R中数据帧的计数功能

I have the following data frame:

我有以下数据框:

> Mice
        Blood  States  Minute
1       0.875     X0 0.8352569
2       0.875     A2 0.7551901
3       0.625     X0 1.4508139
4       0.625     A1 0.7876343
5       0.375     X0 1.1345252
6       0.125     X0 0.8699363
7       0.375     X0 0.9378742
8       1.125     H1 0.9769522
9       0.625     X0 0.4716321
10      0.875     H1 0.9935999
11      0.625     X0 1.0025917
12      0.375     A1 1.0703999
13      0.375     X0 1.3044854
14      0.875     H1 0.6720436
15      0.875     A1 1.0431863
>