Loop and List in Python

Question

With below code, I was expecting to swap two lists and was expecting all the elements from 'names' list to 'Excluded_list'using Pop() function. But it is not working expectedly, can someone please tell the issue with below code ??

names=['Ram','Sham','Mohan','John','Kuldeep']
Excluded_list=[]
print('names list',names)
print('Excluded list ',Excluded_list)

Code to swap/reprint lists

for name in names:
    Excluded_list.append(names.pop())
print('names list',names)
print('Excluded list ',Excluded_list)

score 1 · Accepted Answer · answered Dec 08 '20 at 14:26

1

You are modifying "names" in the for-loop, which means that the "for name in names" does not evaluate as you expect.

Replace the for-loop with a while-loop.

while len(names):
    Excluded_list.append(names.pop())

answered Dec 08 '20 at 14:26

Kim Nyholm

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Thanks Kim, It really helped. But I am still confused over For loop failure, If possible can you please explain why it fails?? – sukhvinder singh Dec 08 '20 at 16:35
1

You should not modify the list (here names) you are iterating over. This is explained in this [answer](https://stackoverflow.com/a/6260097/8450075) – Kim Nyholm Dec 09 '20 at 10:37
Got it now .Thanks a lot !! – sukhvinder singh Dec 09 '20 at 15:54

Loop and List in Python

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