Generate list of numbers and their negative counterparts in Python

Question

Is there a convenient one-liner to generate a list of numbers and their negative counterparts in Python?

For example, say I want to generate a list with the numbers 6 to 9 and -6 to -9.

My current approach is:

l = [x for x in range(6,10)] l += [-x for x in l] 

A simple "one-liner" would be:

l = [x for x in range(6,10)] + [y for y in range(-9, -5)] 

However, generating two lists and then joining them together seems inconvenient.

Answer 1

I am unsure if order matters, but you could create a tuple and unpack it in a list comprehension.

nums = [y for x in range(6,10) for y in (x,-x)] print(nums) [6, -6, 7, -7, 8, -8, 9, -9] 

Answer 2

Create a nice and readable function:

def range_with_negatives(start, end):     for x in range(start, end):         yield x         yield -x 

Usage:

list(range_with_negatives(6, 10)) 

That is how you get a convenient one-liner for anything. Avoid trying to look like a magic pro hacker.