How return one dimension list by list comprehension from nested list in list

Question

a = [
[1, 2],
[1, 2]
]

print([x for x in [x for x in a]])
[[1, 2], [1, 2]]

But I want to see something like that:

[1, 2, 1, 2]

How I cad do this?

is the depth of the nested list always the same? or can it be different? — Ren, Apr 19 '22 at 14:33

codester_09 · Accepted Answer · 2022-04-19T14:50:02.357

1

Try this.

a = [
[1, 2],
[1, 2]
]

lst = [q for i in a for q in i]
print(lst)

The above one is not always working it gives you an error if the list is something like this.

a = [[1, 2],[1, 2],2]

But this one always work.

a = [
[1, 2],
[1, 2]
]
lst = []
for i in a:
    if type(i) == list:
        lst.extend(i)
    else:
        lst.append(i)
print(lst)

edited Apr 19 '22 at 14:50

answered Apr 19 '22 at 14:34

codester_09

Yep, I just write extra square brackets... – Galoperidol Apr 19 '22 at 14:39
@Galoperidol Thanks if you don't mind you can vote too. – codester_09 Apr 19 '22 at 14:47
@Timus Sorry for that now working – codester_09 Apr 19 '22 at 14:50
1

Just as a reminder from [here](https://stackoverflow.com/help/how-to-answer): _"... avoid trying to answer questions which have already been asked and answered many times before."_ This question is easily identified as such. – Timus Apr 19 '22 at 17:27

score 0 · Answer 2 · answered Apr 19 '22 at 14:37

0

    a = [
[1, 2],
[1, 2]
]
flatten_list = lambda y:[x for a in y for x in flatten_list(a)] if type(y) is list else [y]

print(flatten_list(a))

answered Apr 19 '22 at 14:37

user12548239

2 Answers2