R语言中取交集函数intersect

1、测试数值

> dat1 <- 1:8
> dat2 <- 3:10
> intersect(dat1, dat2)   ## 直接取两个数值型的交集
[1] 3 4 5 6 7 8

 

2、数值有重复的情况

> dat1 <- c(2, 3, 2, 4, 5, 3, 6, 3, 4, 8)
> dat2 <- c(7, 3, 4, 9, 2, 10, 5)
> intersect(dat1, dat2)   ## intersect可以直接去重复
[1] 2 3 4 5
> intersect(dat2, dat1)   ## 交换两个数据的位置，输出的顺序有差异， 但是结果一致
[1] 3 4 2 5

 

3、字符串的情况

> dat1 <- c("x", "a", "b", "b", "a", "d","c", "f", "d")
> dat2 <- c("c", "b","b", "g", "y", "d", "d", "m")
> intersect(dat1, dat2)     ## 对字符串同样适用
[1] "b" "d" "c"
> intersect(dat2, dat1)
[1] "c" "b" "d"

 

4、数值和字符串之间的比较

> dat1 <- c(3, 5, 1, 2,2, 3, 3, 7, 5, 8, 3)
> dat2 <- c("2", "3", "9", "5", "6", "1", "10", "1")
> class(dat1)
[1] "numeric"
> class(dat2)
[1] "character"
> intersect(dat1, dat2)   ## intersect函数可以实现字符串与数字的比较， 而且返回值的属性与两个比较数据的位置有关，输出数据类型为第二个数据的属性
[1] "3" "5" "1" "2"
> intersect(dat2, dat1)
[1] 2 3 5 1