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# numpy.ma.count_masked

`numpy.ma.``count_masked`(arr, axis=None)

  Count the number of masked elements along the given axis.

  Parameters: | arr : array_like An array with (possibly) masked elements. axis : int, optional Axis along which to count. If None (default), a flattened version of the array is used.
  Returns: | count : int, ndarray The total number of masked elements (axis=None) or the number of masked elements along each slice of the given axis.

  See also

  `MaskedArray.count`
    Count non-masked elements.

  Examples

      >>> import numpy.ma as ma
      >>> a = np.arange(9).reshape((3,3))
      >>> a = ma.array(a)
      >>> a[1, 0] = ma.masked
      >>> a[1, 2] = ma.masked
      >>> a[2, 1] = ma.masked
      >>> a
      masked_array(data =
       [[0 1 2]
       [-- 4 --]
       [6 -- 8]],
            mask =
       [[False False False]
       [ True False  True]
       [False  True False]],
            fill_value=999999)
      >>> ma.count_masked(a)
      3

  When the axis keyword is used an array is returned.

      >>> ma.count_masked(a, axis=0)
      array([1, 1, 1])
      >>> ma.count_masked(a, axis=1)
      array([0, 2, 1])