From 'list of lists of lists' to 'list of lists' - Python

Question

I have an issue I cannot go thorugh. I need list of lists instead of list of lists of lists? Is there any simple command that 'unlists' one level of such 'deep' list in Python? Here is what I have:

[[['this', 'is', 'the', 'good', 'machine', 'learning', 'book']],
[['this', 'is', 'another', 'book']]]

and where I need to get to:

[['this', 'is', 'the', 'good', 'machine', 'learning', 'book'],
['this', 'is',  'another', 'book']]

I was trying to resolve it with function below

from pandas.core.common import flatten
list(flatten(x))

...but it breaks everything into one list...

['this', 'is', 'the', 'good', 'machine', 'learning', 'book', 'this', 'is',  'another', 'book']

Pls help :)

score 2 · Accepted Answer · answered Apr 23 '20 at 08:02

2

You can simply apply it only to the sublists:

[list(flatten(y)) for y in x]

answered Apr 23 '20 at 08:02

user2390182

72,016
6
67
89

Wow, so easy... :) Thank you, it works! I'm switching from R to Python and some things suprise me in Python... – Kamil Filipek Apr 23 '20 at 08:32

score 1 · Answer 2 · answered Apr 23 '20 at 08:02

1

[item for sub_list in your_list for item in sub_list]

answered Apr 23 '20 at 08:02

Alexander Lekontsev

992
6
17

I stay with flatten from Pandas but this one also works. Thak you! – Kamil Filipek Apr 23 '20 at 08:33

From 'list of lists of lists' to 'list of lists' - Python

2 Answers2