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# Numpy MaskedArray.masked_equal() function | Python

• Last Updated : 27 Sep, 2019

In many circumstances, datasets can be incomplete or tainted by the presence of invalid data. For example, a sensor may have failed to record a data, or recorded an invalid value. The `numpy.ma` module provides a convenient way to address this issue, by introducing masked arrays.Masked arrays are arrays that may have missing or invalid entries.

`numpy.MaskedArray.masked_equal()` function is used to mask an array where equal to a given value.

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Syntax : `numpy.ma.masked_equal(arr, value, copy=True)`

Parameters:
arr : [ndarray] Input array which we want to mask.
value : [int] Element of masked array which we want to mask.
copy : [bool] If True (default) make a copy of arr in the result. If False modify arr in place and return a view.

Return : [ MaskedArray] The result of masking.

Code #1 :

 `# Python program explaining``# numpy.MaskedArray.masked_equal() method `` ` `# importing numpy as geek ``# and numpy.ma module as ma``import` `numpy as geek``import` `numpy.ma as ma`` ` `# creating input array ``in_arr ``=` `geek.array([``1``, ``2``, ``3``, ``-``1``, ``2``])``print` `(``"Input array : "``, in_arr)`` ` `# applying MaskedArray.masked_equal methods ``# to input array where value = 2``mask_arr ``=` `ma.masked_equal(in_arr, ``2``)``print` `(``"Masked array : "``, mask_arr)`
Output:
```Input array :  [ 1  2  3 -1  2]
Masked array :  [1 -- 3 -1 --]
```

Code #2 :

 `# Python program explaining``# numpy.MaskedArray.masked_equal() method `` ` `# importing numpy as geek ``# and numpy.ma module as ma``import` `numpy as geek``import` `numpy.ma as ma`` ` `# creating input array ``in_arr ``=` `geek.array([``2e8``, ``3e``-``5``, ``-``45.0``, ``2e5``, ``5e2``])``print` `(``"Input array : "``, in_arr)`` ` `# applying MaskedArray.masked_equal methods ``# to input array where value = 5e2``mask_arr ``=` `ma.masked_equal(in_arr, ``5e2``)``print` `(``"Masked array : "``, mask_arr)`
Output:
```Input array :  [ 2.0e+08  3.0e-05 -4.5e+01  2.0e+05  5.0e+02]
Masked array :  [200000000.0 3e-05 -45.0 200000.0 --]
```

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