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?










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?










    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?










      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






      share|improve this question













      share|improve this question











      share|improve this question




      share|improve this question










      asked 8 hours ago









      foosionfoosion

      3,325144990




      3,325144990
























          1 Answer
          1






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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









            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 8 hours ago









                khelwoodkhelwood

                32.2k74465




                32.2k74465
































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