R: How to add a dummy variable for counting the number of appearance

Question

Here is my dataframe:

Number    Action
1         Running
2         Running
3         Swimming
4         Eating
5         Eating

I would like to add a variable to count the number of appearance, like this:

Number    Action    Count
1         Running   1
2         Running   2
3         Swimming  1
4         Eating    1
5         Eating    2

Answer 1

这是使用memcmp

的一种方法

dplyr

^{由reprex package（v0.2.1）于2018-11-26创建}