why do we use list comprehension in python code example

Example 1: python list comprehension

nums = [4, -7, 9, 1, -1, 8, -6]
half_of_nums = [x/2 for x in nums] #[2, -3.5, 4.5, 0.5, -0.5, 4, -3]

#optionally you can add an if statement like this
half_of_positive_nums = [x/2 for x in nums if x>=0] #[2, 4.5, 0.5, 4]

Example 2: list comprehension python 3

number_list = [x for x in range(10) if x % 2 == 0]
print(number_list)