how to break elements in a python list

Question

I have an element in follow list as:

  [0.29839835, [734, 805, 679, 758], 'A']

I need to change it to

  [0.29839835, 734, 805, 679, 758, 'A']

Just break the inner set of elements [734, 805, 679, 758] from one elements to 4 elements. Any leads pls?

@Chris_Rands, is there a better dupe target? While the target has 49 answers, not one of them has the `itertools` solution, and indeed it's probably because the question there is more generalized. In which case, my answer below wouldn't fit on that question. — jpp, Nov 02 '18 at 09:19
@jpp 3 solutions on the first page use `itertools` in the dupe target, if you have a better one, then please do add it of course — Chris_Rands, Nov 02 '18 at 09:24
@Chris_Rands, You misunderstand my point. Adding my solution for **this specific use case** makes no point on the more general question. Because it doesn't answer the question.. While here it does. Don't get me wrong, I'll keep my answer as a community wiki. I just fail to see how someone can look at the answers there and come up with the solution I have below. *Or* how I can add my answer there. — jpp, Nov 02 '18 at 09:29
@sayan_sen, I've rolled it back. You shouldn't change your question materially once you've had an answer / answers. Please [ask a new question](https://stackoverflow.com/questions/ask). — jpp, Nov 02 '18 at 09:36

jpp · Answer 1 · 2018-11-02T09:37:12.990

1

For your specific data structure, you can use itertools.chain with a ternary condition:

from itertools import chain

x = [0.29839835, [734, 805, 679, 758], 'A']

res = list(chain.from_iterable([i] if not isinstance(i, list) else i for i in x))

[0.29839835, 734, 805, 679, 758, 'A']

For a generalised solution, see Flatten an irregular list of lists.

edited Nov 02 '18 at 09:37

answered Nov 02 '18 at 09:16

jpp

159,742
34
281
339

score 0 · Answer 2 · answered Nov 02 '18 at 10:39

This has already been answered here:

l = [0.29839835, [734, 805, 679, 758], 'A']
a = list()
def flatten(l, a):
    for i in l:
        if isinstance(i, list):
            flatten(i, a)
        else:
            a.append(i)
    return a
print(flatten(l, a))
#[0.29839835, 734, 805, 679, 758, 'A']

how to break elements in a python list

2 Answers2