code: def get_row_dict(self, row_idx):
          
  
          try:
              row = self._rows[row_idx]
          except TypeError:
              row = self._rows[self._row_name_idx[row_idx]]
  
          if isinstance(row, dict):
              return row
  
          else:
              if row_idx not in self._row_memo:
                  self._row_memo[row_idx] = dict((self._column_name_list[idx], v) for idx, v in enumerate(row) if v != self._default_value)
  
              return self._row_memo[row_idx]
docs: Return a dictionary representation for a matrix row
  
          :param row_idx: which row
          :return: a dict of feature keys/values, not including ones which are the default value