How to return a mask or nomask of a masked array in Python
Overview
The numpy.ma.getmask() method in Python is used to return the mask or no mask values of a masked array. This is done by returning a Boolean array, which holds the result, of the same shape as the input array.
Syntax
The ma.getmask() method uses the syntax below:
ma.getmask(a)
Syntax for the ma.getmask() function in Python
Parameters
The ma.getmask() method takes a single parameter value, a, which represents the input array (possibly masked) for which the mask is to be obtained.
Return values
The ma.getmask() method returns an array of Boolean values indicating the mask (True) or nomask (False) elements of the input array.
Example
Below, we see an example of the ma.getmask() method:
import numpy.ma as ma# creating a masked arraya = ma.arange(8).reshape(4,2)# masking the element in the second row but the second columna[1, 1] = ma.masked# masking the elements in the third rowa[2, :] = ma.masked# implementing the ma.getmask() methodb = ma.getmask(a)print(a)print(b)
Explanation
In the code above, we do the following:
- Line 1: We import the
numpy.mamodule. - Line 3: We create an input array,
a. - Line 6: We mask the element in the second row on the second column of the input array.
- Line 9: We mask the elements of the third row of the input array.
- Line 12: We obtain the mask and nomask values of the input array by using the
ma.getmask()function. The result is assigned to a variable,b. - Lines 14–15: We print the input array,
aand the obtained array,b.