How to multiply individual elements of a list with a number?
PythonNumpyMultiplicationPython Problem Overview
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]
Python Solutions
Solution 1 - Python
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
Solution 2 - Python
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]
Solution 3 - Python
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])
Solution 4 - Python
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]