R-introduction

length(x)  # 给出元素个数

prod（x） #给出元素积
sum（x）#元素和
mean(x)=sum(x)/length(x)
var(x)=sum((x-mean(x))^2/(length(x)-1)

sort（x） #按升序重新排列

seq(1,10,length=10,by=2)

> labs <- paste(c("x","y"),1:10,sep="")
> labs
 [1] "x1"  "y2"  "x3"  "y4"  "x5"  "y6"  "x7"  "y8"  "x9"  "y10"