重新排列周末后将列移位以按数字顺序具有相同的数字python

Question

日期采用日期时间格式 周末的天数必须相同，其余的按数字顺序向下移动。 df1

   Date         Number
0. 12-10-2018   1
1. 13-10-2018   2 
2. 14-10-2018   3
3. 15-10-2018   4
4. 16-10-2018   5
5. 17-10-2018   6
6. 18-10-2018   7
7. 18-10-2018   8
8. 19-10-2018   9

我的代码：

   i = 1
   df1['DAY'][0] == 1
   for i in range(len(df1[0])):
       if df1[0][i].weekday() == 4:

           df1['DAY'].iloc[i+1] = df1['DAY'].iloc[i]
       elif df1[0][i].weekday() == 5:
           df1['DAY'].iloc[i+1] = df1['DAY'].iloc[i]

这给了我输出我的电话号码的信息：

df1

   Date         Number
0. 12-10-2018   1
1. 13-10-2018   1 
2. 14-10-2018   1
3. 15-10-2018   4
4. 16-10-2018   5
5. 17-10-2018   6
6. 18-10-2018   7
7. 19-10-2018   8
8. 20-10-2018   8

我需要输出为：

df1

   Date         Number
0. 12-10-2018   1
1. 13-10-2018   1 
2. 14-10-2018   1
3. 15-10-2018   2
4. 16-10-2018   3
5. 17-10-2018   4
6. 18-10-2018   5
7. 19-10-2018   6
8. 20-10-2018   6

非常感谢