How to mask an array where invalid values occur in NumPy

Overview

The masked_invalid() function in NumPy is used to mask an array where invalid values occur. These invalid values could be NaNs or infs.

Syntax

ma.masked_invalid(a)
Syntax for the masked_invalid() function

Parameters

The masked_invalid() function takes a single parameter value, a, which is an array.

Return value

The masked_invalid() function returns a masked array.

Example

# A code to illustrate the masked_invalid() function 



# importing the necessary libraries

import numpy as np

import numpy.ma as ma



# creating an input array

my_array = np.array([1, 2, 3, np.NaN, 5, 6, np.PINF, 8, 9, np.NaN])



# printing the array

print(my_array)



# masking the values greater than 2

mask_array =ma.masked_invalid(my_array, 2)



print(mask_array)

Explanation

  • Line 4–5: We import the necessary library and module.
  • Line 8: We create an input array, my_array, containing some invalid values.
  • Line 11: We print the input array, my_array.
  • Line 14: We mask the invalid values of the input array using the masked_invalid() function. The result is assigned to a variable, mask_array.
  • Line 16: We print the masked array, mask_array.

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