# Numpy MaskedArray.flatten() function | Python

• Last Updated : 03 Oct, 2019

`numpy.MaskedArray.flatten()` function is used to return a copy of the input masked array collapsed into one dimension.

Syntax : `numpy.ma.flatten(order='C')`

Parameters:
order : [‘C’, ‘F’, ‘A’, ‘K’, optional] Whether to flatten in C (row-major), Fortran (column-major) order, or preserve the C/Fortran ordering from a. The default is ‘C’.

Return : [ ndarray] A copy of the input array, flattened to one dimension.

Code #1 :

 `# Python program explaining``# numpy.MaskedArray.flatten() method ``   ` `# importing numpy as geek  ``# and numpy.ma module as ma ``import` `numpy as geek ``import` `numpy.ma as ma ``   ` `# creating input array of 2 * 2  ``in_arr ``=` `geek.array([[``10``, ``20``], [``-``10``, ``40``]]) ``print` `(``"Input array : "``, in_arr) ``   ` `# Now we are creating a masked array ``# by making one entry as invalid.  ``mask_arr ``=` `ma.masked_array(in_arr, mask ``=``[[ ``1``, ``0``], [ ``0``, ``0``]]) ``print` `(``"Masked array : "``, mask_arr) ``   ` `# applying MaskedArray.flatten methods to make  ``# it a 1D flattened array``out_arr ``=` `mask_arr.flatten() ``print` `(``"Output flattened masked array : "``, out_arr) `

Output:

```Input array :  [[ 10  20]
[-10  40]]
[-10 40]]
Output flattened masked array :  [-- 20 -10 40]
```

Code #2 :

 `# Python program explaining``# numpy.MaskedArray.flatten() 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``]], [[ ``-``4e``-``6``, ``2e5``]]])``print` `(``"Input array : "``, in_arr) ``   ` `# Now we are creating a masked array ``# by making one entry as invalid.  ``mask_arr ``=` `ma.masked_array(in_arr, mask ``=``[[[ ``1``, ``0``]], [[ ``0``, ``0``]]]) ``print` `(``"Masked array : "``, mask_arr) ``   ` `# applying MaskedArray.flatten methods to make  ``# it a 1D masked array``out_arr ``=` `mask_arr.flatten(order ``=``'F'``) ``print` `(``"Output flattened masked array : "``, out_arr)`

Output:

```Input array :  [[[ 2.e+08  3.e-05]]

[[-4.e-06  2.e+05]]]