范围内的cumsum(python，pandas)

我有一个df，在这里，我希望求和在0到6的范围内.其中超过6的总和将转为0.adj_cumsum列就是我想要的.不过，我用循环搜索并找到了几篇帖子，因为我的帖子更简单，所以我想知道是否有一种不那么复杂或更新的方法.

+----+-------+------+----------+----------------+--------+------------+
|    | month | days | adj_days | adj_days_shift | cumsum | adj_cumsum |
+----+-------+------+----------+----------------+--------+------------+
|  0 | jan   |   31 |        3 |              0 |      0 |          0 |
|  1 | feb   |   28 |        0 |              3 |      3 |          3 |
|  2 | mar   |   31 |        3 |              0 |      3 |          3 |
|  3 | apr   |   30 |        2 |              3 |      6 |          6 |
|  4 | may   |   31 |        3 |              2 |      8 |          1 |
|  5 | jun   |   30 |        2 |              3 |     11 |          4 |
|  6 | jul   |   31 |        3 |              2 |     13 |          6 |
|  7 | aug   |   31 |        3 |              3 |     16 |          2 |
|  8 | sep   |   30 |        2 |              3 |     19 |          5 |
|  9 | oct   |   31 |        3 |              2 |     21 |          0 |
| 10 | nov   |   30 |        2 |              3 |     24 |          3 |
| 11 | dec   |   31 |        3 |              2 |     26 |          5 |
+----+-------+------+----------+----------------+--------+------------+

data = {"month": ['jan','feb','mar','apr',
                 'may','jun','jul','aug',
                 'sep','oct','nov','dec'], 
       "days": [31,28,31,30,31,30,31,31,30,31,30,31]}
df = pd.DataFrame(data)

df['adj_days'] = df['days'] - 28
df['adj_days_shift'] = df['adj_days'].shift(1)
df['cumsum'] = df.adj_days_shift.cumsum()
df.fillna(0, inplace=True)

恳请告知