在用R语言做各种事物时，用户自定义函数是不可或缺的。这期来讲讲如何自定义R的function。首先要介绍的是function的基本框架：
myfunction <- function(arg1, arg2, ... ){ statements return(object) }- 1
- 2
- 3
- 4
- 函数名称为myfunction
- arg1，arg2 为参数
- statements 为函数语句
- return(object)返回结果
两个例子
例子一：随机数产生，画图
function1 <- function(x,y){ plot(x,y) return(x+y) } > x <- rnorm(10) > y <- rnorm(10,2,3) > function1(x,y) [1] 1.5828019 0.2661017 -2.7666838 9.9395144 3.3619610 -0.9452065 -6.4638374 -0.3288615 1.1402272 [10] -0.1285368- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
出结果图
例子二：判断、条件句
function2 <- function(x,npar=TRUE,print=TRUE) { if (!npar) { center <- mean(x); spread <- sd(x) } else { center <- median(x); spread <- mad(x) } if (print & !npar) { cat("Mean=", center, "\n", "SD=", spread, "\n") } else if (print & npar) { cat("Median=", center, "\n", "MAD=", spread, "\n") } result <- list(center=center,spread=spread) return(result) } > x<-rnorm(10,0,1) > function2(x) Median= 0.2469624 MAD= 1.161068 $center [1] 0.2469624 $spread [1] 1.161068