Introduction
This document illustrates how to create an R package by using a simple "hello world" example. This simple package (helloWorld) contains two functions: hello(), which prints a hello message, and goodbye() which takes a single argument and prints a goodbye message plus the argument value.
Defining The Functions
The two functions can be defined using the following steps:
1) Open an R command prompt
2) Paste the following code into R:
hello <- function(){
cat("Hello World!\n")
}
goodbye <- function(message){
cat("Goodbye: ", message, "!\n", sep="")
}
These functions should now be defined in your global namespace and can be executed just like any other function:
> hello()
Hello World!
> goodbye("Sayonara")
Goodbye: Sayonara!
Creating the Package Skeleton
The function package.skeleton() can be used to create an R package from the objects in the workspace. To do this, you will need to call the function using two arguments:
- "name": This is the name of the package, "helloWorld" in this example. package.skeleton() will create a subdirectory in the current working directory with this name. This new directory will contain all the files in the package.
- "list": This is a character vector naming the R objects that should be put into the package, "hello" and "goodbye" in this example.
> package.skeleton(name="helloWorld", list=c("hello", "goodbye"))
Creating directories ...
Creating DESCRIPTION ...
Creating Read-and-delete-me ...
Saving functions and data ...
Making help files ...
Done.
Further steps are described in './helloWorld/Read-and-delete-me'.
The "Read-and-delete-me" file contains information on the additional steps for creating the Package
Note: There are other ways to create an R package using package.skeleton; see the function help file for details.
Additional Resources
Details on writing R packages can be found here: http://cran.r-project.org/doc/manuals/R-exts.pdf