NumPy参考 >数组对象 >Masked array operations > numpy.ma.count_masked
numpy.ma.
count_masked
(arr, axis=None)[source]¶Count the number of masked elements along the given axis.
An array with (possibly) masked elements.
Axis along which to count. If None (default), a flattened version of the array is used.
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])