code: def dict_list_2_matrix(dict_list, columns):
      
      k = len(columns)
      n = len(dict_list)
  
      result = [[None] * k for i in range(n)]
      for i in range(n):
          row = dict_list[i]
          for j in range(k):
              col = columns[j]
              if col in row:
                  result[i][j] = row[col]
              else:
                  result[i][j] = None
      return result
docs: >>> dict_list_2_matrix([{'a': 1, 'b': 2}, {'a': 3, 'b': 4}], ('a', 'b'))
          [[1, 2], [3, 4]]
  
      :param dict_list: 字典列表
      :param columns: 字典的键