flatten list of lists of lists to a list of lists

Question

I\'ve already searched SO for how to flatten a list of lists (i.e. here:Making a flat list out of list of lists in Python) but none of the solutions I find addresses flatten

Answer 1

This is an inside-out version of fl00r's recursive answer which coincides more with what OP was after:

def flatten(lists,n):
    if n == 1:
        return [x for xs in lists for x in xs]   
    else:
        return [flatten(xs,n-1) for xs in lists]


>>> flatten(my_list,1)
[[1, 2, 3], [4, 5], [9], [8, 9, 10], [3, 4, 6], [1]]
>>> flatten(my_list,2)
[[1, 2, 3, 4, 5], [9, 8, 9, 10, 3, 4, 6], [1]]