@pimms.value<EOL><INDENT>def gray_indices(lh_gray_indices, rh_gray_indices):<DEDENT>
if lh_gray_indices is None and rh_gray_indices is None: return None<EOL>elif lh_gray_indices is None: return rh_gray_indices<EOL>elif rh_gray_indices is None: return lh_gray_indices<EOL>else:<EOL><INDENT>gis = tuple([np.concatenate(pair) for pair in zip(lh_gray_indices, rh_gray_indices)])<EOL>for row in gis: row.setflags(write=False)<EOL>return gis<EOL><DEDENT>
sub.gray_indices is equivalent to numpy.where(sub.gray_mask).