What is the role of the asterisk before the parameter?

Question

import numpy as np    
a = np.arange(6).reshape(2,3)
np.meshgrid(*[np.arange(x) for x in a.shape])

why does it works? what dose it mean adding an asterisk before list comprehension as a parameter?

Please update your question with an actual snippet of code, not an external image. — Soviut, Dec 07 '16 at 05:05
@Soviut - I don't think it matters much. It's a common duplicate anyway. — TigerhawkT3, Dec 07 '16 at 05:06
@TigerhawkT3 This is the first time I have asked questions in stackoverfolw, sorry for asking a duplicate question — DamonD, Dec 07 '16 at 05:38
Don't worry about it. Just, maybe Google a bit more next time. :) — TigerhawkT3, Dec 07 '16 at 05:38

Soviut · Accepted Answer · 2016-12-07T05:34:38.210

0

In python, an * unrolls a list.

That way you can use a list as a set of arguments.

some_args = ['first', False, 3]

do_something(*some_args)

In your case, the following is unrolling a list comprehension.

*[np.arange(x) for x in a.shape]

edited Dec 07 '16 at 05:34

answered Dec 07 '16 at 05:03

Soviut

This doesn't even answer the question, which was about function calls, not function definitions. – TigerhawkT3 Dec 07 '16 at 05:07
I think I get your point! Thank you – DamonD Dec 07 '16 at 05:17
@TigerhawkT3 You're right, I've updated my answer. – Soviut Dec 07 '16 at 05:35

1 Answers1