'Returns row indices that match some column.
The indices returned by this op are ordered so as to be in correspondence
with the output of matched_column_indicator().  For example if
self.matched_column_indicator() is [0,2], and self.matched_row_indices() is
[7, 3], then we know that column 0 was matched to row 7 and column 2 was
matched to row 3.
Returns:
row_indices: int32 tensor of shape [K] with row indices.'

def matched_row_indices(self):

    return self._reshape_and_cast(tf.gather(self._match_results, self.matched_column_indices()))
