Python mutability numpy array demo

mutability_test.py

import numpy as np

# How NOT to do it!!!
x = np.zeros([2,2]) # NumPy array, is mutable
print(id(x))        # ID for x
a = x               # a is not a copy of x, it is the same variable in memory 
print(id(a))        # ID of a == ID of x
x[0,0] = 1          # Updating values in x
b = x               # b is not a copy of x, it is the same variable in memory 
print(id(a))        # ID of a == ID of x
print(x)
print(a)
print(b)

# How to do it
x = np.zeros([2,2]) # NumPy array, is mutable
print(id(x))        # ID for x
a = x * 1           # a is x multiplied by 1, thus it is not the same variable in memory 
print(id(a))        # ID of a != ID of x
x[0,0] = 1          # Updating values in x
b = x * 1           # b is x multiplied by 1, thus it is not the same variable in memory 
print(id(a))        # ID of a != ID of x
print(x)
print(a)
print(b)