You can use the following methods to replace elements in a NumPy array:
Method 1: Replace Elements Equal to Some Value
#replace all elements equal to 8 with a new value of 20 my_array[my_array == 8] = 20
Method 2: Replace Elements Based on One Condition
#replace all elements greater than 8 with a new value of 20 my_array[my_array > 8] = 20
Method 3: Replace Elements Based on Multiple Conditions
#replace all elements greater than 8 or less than 6 with a new value of 20 my_array[(my_array > 8) | (my_array < 6)] = 20
The following examples show how to use each method in practice with the following NumPy array:
import numpy as np
#create array
my_array = np.array([4, 5, 5, 7, 8, 8, 9, 12])
#view array
print(my_array)
[ 4 5 5 7 8 8 9 12]
Method 1: Replace Elements Equal to Some Value
The following code shows how to replace all elements in the NumPy array equal to 8 with a new value of 20:
#replace all elements equal to 8 with 20
my_array[my_array == 8] = 20
#view updated array
print(my_array)
[ 4 5 5 7 20 20 9 12]
Method 2: Replace Elements Based on One Condition
The following code shows how to replace all elements in the NumPy array greater than 8 with a new value of 20:
#replace all elements greater than 8 with 20
my_array[my_array > 8] = 20
#view updated array
print(my_array)
[ 4 5 5 7 8 8 20 20]
Method 3: Replace Elements Based on Multiple Conditions
The following code shows how to replace all elements in the NumPy array greater than 8 or less than 6 with a new value of 20:
#replace all elements greater than 8 or less than 6 with a new value of 20
my_array[(my_array > 8) | (my_array < 6)] = 20
#view updated array
print(my_array)
[20 20 20 7 8 8 20 20]
Additional Resources
The following tutorials explain how to perform other common operations in NumPy:
How to Calculate the Mode of NumPy Array
How to Find Index of Value in NumPy Array
How to Map a Function Over a NumPy Array
