Accessing multiple element of list using loop

Question

I have a lists

A = [[1, 2, 3], [4, 5, 6], [7, 8, 9], [10, 11, 12]]

I want to iterate to access 1, 4, 7, 10, then 2, 5, 8, 11, and then 3, 6, 9, 12. How to make this iteration?

kindly post how the output should look ... ```list(zip(*A))``` ? — sammywemmy, May 01 '20 at 00:38
try a combination of [zip](https://docs.python.org/3.3/library/functions.html#zip) and [chain(from itertools)](https://docs.python.org/3.8/library/itertools.html#itertools.chain.from_iterable) : ```list(chain.from_iterable(zip(*A)))``` — sammywemmy, May 01 '20 at 00:41

Tom Planche · Accepted Answer · 2020-05-01T18:14:04.650

1

You can access them using

for i in range(len(A[0])):
    for j in range(len(A)):
        print(A[j][i])

edited May 01 '20 at 18:14

answered May 01 '20 at 00:43

Tom Planche

116
11

for i in range(len(A[0])): for j in range(len(A)): print(A[j][i]) – Tom Planche May 01 '20 at 10:46
@MarianD didn't though about it sorry.. – Tom Planche May 01 '20 at 18:15

score 0 · Answer 2 · answered May 01 '20 at 00:52

If you can use something that’s not in the standard library, numpy is a good tool for modifying lists and matrices. You can do something like the following:

import numpy as np

A = [[1, 2, 3], [4, 5, 6], [7, 8, 9], [10, 11, 12]] 

print(np.asarray(A).T)

Accessing multiple element of list using loop

2 Answers2