How to loop over a python list using the index numbers?

Question

I was trying to loop over a list in python using the indices but it drops error. Can you guys help me out with this? What could be the syntax that could fix this ?

abs = [10,20,40] 

for i in abs: 
    new_abs = abs[i]+ abs[i+1]
    print(new_abs)

So, i have managed to use hard code for the temporary use.

abs = [10,20,40] 
new_abs = [ abs[0], abs[0]+ abs[1] , abs[1]+abs[2] ] 
print(new_abs)

Can you please, let me know the proper syntax to loop over this index numbers?

`i` should be the indices, you're currently looping on the values. Use `for i in range(len(abs)-1):` — Thierry Lathuille, Apr 26 '20 at 10:38
didn't get you. may be you would like to define what `new_abs` is ? `for i in range(len(abs)): print(abs[i])` syntax iterate through list with the help of indexes. and `for i in abs: print(i)` will directly print your elements in abs. — shivank98, Apr 26 '20 at 10:39
`print(abs[0])` followed by `for index, item in enumerate(abs[:-1]): print(item+abs[index+1])` would be the solution to your summation problem - `enumerate(abs[:-1])` to avoid IndexError for the last element - at least thats the logic of your second code parts — Patrick Artner, Apr 26 '20 at 10:45

score 0 · Answer 1 · answered Apr 26 '20 at 10:40

Looping over lists in python you have few options

for i in abs:
   print(i)

will print you all items in the lists. If you want to loop over lists items with indexes you can use

for index, item in enumerate(abs):
    print(index, item)

that will lop over each item and will provide you the index number of the item in the list and the current item.

How to loop over a python list using the index numbers?

1 Answers1