table1
| id | cousult | time1 | last_time |
|---|---|---|---|
| 1 | 278 | 2 | 0 |
| 2 | 899 | 2 | 0 |
table2
| department_id | time2 |
|---|---|
| 1 | 5 |
| 3 | 7 |
| 4 | 9 |
for i in range(len(table1)):
for ii in range(len(table2)):
if table1['id'][i] == table2['department_id'][ii] and \
table1['time1'][i] <= table2['time2'][ii]:
table1['last_time'][i] = table2['time2'][ii]
问题1 ： 两张表数据量比较大的时候，循环嵌套导致运行时间较慢。
希望能使用pandas解决，有知道怎么解决吗