How to slice a list of tuples in python?

Question

Assuming:

L = [(0,'a'), (1,'b'), (2,'c')]

How to get the index 0 of each tuple as the pretended result:

[0, 1, 2]

To get that I used python list comprehension and solved the problem:

[num[0] for num in L]

Still, it must be a pythonic way to slice it like L[:1], but of course this slincing dont work.

Is there better solution?

Answer 1

You can use * unpacking with zip().

>>> l = [(0,'a'), (1,'b'), (2,'c')]
>>> for item in zip(*l)[0]:
...     print item,
...
0 1 2

For Python 3, zip() doesn't produce a list automatically, so you would either have to send the zip object to list() or use next(iter()) or something:

>>> l = [(0,'a'), (1,'b'), (2,'c')]
>>> print(*next(iter(zip(*l))))
0 1 2

But yours is already perfectly fine.