Numpy MaskedArray.dot() function | Python (original) (raw)

Last Updated : 18 Oct, 2019

numpy.MaskedArray.dot() function is used to calculate the dot product of two mask arrays.

Syntax : numpy.ma.dot(arr1, arr2, strict=False) Parameters: **arr1, arr2:**[ ndarray] Inputs arrays.strict : [bool, optional] Whether masked data are propagated (True) or set to 0 (False) for the computation. Default is False.Return : [ ndarray] The dot product of arr1 and arr2.

Code #1 :

Python3 `

Python program explaining

numpy.MaskedArray.dot() method

importing numpy as geek

and numpy.ma module as ma

import numpy as geek import numpy.ma as ma

creating input arrays

in_arr1 = geek.array([[1, 2], [ 3, 4]]) print ("1st Input array : ", in_arr1)

in_arr2 = geek.array([[-1, -2], [ -3, -4]]) print ("2nd Input array : ", in_arr2)

Now we are creating masked array.

by making entry as invalid

mask_arr1 = ma.masked_array(in_arr1, mask = [[ 1, 0], [ 0, 1]])
print ("1st Masked array : ", mask_arr1)

mask_arr2 = ma.masked_array(in_arr2, mask =[[ 0, 1], [ 0, 0]])
print ("2nd Masked array : ", mask_arr2)

applying MaskedArray.dot methods

to masked array

out_arr = ma.dot(mask_arr1, mask_arr2)
print ("Dot product of two arrays : ", out_arr)

`

Output:

1st Input array : [[1 2] [3 4]] 2nd Input array : [[-1 -2] [-3 -4]] 1st Masked array : [[-- 2] [3 --]] 2nd Masked array : [[-1 --] [-3 -4]] Dot product of two arrays : [[-6 -8] [-3 --]]

Code #2 :

Python3 `

Python program explaining

numpy.MaskedArray.dot() method

importing numpy as geek

and numpy.ma module as ma

import numpy as geek import numpy.ma as ma

creating input arrays

in_arr1 = geek.array([[1, 2], [ 3, -1], [ 5, -3]]) print ("1st Input array : ", in_arr1)

in_arr2 = geek.array([[1, 0, 3], [ 4, 1, 6]]) print ("2nd Input array : ", in_arr2)

Now we are creating masked array.

by making entry as invalid

mask_arr1 = ma.masked_array(in_arr1, mask = [[ 1, 0], [ 0, 1], [ 0, 0]])
print ("1st Masked array : ", mask_arr1)

mask_arr2 = ma.masked_array(in_arr2, mask =[[ 0, 0, 0], [ 0, 0, 1]])
print ("2nd Masked array : ", mask_arr2)

applying MaskedArray.dot methods

to masked array

out_arr = ma.dot(mask_arr1, mask_arr2)
print ("Dot product of two arrays : ", out_arr)

`

Output:

1st Input array : [[ 1 2] [ 3 -1] [ 5 -3]] 2nd Input array : [[1 0 3] [4 1 6]] 1st Masked array : [[-- 2] [3 --] [5 -3]] 2nd Masked array : [[1 0 3] [4 1 --]] Dot product of two arrays : [[8 2 --] [3 0 9] [-7 -3 15]]