numpy.ma.masked_array.hardmask

property

property ma.masked_array.hardmask

Specifies whether values can be unmasked through assignments.

By default, assigning definite values to masked array entries will unmask them. When hardmask is True, the mask will not change through assignments.

See also

ma.MaskedArray.harden_mask

ma.MaskedArray.soften_mask

Examples

>>> x = np.arange(10)
>>> m = np.ma.masked_array(x, x>5)
>>> assert not m.hardmask

Since m has a soft mask, assigning an element value unmasks that element:

>>> m[8] = 42
>>> m
masked_array(data=[0, 1, 2, 3, 4, 5, --, --, 42, --],
             mask=[False, False, False, False, False, False,
                   True, True, False, True],
       fill_value=999999)

After hardening, the mask is not affected by assignments:

>>> hardened = np.ma.harden_mask(m)
>>> assert m.hardmask and hardened is m
>>> m[:] = 23
>>> m
masked_array(data=[23, 23, 23, 23, 23, 23, --, --, 23, --],
             mask=[False, False, False, False, False, False,
                   True, True, False, True],
       fill_value=999999)