Appending two lists to one list in a specific way

Question

Let's say, I have two lists:

[a, b] and [c,d]

How can I get the following array as a result in Python?

[a, c]
[b, d]

no an array by concatenating two lists so I can get the result that is requested — Steven01123581321, Feb 12 '20 at 14:45
They are called lists, often confused with arrays. Expected output is `[ [a,c], [b, d] ]` right? — Ch3steR, Feb 12 '20 at 14:47
Does this answer your question? [Zip lists in Python](https://stackoverflow.com/questions/13704860/zip-lists-in-python) — vestland, Feb 12 '20 at 22:16

score 7 · Answer 1 · answered Feb 12 '20 at 14:44

7

Zip those lists.

list(map(list, zip(list1,list2)))

IDLE Output:

>>> list1 = [1,2]
>>> list2 = [10,11]
>>> list(map(list, zip(list1,list2)))
[[1, 10], [2, 11]]

answered Feb 12 '20 at 14:44

gsb22

user2653663 · Accepted Answer · 2020-02-12T14:52:36.650

6

Numpy solution:

import numpy as np

a = [1, 2]
b = [3, 4]
joint_array = np.asarray((a, b)).T

edited Feb 12 '20 at 14:52

answered Feb 12 '20 at 14:47

user2653663

score 3 · Answer 3 · answered Feb 12 '20 at 14:50

Since you specifically mentioned in the comments that you don't want a list of lists but rather a concatenation of the two lists:

[a,b]+[c,d]

the result will be [a,b,c,d]

otherwise if this is not what you wanted Gauri's or user2653663's answer might be what you want.

score 0 · Answer 4 · answered Feb 12 '20 at 15:42

0

If you mean to create two new list variables with the columnwise concatenations you can do this:

list1 = ["a", "b"]
list2 = ["c", "d"]

list3,list4 = [list(z) for z in zip(list1,list2)]
print(list3) 
print(list4) 

# ['a', 'c']
# ['b', 'd']

answered Feb 12 '20 at 15:42

Alain T.

4 Answers4