Flatten tuples when nested in Python

Question

As an output from a function, I get tuples in either the form a and b as shown below:

a = ((x, y), z)
b = (x, y)

I would like to flatten the nested form to be as follows:

a = (x, y, z)

This will always result in me having a tuple which is one layer deep, regardless of what I get as a return from my function.

What is the quickest and most efficient way to do this in Python 3?

Potential duplicate of [this question](https://stackoverflow.com/a/2158532/5763413)? — blackbrandt, Jul 17 '19 at 15:08
Why not return (x, y, z) from the function or is it not yours? — Fredrik, Jul 17 '19 at 15:10

Eugene Yarmash · Answer 1 · 2019-07-17T15:20:58.343

1

You could try to unpack the tuple and catch any TypeError's:

def flatten(a):
    try:
        (x, y), z = a
        return x, y, z
    except TypeError:
        return a

print(flatten(((1, 2), 3)))  # (1, 2, 3)
print(flatten((1, 2)))  # (1, 2)

edited Jul 17 '19 at 15:20

answered Jul 17 '19 at 15:14

Eugene Yarmash

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score 1 · Answer 2 · answered Jul 17 '19 at 15:51

1

Use itertools.chain.from_iterable with tuple()

Ex:

from itertools import chain

a = (("x", "y"), "z")
b = ("x", "y")

for i in [a, b]:
    print(tuple(chain.from_iterable(i)))

Output:

('x', 'y', 'z')
('x', 'y')

answered Jul 17 '19 at 15:51

Rakesh

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Try this with tuples of integers, for example ;) – Eugene Yarmash Jul 17 '19 at 16:16
@EugeneYarmash Thanks. I just used OP's sample thinking it might be `string` – Rakesh Jul 17 '19 at 16:49

Flatten tuples when nested in Python

2 Answers2