小编Mir*_*zig的帖子

如果我有这样的数据帧:

neu <- data.frame(test1 = c(1,2,3,4,5,6,7,8,9,10,11,12,13,14), 
                  test2 = c("a","b","a","b","c","c","a","c","c","d","d","f","f","f"))
neu
   test1 test2
1      1     a
2      2     b
3      3     a
4      4     b
5      5     c
6      6     c
7      7     a
8      8     c
9      9     c
10    10     d
11    11     d
12    12     f
13    13     f
14    14     f

而且我想只选择那些因子水平test2出现超过三次的值,那么最快的方法是什么？

非常感谢,在之前的问题中没有找到正确的答案.