Python: next in for loop





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I want to use next to skip one or more items returned from a generator. Here is a simplified example designed to skip one item per loop (in actual use, I'd test n and depending on the result, may repeat the next() and the generator is from a package I don't control):



def gen():

for i in range(10):

    yield i



for g in gen():

   n = next(gen())

   print(g, n)


I expected the result to be



0 1

2 3


etc.



Instead I got



0 0

1 0


etc.



What am I doing wrong?






python generator next







share|improve this question





























    6















    I want to use next to skip one or more items returned from a generator. Here is a simplified example designed to skip one item per loop (in actual use, I'd test n and depending on the result, may repeat the next() and the generator is from a package I don't control):



    def gen():
    
for i in range(10):
    
    yield i
    

    
for g in gen():
    
   n = next(gen())
    
   print(g, n)


    I expected the result to be



    0 1
    
2 3


    etc.



    Instead I got



    0 0
    
1 0


    etc.



    What am I doing wrong?






    python generator next







    share|improve this question

























      6












      6








      6


      2






      I want to use next to skip one or more items returned from a generator. Here is a simplified example designed to skip one item per loop (in actual use, I'd test n and depending on the result, may repeat the next() and the generator is from a package I don't control):



      def gen():
      
for i in range(10):
      
    yield i
      

      
for g in gen():
      
   n = next(gen())
      
   print(g, n)


      I expected the result to be



      0 1
      
2 3


      etc.



      Instead I got



      0 0
      
1 0


      etc.



      What am I doing wrong?






      python generator next







      share|improve this question














      I want to use next to skip one or more items returned from a generator. Here is a simplified example designed to skip one item per loop (in actual use, I'd test n and depending on the result, may repeat the next() and the generator is from a package I don't control):



      def gen():
      
for i in range(10):
      
    yield i
      

      
for g in gen():
      
   n = next(gen())
      
   print(g, n)


      I expected the result to be



      0 1
      
2 3


      etc.



      Instead I got



      0 0
      
1 0


      etc.



      What am I doing wrong?






      python generator next




      python generator next






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked 7 hours ago









      foosionfoosion

      3,325144990




      3,325144990
























          1 Answer
          1






          active

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          7














          You're making a new generator each time you call gen(). Each new generator starts from 0.



          Instead, you can call it once and capture the return value.



          def gen():
          
    for i in range(10):
          
        yield i
          

          
x = gen()
          
for g in x:
          
    n = next(x)
          
    print(g, n)





          share|improve this answer
























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            1 Answer
            1






            active

            oldest

            votes








            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            7














            You're making a new generator each time you call gen(). Each new generator starts from 0.



            Instead, you can call it once and capture the return value.



            def gen():
            
    for i in range(10):
            
        yield i
            

            
x = gen()
            
for g in x:
            
    n = next(x)
            
    print(g, n)





            share|improve this answer




























              7














              You're making a new generator each time you call gen(). Each new generator starts from 0.



              Instead, you can call it once and capture the return value.



              def gen():
              
    for i in range(10):
              
        yield i
              

              
x = gen()
              
for g in x:
              
    n = next(x)
              
    print(g, n)





              share|improve this answer


























                7












                7








                7







                You're making a new generator each time you call gen(). Each new generator starts from 0.



                Instead, you can call it once and capture the return value.



                def gen():
                
    for i in range(10):
                
        yield i
                

                
x = gen()
                
for g in x:
                
    n = next(x)
                
    print(g, n)





                share|improve this answer













                You're making a new generator each time you call gen(). Each new generator starts from 0.



                Instead, you can call it once and capture the return value.



                def gen():
                
    for i in range(10):
                
        yield i
                

                
x = gen()
                
for g in x:
                
    n = next(x)
                
    print(g, n)






                share|improve this answer












                share|improve this answer



                share|improve this answer










                answered 7 hours ago









                khelwoodkhelwood

                32.2k74465




                32.2k74465
































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