numpy scale code example

Example 1: how to scale an array between two values python

import numpy as np

a = np.random.rand(3,2)

# Normalised [0,1]
b = (a - np.min(a))/np.ptp(a)

# Normalised [0,255] as integer: don't forget the parenthesis before astype(int)
c = (255*(a - np.min(a))/np.ptp(a)).astype(int)        

# Normalised [-1,1]
d = 2.*(a - np.min(a))/np.ptp(a)-1

Example 2: scale in numpy

abs_max = np.amax(np.abs(unnormalized_array))
normalized_array = unnormalized_array * (4.0 / abs_max)