Python | numpy.putmask() method

With the help of numpy.putmask() method, we can change the elements in an array with the help of condition and given value by using numpy.putmask() method.

Syntax : numpy.putmask(array, condition, value)
Return : Return the array having new elements according to value.

Example #1 :
In this example we can see that by using numpy.putmask() method, we are able to get the new array with the help of a given condition and value.

# import numpy
import numpy as np

# using numpy.putmask() method
arr = np.array([1, 2, 3, 4, 5, 6])
np.putmask(arr, arr % 2 == 0, 0)

print(arr)

Output :

array([1, 0, 3, 0, 5, 0])

Example #2 :

# import numpy
import numpy as np

# using numpy.putmask() method
arr = np.array([[1, 2, 3],
                [3, 2, 1],
                [1, 2, 3]])

np.putmask(arr, arr>2, 4)

print(arr)

Output :

[[1 2 4]
[4 2 1]
[1 2 4]]