Unpack List Of Lists Into List

I have list of lists of tuples: a = [[(1, 2), (3, 4), (5, 6)], [(7, 8), (9, 10)]] How can I make one list of tuples: b = [(1, 2), (3, 4), (5, 6), (7, 8), (9, 10)] Naive way is: b

Solution 1:

Using itertools

demo:

import itertools
a = [[(1, 2), (3, 4), (5, 6)], [(7, 8), (9, 10)]]
print(list(itertools.chain(*a)))

Output:

[(1, 2), (3, 4), (5, 6), (7, 8), (9, 10)]

Solution 2:

You don't want to append, you want to extend. You can use the really simple loop

a = [[(1, 2), (3, 4), (5, 6)], [(7, 8), (9, 10)]]
single_level_list = []
for lst in a:
    single_level_list.extend(lst)

print(single_level_list)

>>> [(1, 2), (3, 4), (5, 6), (7, 8), (9, 10)]

Solution 3:

This operation is called 'flatten' in some of other languages. In python, followings method might be shortest.

a = [[(1, 2), (3, 4), (5, 6)], [(7, 8), (9, 10)]]
sum(a, [])
// [(1, 2), (3, 4), (5, 6), (7, 8), (9, 10)]

It also work in the case the parent list have many child lists.

b = [[1],[2],[3],[4],[5]]
sum(b, [])
// [1, 2, 3, 4, 5]