# Count the number of masked elements along specific axis

To count the number of masked elements along specific axis, use the ma.MaskedArray.count_masked() method. The axis is set using the "axis" parameter. The method returns the total number of masked elements (axis=None) or the number of masked elements along each slice of the given axis.

The axis parameter is the axis along which to count. If None (default), a flattened version of the array is used.

## Steps

At first, import the required library −

import numpy as np
import numpy.ma as ma

Creating a 4x4 array with int elements using the numpy.arange() method −

arr = np.arange(16).reshape((4,4))
print("Array...", arr)
print("Array type...", arr.dtype)

Get the dimensions of the Array −

print("Array Dimensions...",arr.ndim)


Get the shape of the Array −

print("Our Masked Array Shape...",arr.shape)

Get the number of elements of the Array −

print("Elements in the Masked Array...",arr.size)


arr = ma.array(arr)

arr[3, 3] = ma.masked

To count the number of masked elements along specific axis, use the ma.MaskedArray.count_masked() method. The axis is set using the "axis" parameter:

print("Result (number of masked elements)...",ma.count_masked(arr, axis = 1))


## Example

# Python ma.MaskedArray - Count the number of masked elements along specific axis

import numpy as np
import numpy.ma as ma

# Creating a 4x4 array with int elements using the numpy.arange() method
arr = np.arange(16).reshape((4,4))
print("Array...", arr)
print("Array type...", arr.dtype)

# Get the dimensions of the Array
print("Array Dimensions...",arr.ndim)
print("Our Array type...", arr.dtype)

# Get the shape of the Array

# Get the number of elements of the Array

arr = ma.array(arr)

# The axis is set using the "axis" parameter
print("Result (number of masked elements)...",ma.count_masked(arr, axis = 1))

## Output

Array...
[[ 0 1 2 3]
[ 4 5 6 7]
[ 8 9 10 11]
[12 13 14 15]]

Array type...
int64

Array Dimensions...
2

Our Array type...
int64

(4, 4)

16

[1 1 2 3]

Updated on: 03-Feb-2022

66 Views

Get certified by completing the course