The zip function in Python 3

Question

I know how to use the zip   function in Python 3  My question is regarding the following which I somehow feel quite peculiar   I define two lists   lis1    0  1  2  3  lis2    4  5  6  7    and I use the zip   on these in the following ways   1  test1   zip  lis1  lis2   2  test2   list zip lis1  lis2     when I type test1 at the interpreter  I get this    zip object at 0x1007a06c8    So  I type list test1  at the interpreter and I get the intended result  but  when I type list test1  again  I get an empty list   What I find peculiar is that no matter how many times I type test2 at the interpreter I always get the intended result and never an empty list

User · Answer

The zip   function in Python 3 returns an iterator  That is the reason why when you print test1 you get -  lt zip object at 0x1007a06c8 gt   From documentation -     Make an iterator that aggregates elements from each of the iterables    But once you do - list test1  - you have exhausted the iterator  So after that anytime you do list test1  would only result in empty list   In case of test2  you have already created the list once  test2 is a list  and hence it will always be that list

User · Answer

Unlike in Python 2  the zip function in Python 3 returns an iterator   Iterators can only be exhausted  by something like making a list out of them  once   The purpose of this is to save memory by only generating the elements of the iterator as you need them  rather than putting it all into memory at once   If you want to reuse your zipped object  just create a list out of it as you do in your second example  and then duplicate the list by something like   test2   list zip lis1 lis2    zipped list   test2     zipped list 2   list test2

[python] The zip() function in Python 3

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