How to create an immutable Numpy array? : Pythoneo

Let’s check how to create an immutable Numpy array.

Setting writeable flag

To make the array immutable, you need to set the writeable flag to false.

import numpy as np

my_array = np.array([1, 2, 3])
print(my_array)

my_array[1] = 5
print(my_array)

my_array.flags.writeable = False

my_array[2] = 6
print(my_array)

As you can see, it is not possible to change the array. Python displays assignment destination is a read-only ValueError.

Traceback (most recent call last):
  File "C:\Users\pythoneo\PycharmProjects\pythoneoProject\immutable_array_python.py", line 11, in 
    my_array[2] = 6
ValueError: assignment destination is read-only

Setting a writeable flag rendered your code immutable.To turn off read-only mode, you need to set the writeable flag back to true.

Setting write flag

Alternatively, you can set the write flag to false.

import numpy as np

my_array = np.array([1, 2, 3])
print(my_array)

my_array[1] = 5
print(my_array)

my_array.setflags(write=False)

my_array[2] = 6
print(my_array)

Python displays ValueError as well. The full error message is as follows:

Traceback (most recent call last):
  File "C:\Users\pythoneo\PycharmProjects\pythoneoProject\immutable_array_python.py", line 11, in 
    my_array[2] = 6
ValueError: assignment destination is read-only

Set the write flag back to true to allow editing.