You can just concatenate in a list comprehension, and use the len
of the desired elements to filter out as you do so
>>> [[i+j] for i, j, *_ in list_of_lists if len(i)==6 and len(j)==4]
[['9120000068'], ['9568118334'], ['9567183693'], ['9567230486']]
2
solved Join by specific length of character [closed]