A one-liner to convert list of tuples to two lists?

Question

As above. Example:

a = [('P', 2), ('J, 3'), ('K', 3)]

Required: b = ['P', 'J', 'K'] and c = [2, 3, 3]

Check the first answer in the duplicate – Sheldore Jun 14 '19 at 19:58 — Sheldore, Jun 14 '19 at 19:58

score 3 · Accepted Answer · answered Jun 14 '19 at 19:56

3

Try this:

b, c = zip(*the_thing)

Example:

>>> b, c = zip(*[('P', 2), ('J', 3), ('K', 3)])
>>> b
('P', 'J', 'K')
>>> c
(2, 3, 3)

answered Jun 14 '19 at 19:56

ForceBru

Okay, that is genuis. Some explanation? Zip takes in lists or iterables in general, right? – Alex Deft Jun 14 '19 at 19:58
@AlexDeft, the thing is, it can take [_multiple_ iterables](https://docs.python.org/3/library/functions.html#zip). The asterisk (`*`) unpacks the list into multiple arguments, and then `zip` zips them. BTW, the answer to your question is in the last paragraph of the section about `zip` in the docs) – ForceBru Jun 14 '19 at 20:00
One last question, zip returns a zip object. Shouldn't we do this: list(zip(...)) and then unpack it? – Alex Deft Jun 14 '19 at 20:01
1

@AlexDeft, the zip object is iterable, so you can loop over it and use the `x, y, z = iterable` syntax. – ForceBru Jun 14 '19 at 20:02

1 Answers1