R语言list的特点：It has length, [[ and [ methods, and is recursive because list can contain other list!上图显示了操作符 [[和[的区别！---[返回结果依旧是一个list但是[[已经不是一个list了
》》具有list属性的类还有
1、call类对象：The first element of the call is the function that gets called. It’s usually the name of a function:
> x <- quote(read.csv("important.csv", row.names = FALSE)) > class(x) [1] "call" > lenth(x)
2、formula 类的对象
dat=data.frame(x1=rnorm(100,m=50),x2=rnorm(100,m=50),x3=rnorm(100,m=50),x4=rnorm(100,m=50),y=rnorm(100)) m2=lm(y~log(x1)+x2*x3,data=dat) newFmla=formula(m2)
> class(newFmla) [1] "formula" > length(newFmla) [1] 3 > newFmla[1] `~`() > newFmla[2] y() > newFmla[3] (log(x1) + x2 * x3)()
原文：http://www.cnblogs.com/amazement/p/4892303.html