How to multiply individual elements of a list with a number?

Question

S = [22, 33, 45.6, 21.6, 51.8]
P = 2.45

Here S is an array

How will I multiply this and get the value?

SP = [53.9, 80.85, 111.72, 52.92, 126.91]

Asked By: bharath

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Answer 1

You can use built-in map function:

result = map(lambda x: x * P, S)

or list comprehensions that is a bit more pythonic:

result = [x * P for x in S]

Answered By: KL-7

Answer 2

In NumPy it is quite simple

import numpy as np
P=2.45
S=[22, 33, 45.6, 21.6, 51.8]
SP = P*np.array(S)

I recommend taking a look at the NumPy tutorial for an explanation of the full capabilities of NumPy’s arrays:

Answered By: JoshAdel

Answer 3

If you use numpy.multiply

S = [22, 33, 45.6, 21.6, 51.8]
P = 2.45
multiply(S, P)

It gives you as a result

array([53.9 , 80.85, 111.72, 52.92, 126.91])

Answered By: DKK

Answer 4

import operator
from itertools import repeat


def scalar_multiplication(vector, scalar):
    yield from map(operator.mul, vector, repeat(scalar))

Example of usage:

>>> v = [1, 2, 3, 4]
>>> c = 3
>>> list(scalar_multiplication(v, c))
[3, 6, 9, 12]

Answered By: Georgy

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