R語言 -- 交并補(bǔ)：intersect、union、setdiff、Reduce多重操作

> # 交并補(bǔ)
> a = seq(0, 40, 4); a
 [1]  0  4  8 12 16 20 24 28 32 36 40
> b = seq(0, 40, 5); b
[1]  0  5 10 15 20 25 30 35 40
> 
> # 交集
> intersect(a,b)
[1]  0 20 40
> 
> # 并集
> union(a,b)
 [1]  0  4  8 12 16 20 24 28 32 36 40  5 10 15 25 30 35
> 
> # a 減去 a交b
> setdiff(a,b)
[1]  4  8 12 16 24 28 32 36
> 
> # b 減去 a交b
> setdiff(b,a)
[1]  5 10 15 25 30 35
> 
> # 多個(gè)集合之間操作
> Reduce(union,  list(v1 = c("a","b","c","d"),
+                         v2 = c("a","b","e"),
+                         v3 = c("a","f","g"),
+                         v4 = c("a","f","e","g"))
+ )
[1] "a" "b" "c" "d" "e" "f" "g"
> 
> Reduce(intersect,  list(v1 = c("a","b","c","d"),
+                     v2 = c("a","b","e"),
+                     v3 = c("a","f","g"),
+                     v4 = c("a","f","e","g"))
+ )
[1] "a"
> 
> Reduce(setdiff,  list(v1 = c("a","b","c","d"),
+                         v2 = c("a","b","e"),
+                         v3 = c("a","f","g"),
+                         v4 = c("a","f","e","g"))
+ )
[1] "c" "d"