Convert list of list into single list

Question

Currently I have a list of lists

l=[['asd'],['fgd']].

I want to turn it into a list

goal_list=['asd','fgd']

but I do not know how to turn a list into the value inside it - does anyone have an idea how to this efficiently?

I tried iterating over the list, but was wondering if there might be some built-in function to it more efficiently :D. Thanks guys! — Ricefan, May 05 '19 at 07:43
Such action is called `list flattening`. It could be done in many ways - search for `python list flattening` and choose method that fit your needs best. — Daweo, May 05 '19 at 07:55

score 0 · Answer 1 · answered May 05 '19 at 07:51

This is a perfect use-case for itertools.chain, where we essentially chain all sublists together to flatten them!

from itertools import chain

def single_list(arr):
    return list(chain(*arr))

print(single_list([['asd'],['fgd']]))
print(single_list([['asd', 'abcd'],['fgd', 'def']]))

The output will be

['asd', 'fgd']
['asd', 'abcd', 'fgd', 'def']

score -1 · Answer 2 · answered May 05 '19 at 07:45

-1

Just use a list comprehension with two loops:

goal_list = [item for sublist in l for item in sublist]

answered May 05 '19 at 07:45

ruohola

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Convert list of list into single list

2 Answers2