python previous element in list loop

Question

please help with the issue. I need to compare an element of a loop with a previous element in python 3. The code below gives the error:

TypeError: 'int' object is not subscriptable

for index, (i, j) in enumerate(zip(a_list, b_list)):
    if j[index] == j[index-1]:
        a = 0

j is element which can be int. So it's not subscriptable. You might use list variable in place of j (btw, your requirement is not known/clear). — Austin
– Austin, Commented Apr 15, 2019 at 5:19
The following error means that you are getting an integer value in j. Check what is the value of j you are getting, It probably is an integer value. — Sumit S Chawla
– Sumit S Chawla, Commented Apr 15, 2019 at 5:20
I think you meant to do if a_list[index] == a_list[index-1]: or something. But that's obviously not going to work for the first element, since a_list[0 - 1] is going to look at the last element of a_list — user3064538
– user3064538, Commented Apr 15, 2019 at 5:21
Possible duplicate of How to get list index and element simultaneously in Python? — Allan
– Allan, Commented Apr 15, 2019 at 5:33

gmds · Accepted Answer · 2019-04-15 05:21:31Z

4

i and j are elements of a_list and b_list, and therefore they are not lists which you can access with [], but rather, simple ints (presumably).

Why not do this?

data = [1, 2, 2, 3, 4, 5, 5, 5, 3, 2, 7]

for first, second in zip(data, data[1:]):
    if first == second:
        print('Got a match!')

Output:

Got a match!
Got a match!
Got a match!

answered Apr 15, 2019 at 5:21

gmds

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