这开始于活动列表。我首先建立了一个类似于下面的矩阵来表示所有活动，然后我反转以显示所有不活动状态，然后再构建以下矩阵，其中零表示活动，大于零的值表示下一个活动的天数。
+------+------------+------------+------------+------------+------------+------------+------------+------------+------------+
| Item | 01/08/2020 | 02/08/2020 | 03/08/2020 | 04/08/2020 | 05/08/2020 | 06/08/2020 | 07/08/2020 | 08/08/2020 | 09/08/2020 |
+------+------------+------------+------------+------------+------------+------------+------------+------------+------------+
| A | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 |
| B | 3 | 2 | 1 | 0 | 0 | 3 | 2 | 1 | 0 |
| C | 0 | 2 | 1 | 0 | 1 | 0 | 0 | 0 | 0 |
| D | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | 0 |
| E | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 |
+------+------------+------------+------------+------------+------------+------------+------------+------------+------------+
现在我需要为每个项目找到合适的间隔。例如，在这种情况下，我想查找所有持续时间至少为3天的间隔。
+------+------------+------------+------------+------------+
| Item | 1_START | 1_END | 2_START | 2_END |
+------+------------+------------+------------+------------+
| A | NaN | NaN | NaN | NaN |
| B | 01/08/2020 | 03/08/2020 | 06/08/2020 | 08/08/2020 |
| C | NaN | NaN | NaN | NaN |
| D | 01/08/2020 | 07/08/2020 | NaN | NaN |
| E | 01/08/2020 | NaN | NaN | NaN |
+------+------------+------------+------------+------------+
实际上，数据的宽度为700+列，而行则为1000+。如何有效地做到这一点？