本次总结来源网络，有多处参考
在R语言中，去掉重复数据的函数是：duplicated
删掉所有列中数据一样的：
>test <- data.frame(
x1 = c(1,2,3,4,5,1,3,5),
x2 = c("a","b","c","d","e","a","b","e"),
x3 = c("a","b","c","d","e","a","c","e"))
> test
x1 x2 x3
1 1 a a
2 2 b b
3 3 c c
4 4 d d
5 5 e e
6 1 a a
7 3 b c
8 5 e e
> test[!duplicated(test),] #删掉所有列上都重复的
x1 x2 x3
1 1 a a
2 2 b b
3 3 c c
4 4 d d
5 5 e e
7 3 b c
选择性的删除重复的
> test[!duplicated(test[,c(2,3)]),]
x1 x2 x3
1 1 a a
2 2 b b
3 3 c c
4 4 d d
5 5 e e
7 3 b c
