How to multiply array with a number in python

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]

Georgy

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asked Nov 19, 2011 at 15:19

1

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:

https://scipy.github.io/old-wiki/pages/Tentative_NumPy_Tutorial

Georgy

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answered Nov 19, 2011 at 15:25

JoshAdelJoshAdel

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0

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 Nov 19, 2011 at 15:22

KL-7KL-7

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2

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])

nbro

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answered May 14, 2013 at 17:50

DKKDKK

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Here is a functional approach using map, itertools.repeat and operator.mul:

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 Apr 3, 2019 at 9:34

GeorgyGeorgy

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Posted on: March 12, 2021 by Deven

In this article, you will learn how to multiply array by scalar in python.

Let’s say you have 2 arrays that need to be multiplied by scalar n .

array1 = np.array([1, 2, 3])
array2 = np.array([[1, 2], [3, 4]])
n = 5

Numpy multiply array by scalar

In order to multiply array by scalar in python, you can use np.multiply() method.

import numpy as np
array1 = np.array([1, 2, 3])
array2 = np.array([[1, 2], [3, 4]])
n = 5
np.multiply(array1,n)
np.multiply(array2,n)

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How do you multiply a NumPy array by a number?

How do you multiply an array by a scalar in Python?

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