as True and then check if True in arr.
    – Sanchit Kumar
    Nov 11 at 7:22






    Question is not clear. I am assuming he wants to get the output from 'a' in arr as True and then check if True in arr.
    – Sanchit Kumar
    Nov 11 at 7:22














    Legit. I thought OP only wants to check if 'a' in arr. Either way, what actually being checked is if arr in arr, and then if 'a' is in the result :-P
    – CIsForCookies
    Nov 11 at 7:26




    Legit. I thought OP only wants to check if 'a' in arr. Either way, what actually being checked is if arr in arr, and then if 'a' is in the result :-P
    – CIsForCookies
    Nov 11 at 7:26












    bool(['a' in arr]) is almost certainly not any part of what the questioner wanted, considering it's calling bool on a one-element list, and it'll return True no matter whether or not 'a' is in arr.
    – user2357112
    Nov 11 at 8:02




    bool(['a' in arr]) is almost certainly not any part of what the questioner wanted, considering it's calling bool on a one-element list, and it'll return True no matter whether or not 'a' is in arr.
    – user2357112
    Nov 11 at 8:02













    0
















    1. print('a' in arr in arr) // False is interpeted as print('a' in arr in arr) // 0 which throws ZeroDivisionError: integer division or modulo by zero error. If you meant to comment out the False, do it using "#", not "//" (e.g. print('a' in arr in arr) # False)


    2. 'a' in arr in arr is read from right to left[1]: check if arr in arr (False), and then check if 'a' in False (False)


    3. Using @Klaus D's helpful comment - print('a' in arr in arr) is evaluated as print(('a' in arr) and (arr in arr)) due to operator chaining. This, in turn is processed into print(True and False) -> print(False)


    To check if 'a' is in arr, just check print('a' in arr) # prints True



    [1] Well, not exactly. As can seen from [ In which order is an if statement evaluated in Python ], the evaluation is right to left ,so this is what actually happens: (1) check if 'a' is in "something". (2) evaluate this "something" by checking if arr in arr. (3) use the reault of said something (which is False as sadly, arr isn't a member of itslef) and check if 'a' is inside that (meaning, check if 'a' in True, which again, is False[1]






    share|improve this answer























    • 1. Yeah, i'm sorry. There must be a "#"
      – Matvey
      Nov 11 at 7:35










    • 2. 'a' in False is incorrect expression. It will throws error.
      – Matvey
      Nov 11 at 7:36






    • 2




      1. Actually it is a comparison operator chaining and will be interpreted as ('a' in arr) and (arr in arr).
      – Klaus D.
      Nov 11 at 7:48










    • @KlausD, You're right. Thanks, man. It's correct answer for my question.
      – Matvey
      Nov 11 at 7:52


















    0
















    1. print('a' in arr in arr) // False is interpeted as print('a' in arr in arr) // 0 which throws ZeroDivisionError: integer division or modulo by zero error. If you meant to comment out the False, do it using "#", not "//" (e.g. print('a' in arr in arr) # False)


    2. 'a' in arr in arr is read from right to left[1]: check if arr in arr (False), and then check if 'a' in False (False)


    3. Using @Klaus D's helpful comment - print('a' in arr in arr) is evaluated as print(('a' in arr) and (arr in arr)) due to operator chaining. This, in turn is processed into print(True and False) -> print(False)


    To check if 'a' is in arr, just check print('a' in arr) # prints True



    [1] Well, not exactly. As can seen from [ In which order is an if statement evaluated in Python ], the evaluation is right to left ,so this is what actually happens: (1) check if 'a' is in "something". (2) evaluate this "something" by checking if arr in arr. (3) use the reault of said something (which is False as sadly, arr isn't a member of itslef) and check if 'a' is inside that (meaning, check if 'a' in True, which again, is False[1]






    share|improve this answer























    • 1. Yeah, i'm sorry. There must be a "#"
      – Matvey
      Nov 11 at 7:35










    • 2. 'a' in False is incorrect expression. It will throws error.
      – Matvey
      Nov 11 at 7:36






    • 2




      1. Actually it is a comparison operator chaining and will be interpreted as ('a' in arr) and (arr in arr).
      – Klaus D.
      Nov 11 at 7:48










    • @KlausD, You're right. Thanks, man. It's correct answer for my question.
      – Matvey
      Nov 11 at 7:52
















    0












    0








    0








    1. print('a' in arr in arr) // False is interpeted as print('a' in arr in arr) // 0 which throws ZeroDivisionError: integer division or modulo by zero error. If you meant to comment out the False, do it using "#", not "//" (e.g. print('a' in arr in arr) # False)


    2. 'a' in arr in arr is read from right to left[1]: check if arr in arr (False), and then check if 'a' in False (False)


    3. Using @Klaus D's helpful comment - print('a' in arr in arr) is evaluated as print(('a' in arr) and (arr in arr)) due to operator chaining. This, in turn is processed into print(True and False) -> print(False)


    To check if 'a' is in arr, just check print('a' in arr) # prints True



    [1] Well, not exactly. As can seen from [ In which order is an if statement evaluated in Python ], the evaluation is right to left ,so this is what actually happens: (1) check if 'a' is in "something". (2) evaluate this "something" by checking if arr in arr. (3) use the reault of said something (which is False as sadly, arr isn't a member of itslef) and check if 'a' is inside that (meaning, check if 'a' in True, which again, is False[1]






    share|improve this answer
















    1. print('a' in arr in arr) // False is interpeted as print('a' in arr in arr) // 0 which throws ZeroDivisionError: integer division or modulo by zero error. If you meant to comment out the False, do it using "#", not "//" (e.g. print('a' in arr in arr) # False)


    2. 'a' in arr in arr is read from right to left[1]: check if arr in arr (False), and then check if 'a' in False (False)


    3. Using @Klaus D's helpful comment - print('a' in arr in arr) is evaluated as print(('a' in arr) and (arr in arr)) due to operator chaining. This, in turn is processed into print(True and False) -> print(False)


    To check if 'a' is in arr, just check print('a' in arr) # prints True



    [1] Well, not exactly. As can seen from [ In which order is an if statement evaluated in Python ], the evaluation is right to left ,so this is what actually happens: (1) check if 'a' is in "something". (2) evaluate this "something" by checking if arr in arr. (3) use the reault of said something (which is False as sadly, arr isn't a member of itslef) and check if 'a' is inside that (meaning, check if 'a' in True, which again, is False[1]







    share|improve this answer














    share|improve this answer



    share|improve this answer








    edited Nov 11 at 8:13

























    answered Nov 11 at 7:11









    CIsForCookies

    6,68311546




    6,68311546












    • 1. Yeah, i'm sorry. There must be a "#"
      – Matvey
      Nov 11 at 7:35










    • 2. 'a' in False is incorrect expression. It will throws error.
      – Matvey
      Nov 11 at 7:36






    • 2




      1. Actually it is a comparison operator chaining and will be interpreted as ('a' in arr) and (arr in arr).
      – Klaus D.
      Nov 11 at 7:48










    • @KlausD, You're right. Thanks, man. It's correct answer for my question.
      – Matvey
      Nov 11 at 7:52




















    • 1. Yeah, i'm sorry. There must be a "#"
      – Matvey
      Nov 11 at 7:35










    • 2. 'a' in False is incorrect expression. It will throws error.
      – Matvey
      Nov 11 at 7:36






    • 2




      1. Actually it is a comparison operator chaining and will be interpreted as ('a' in arr) and (arr in arr).
      – Klaus D.
      Nov 11 at 7:48










    • @KlausD, You're right. Thanks, man. It's correct answer for my question.
      – Matvey
      Nov 11 at 7:52


















    1. Yeah, i'm sorry. There must be a "#"
    – Matvey
    Nov 11 at 7:35




    1. Yeah, i'm sorry. There must be a "#"
    – Matvey
    Nov 11 at 7:35












    2. 'a' in False is incorrect expression. It will throws error.
    – Matvey
    Nov 11 at 7:36




    2. 'a' in False is incorrect expression. It will throws error.
    – Matvey
    Nov 11 at 7:36




    2




    2




    1. Actually it is a comparison operator chaining and will be interpreted as ('a' in arr) and (arr in arr).
    – Klaus D.
    Nov 11 at 7:48




    1. Actually it is a comparison operator chaining and will be interpreted as ('a' in arr) and (arr in arr).
    – Klaus D.
    Nov 11 at 7:48












    @KlausD, You're right. Thanks, man. It's correct answer for my question.
    – Matvey
    Nov 11 at 7:52






    @KlausD, You're right. Thanks, man. It's correct answer for my question.
    – Matvey
    Nov 11 at 7:52













    0














    It is False because 'a' is in 'arr' but 'arr' is not in 'arr'.



    Meaning 'arr' can't be in itself.






    share|improve this answer


























      0














      It is False because 'a' is in 'arr' but 'arr' is not in 'arr'.



      Meaning 'arr' can't be in itself.






      share|improve this answer
























        0












        0








        0






        It is False because 'a' is in 'arr' but 'arr' is not in 'arr'.



        Meaning 'arr' can't be in itself.






        share|improve this answer












        It is False because 'a' is in 'arr' but 'arr' is not in 'arr'.



        Meaning 'arr' can't be in itself.







        share|improve this answer












        share|improve this answer



        share|improve this answer










        answered Nov 11 at 9:40









        Jack Herer

        313112




        313112






























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