How to Get the Function Code in R

http://fhqdddddd.blog.163.com/blog/static/1869915420104111031148/

R is “open-access”, so I can read and modify the function code for further application. And that is the reason I choose it, use it and love it.

But first, let’s explore how to get the function code.

1. On R Console. function_name + Enter. For example:

> fivenum

function (x, na.rm = TRUE)

{

xna <- is.na(x)

if (na.rm)

x <- x[!xna]

else if (any(xna))

return(rep.int(NA, 5))

x <- sort(x)

n <- length(x)

if (n == 0)

rep.int(NA, 5)

else {

n4 <- floor((n + 3)/2)/2

d <- c(1, n4, (n + 1)/2, n + 1 - n4, n)

0.5 * (x[floor(d)] + x[ceiling(d)])

}

<environment: namespace:stats>

2. function_name.default. For example:

>qqnorm.default

# this is a visible function, a special case of 3 later.

3. For generic functions like “rep”

>t.test

function (x, ...)

UseMethod("t.test")

<environment: namespace:stats>

>methods(“t.test”)

[1] t.test.default* t.test.formula*

Non-visible functions are asterisked

# first, we should known the “methods” used.

>getAnywhere(“t.test.default”) or >stats:::t.test.default or >getS3method(“t.test”,“default”)

# get “t.test.default” code

4. If all the methods discussed above cannot help, just open the R-code(.tar.gz) for the Z-plan.

For more:

In addition, thanks for Dr. Ding’s prompt help and discussion about the “wilcox.test” function code in R.