convert nested list to int or str

Question

I have the following list structure:

the_given_list = [[[1],[2],[3]],[[1],[2],[3]]]

Indeed len(the_given_list) returns 2. I need to make the following list:

the_given_list = [[1,2,3],[1,2,3]]

How to do it?

Answer 1

[sum(x, []) for x in the_given_list]

---

Flatten the first-order element in the_given_list.

the_given_list = [sum(x, []) for x in the_given_list]
print(the_given_list)

Answer 2

To explain the above answer https://stackoverflow.com/a/57369395/1465553, this list

[[[1],[2],[3]],[[1],[2],[3]]]

can be seen as

[list1, list2]

and,

>> sum([[1],[2],[3]], [])
[1,2,3]
>>> sum([[1],[2],[3]], [5])
[5, 1, 2, 3]

Since the second argument to method sum defaults to 0, we need to explicitly pass empty list [] to it to overcome type mismatch (between int and list).

https://thepythonguru.com/python-builtin-functions/sum/

Answer 3

Use itertools.chain

In [15]: from itertools import chain                                                                                                                                                                        

In [16]: [list(chain(*i)) for i in the_given_list]                                                                                                                                                          
Out[16]: [[1, 2, 3], [1, 2, 3]]

Answer 4

the_given_list  = [ [ s[0] for s in f ] for f in the_given_list ]

Answer 5

Another solution:

the_given_list = [[[1],[2],[3]],[[1],[2],[3]]]
print([[j for sub in i for j in sub] for i in the_given_list])

Gives me:

[[1, 2, 3], [1, 2, 3]]

Check the original answer on list flattening:

https://stackoverflow.com/a/952952/5501407