Trying to swap positions in a list












2















Writing a simple code to print a random list, the swap the first position integer with the last position integer and re-print the list. Keep getting error saying not subscriptable. This is for a basic python class but we are on Thanksgiving break and can't talk to professor, due when we get back. 



import random



def main():



    mylist=



    for i in range(15):

        mylist.append(random.randrange(0,25))



    print(mylist)







    def swap():

        a, b = mylist.index[0], mylist.index[14]

        mylist[b], mylist[a] = mylist[a], mylist[b]

        print(mylist)



    swap()



main()





python python-3.7







share|improve this question




















  • 1





    a and b will be set to the first and last elements of the list, so trying to access mylist[a] and mylist[b] is wrong (a and b are not indices, they are the actual values). Try mylist[0], mylist[14] = a, b instead.

    – divesh premdeep
    Nov 21 '18 at 1:12


















2















Writing a simple code to print a random list, the swap the first position integer with the last position integer and re-print the list. Keep getting error saying not subscriptable. This is for a basic python class but we are on Thanksgiving break and can't talk to professor, due when we get back. 



import random



def main():



    mylist=



    for i in range(15):

        mylist.append(random.randrange(0,25))



    print(mylist)







    def swap():

        a, b = mylist.index[0], mylist.index[14]

        mylist[b], mylist[a] = mylist[a], mylist[b]

        print(mylist)



    swap()



main()





python python-3.7







share|improve this question




















  • 1





    a and b will be set to the first and last elements of the list, so trying to access mylist[a] and mylist[b] is wrong (a and b are not indices, they are the actual values). Try mylist[0], mylist[14] = a, b instead.

    – divesh premdeep
    Nov 21 '18 at 1:12
















2












2








2








Writing a simple code to print a random list, the swap the first position integer with the last position integer and re-print the list. Keep getting error saying not subscriptable. This is for a basic python class but we are on Thanksgiving break and can't talk to professor, due when we get back. 



import random



def main():



    mylist=



    for i in range(15):

        mylist.append(random.randrange(0,25))



    print(mylist)







    def swap():

        a, b = mylist.index[0], mylist.index[14]

        mylist[b], mylist[a] = mylist[a], mylist[b]

        print(mylist)



    swap()



main()





python python-3.7







share|improve this question
















Writing a simple code to print a random list, the swap the first position integer with the last position integer and re-print the list. Keep getting error saying not subscriptable. This is for a basic python class but we are on Thanksgiving break and can't talk to professor, due when we get back. 



import random



def main():



    mylist=



    for i in range(15):

        mylist.append(random.randrange(0,25))



    print(mylist)







    def swap():

        a, b = mylist.index[0], mylist.index[14]

        mylist[b], mylist[a] = mylist[a], mylist[b]

        print(mylist)



    swap()



main()





python python-3.7




python python-3.7






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Nov 21 '18 at 5:22









Julian Peller

8941511




8941511










asked Nov 21 '18 at 1:06









Collin Dee CortezCollin Dee Cortez

101




101








  • 1





    a and b will be set to the first and last elements of the list, so trying to access mylist[a] and mylist[b] is wrong (a and b are not indices, they are the actual values). Try mylist[0], mylist[14] = a, b instead.

    – divesh premdeep
    Nov 21 '18 at 1:12
















  • 1





    a and b will be set to the first and last elements of the list, so trying to access mylist[a] and mylist[b] is wrong (a and b are not indices, they are the actual values). Try mylist[0], mylist[14] = a, b instead.

    – divesh premdeep
    Nov 21 '18 at 1:12










1




1





a and b will be set to the first and last elements of the list, so trying to access mylist[a] and mylist[b] is wrong (a and b are not indices, they are the actual values). Try mylist[0], mylist[14] = a, b instead.

– divesh premdeep
Nov 21 '18 at 1:12







a and b will be set to the first and last elements of the list, so trying to access mylist[a] and mylist[b] is wrong (a and b are not indices, they are the actual values). Try mylist[0], mylist[14] = a, b instead.

– divesh premdeep
Nov 21 '18 at 1:12














2 Answers
2






active

oldest

votes


















3














You need to hold one of the values in a variable and then swap.



def swap():

    x = mylist[0]

    mylist[0] = mylist[14]

    mylist[14] = x



    print(mylist)





share|improve this answer































    1














    You are swapping with indexes equal to the values in the list (instead of indexes).



    Try:



    mylist[0], mylist[-1] = mylist[-1], mylist[0]



    On another observation, I believe you have to pass mylist to swap as a parameter. (unless swap is defined in main).






    share|improve this answer

























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      2 Answers
      2






      active

      oldest

      votes








      2 Answers
      2






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes









      3














      You need to hold one of the values in a variable and then swap.



      def swap():
      
    x = mylist[0]
      
    mylist[0] = mylist[14]
      
    mylist[14] = x
      

      
    print(mylist)





      share|improve this answer




























        3














        You need to hold one of the values in a variable and then swap.



        def swap():
        
    x = mylist[0]
        
    mylist[0] = mylist[14]
        
    mylist[14] = x
        

        
    print(mylist)





        share|improve this answer


























          3












          3








          3







          You need to hold one of the values in a variable and then swap.



          def swap():
          
    x = mylist[0]
          
    mylist[0] = mylist[14]
          
    mylist[14] = x
          

          
    print(mylist)





          share|improve this answer













          You need to hold one of the values in a variable and then swap.



          def swap():
          
    x = mylist[0]
          
    mylist[0] = mylist[14]
          
    mylist[14] = x
          

          
    print(mylist)






          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered Nov 21 '18 at 1:12









          Cory LCory L

          1599




          1599

























              1














              You are swapping with indexes equal to the values in the list (instead of indexes).



              Try:



              mylist[0], mylist[-1] = mylist[-1], mylist[0]



              On another observation, I believe you have to pass mylist to swap as a parameter. (unless swap is defined in main).






              share|improve this answer






























                1














                You are swapping with indexes equal to the values in the list (instead of indexes).



                Try:



                mylist[0], mylist[-1] = mylist[-1], mylist[0]



                On another observation, I believe you have to pass mylist to swap as a parameter. (unless swap is defined in main).






                share|improve this answer




























                  1












                  1








                  1







                  You are swapping with indexes equal to the values in the list (instead of indexes).



                  Try:



                  mylist[0], mylist[-1] = mylist[-1], mylist[0]



                  On another observation, I believe you have to pass mylist to swap as a parameter. (unless swap is defined in main).






                  share|improve this answer















                  You are swapping with indexes equal to the values in the list (instead of indexes).



                  Try:



                  mylist[0], mylist[-1] = mylist[-1], mylist[0]



                  On another observation, I believe you have to pass mylist to swap as a parameter. (unless swap is defined in main).







                  share|improve this answer














                  share|improve this answer



                  share|improve this answer








                  edited Nov 21 '18 at 1:26

























                  answered Nov 21 '18 at 1:13









                  Chris CharleyChris Charley

                  3,66021618




                  3,66021618






























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