numpy.ma.notmasked_edges

numpy.ma.notmasked_edges(a, axis=None)

Find the indices of the first and last unmasked values along an axis.

If all values are masked, return None. Otherwise, return a list of two tuples, corresponding to the indices of the first and last unmasked values respectively.

Parameters :

a : array_like

The input array.

axis : int, optional

Axis along which to perform the operation. If None (default), applies to a flattened version of the array.

Returns :

edges : ndarray or list

An array of start and end indexes if there are any masked data in the array. If there are no masked data in the array, edges is a list of the first and last index.

See also

flatnotmasked_contiguous, flatnotmasked_edges, notmasked_contiguous

Examples

>>> a = np.arange(9).reshape((3, 3))
>>> m = np.zeros_like(a)
>>> m[1:, 1:] = 1

>>> ma = np.ma.array(a, mask=m)
>>> np.array(ma[~ma.mask])
array([0, 1, 2, 3, 6])

>>> np.ma.extras.notmasked_edges(ma)
array([0, 6])