How to Multiply a List by a Scalar in Python

If you need to multiply a list by a scalar in Python, then you can do one of the following:

Option 1 – Using List Comprehensions

li = [1,2,3,4]
multiple = 2.5
li = [x*multiple for x in li]
print(li)

Output: [2.5, 5.0, 7.5, 10.0]

Option 2 – Using map()

li = [1,2,3,4]
multiple = 2.5
def multiply(le):
    return le*multiple

li = list(map(multiply,li))
print(li)

Output: [2.5, 5.0, 7.5, 10.0]

Option 3 – Using Lambda Functions

li = [1,2,3,4]
multiple = 2.5
li = list(map(lambda x: x*multiple, li))
print(li)

Output: [2.5, 5.0, 7.5, 10.0]

Option 4 – Using Numpy Arrays

import numpy as np
li = [1,2,3,4]
multiple = 2.5
arr = np.array(li)
arr = arr * multiple
li = arr.tolist()
print(li)

Output: [2.5, 5.0, 7.5, 10.0]