x=1:100
(x=1:100)
sample(x,20)
set.seed(0);sample(1:10,3)
z=sample(1:20000,1000)
z[1:10]
y=c(1,3,7,3,4,2)
z[y]
(z=sample(x,100,rep=T))
(z1=unique(z))
length(z1)
xz=setdiff(x,z)
sort(union(xz,z))
setequal(union(xz,z),x)
intersect(1:10,7:50)