Flattening a list of tuples

Question

How can I loop through all the elements in a list of tuples, into an empty list?

For example:

tup_Before = [(69592, 69582), (69582, 69518), (69518, 69532), (69532, 69525)]

tup_After = [69592, 69582, 69582, 69518, 69518, 69532, 69532, 69525]

a trivial reduce : `list(reduce(lambda x, y: x + y, tup_Before))` (the lambda can be replaced by `operator.__add__` for readability) — njzk2, Mar 25 '14 at 18:49

score 1 · Accepted Answer · answered Mar 25 '14 at 18:43

A list comprehension:

tup_after = [v for t in tup_Before for v in t]

or use itertools.chain.from_iterable():

from itertools import chain
tup_after = list(chain.from_iterable(tup_Before))

Demo:

>>> tup_Before = [(69592, 69582), (69582, 69518), (69518, 69532), (69532, 69525)]
>>> [v for t in tup_Before for v in t]
[69592, 69582, 69582, 69518, 69518, 69532, 69532, 69525]
>>> from itertools import chain
>>> list(chain.from_iterable(tup_Before))
[69592, 69582, 69582, 69518, 69518, 69532, 69532, 69525]

score 0 · Answer 2 · answered Mar 25 '14 at 18:44

0

also, the least clear answer:

[l for l in l for l in l]

where l is your list name

answered Mar 25 '14 at 18:44

acushner

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score 0 · Answer 3 · answered Mar 25 '14 at 18:45

0

You can try using itertools.chain() and unpacking with *:

import itertools

new_tup = list(itertools.chain(*tup_before))

Demo:

>>> print new_tup
[69592, 69582, 69582, 69518, 69518, 69532, 69532, 69525]

answered Mar 25 '14 at 18:45

Christian Tapia

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Flattening a list of tuples

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