数据结构如下,我想把数据缺失的地方(空白的地方)换成m,请问用循环怎么做呢?谢谢!
| pos | name | FF047H16622 | FF047H16606 | FF047H16609 | FF047H16642 | FF047H16647 | FF047H16648 | 
| 1 | PZE104000354 | b | b | a | a | b | b | 
| 1 | PZE104000488 |  |  |  |  |  |  | 
| 1 | PZE104000566 |  |  |  |  |  |  | 
| 1 | PZE104000040 | b | b | a | a | b | b | 
| 2 | PZE104001186 | b | b | a | a | b | b | 
| 2 | SYNGENTA2114 | b | b | a | a | b | b | 
| 3 | PZE104005454 |  |  |  |  |  |  |