Append tuple elements to a tuple of tuples in Python

Question

If I have a tuple, e.g. x = (1, 2, 3) and I want to append each of its elements to the front of each tuple of a tuple of tuples, e.g. y = (('a', 'b'), ('c', 'd'), ('e', 'f')) so that the final result is z = ((1, 'a', 'b'), (2, 'c', 'd'), (3, 'e', 'f')), what is the easiest way?

My first thought was zip(x,y), but that produces ((1, ('a', 'b')), (2, ('c', 'd')), (3, ('e', 'f'))).

timgeb · Accepted Answer · 2016-05-22 21:45:52Z

3

Use zip and flatten the result:

>>> x = (1, 2, 3)
>>> y = (('a', 'b'), ('c', 'd'), ('e', 'f'))
>>> tuple((a, b, c) for a, (b, c) in zip(x,y))
((1, 'a', 'b'), (2, 'c', 'd'), (3, 'e', 'f'))

Or, if you are using Python 3.5, do it in style:

>>> tuple((head, *tail) for head, tail in zip(x,y))
((1, 'a', 'b'), (2, 'c', 'd'), (3, 'e', 'f'))

answered May 22, 2016 at 21:45

timgeb

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Comments

Eli Korvigo · Accepted Answer · 2016-05-22 21:45:50Z

2

tuple((num, ) + other for num, other in zip(x, y))

Or

from itertools import chain

tuple(tuple(chain([num], other)) for num, other in zip(x, y))

answered May 22, 2016 at 21:45

Eli Korvigo

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2 Comments

Alex Hall Over a year ago

I don't see any benefit to the chain version.

Eli Korvigo Over a year ago

@AlexHall it's just another option for the record.

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