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# Numpy MaskedArray.dot() function | Python

• 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)`

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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 :

 `# 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 :

 `# 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]]

```

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