How to Make my Merge output Horizontally instead of Vertically in python

Question

I have this python3 code that merges my sub-list to a single list:

l=[[4, 5, 6], [10], [1, 2, 3], [10], [1, 2, 3], [10], [4, 5, 6], [1, 2, 3], [4, 5, 6], [4, 5, 6], [7, 8, 9], [1, 2, 3], [7, 8, 9], [1, 2, 3], [4, 5, 6], [7, 8, 9], [4, 5, 6], [10], [7, 8, 9], [7, 8, 9]]

import itertools
merged = list(itertools.chain(*l))

from collections import Iterable

def flatten(items):
    """Yield items from any nested iterable; see Reference."""
    for x in items:
        if isinstance(x, Iterable) and not 
isinstance(x, (str, bytes)):
            for sub_x in flatten(x):
                yield sub_x
        else:
            yield x

merged = list(itertools.chain(*l))
merged

The Undesired Shape of the Output

Though the output produces what I want but the shape of the output is not what I want the output comes out in vertical shape as shown bellow:

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

The Desirable Shape of the Output as I Would Want It

I would rather want the output to come out horizontally as I present bellow:

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

Please help me out, I will not mind if there is a way to make this happen different from my code.

Answer 1

Instead just use list comprehention:

l=[[4, 5, 6], [10], [1, 2, 3], [10], [1, 2, 3], [10], [4, 5, 6], [1, 2, 3], [4, 5, 6], [4, 5, 6], [7, 8, 9], [1, 2, 3], [7, 8, 9], [1, 2, 3], [4, 5, 6], [7, 8, 9], [4, 5, 6], [10], [7, 8, 9], [7, 8, 9]]

new_l=[j for i in l for j in i]
print(new_l)

Output :

C:\Users\Desktop>py x.py
[4, 5, 6, 10, 1, 2, 3, 10, 1, 2, 3, 10, 4, 5, 6, 1, 2, 3, 4, 5, 6, 4, 5, 6, 7, 8, 9, 1, 2, 3, 7, 8, 9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 4, 5, 6, 10, 7, 8, 9, 7, 8, 9]