Custom Packages in R: A Step-by-Step Tutorial

The process of creating their own R package using the devtools and roxygen2 packages

R is a powerful and flexible programming language for data analysis and visualization. One of the advantages of R is that it allows users to create and share their packages, which are collections of functions, data, and documentation that can extend the functionality of R. Creating your R package can help you organize your code, reuse your functions, and share your work with others.

Step 1: Create a package skeleton

The first step is to create a package skeleton, which is a directory that contains the basic structure and files of a package. To do this, we can use the create () function from the devtools package. For example, if we want to create a package called mypackage, we can run the code in RStudio. This will create a directory called mypackage in our current working directory, and populate it with some files and folders, such as DESCRIPTION, NAMESPACE, R, and man. These files and folders are essential for a package.

Step 2: Add functions and data

The next step is to add the functions and data that we want to include in our package. We can write our functions in R scripts and save them in the R folder of our package directory. For example, if we have a function called hello that prints a greeting message, we can save it in a file called hello.

We can also add data sets to our package by saving them as RData files in the data folder of our package directory. For example, if we have a data frame called cars that contains some information about cars, we can save it in a file called cars.

Step 3: Add documentation

The third step is to add documentation for our package, which is the information that describes what our package does, how to use it, and what are the inputs and outputs of our functions and data. Documentation is important for users to understand and use our package correctly.

To add documentation, we can use the roxygen2 package, which allows us to write documentation comments in our R scripts, and then automatically generate the corresponding manual files in the man folder of our package directory. The manual files are in Rd format, which is a standard format for R documentation.

To use roxygen2, we need to add some special comments, starting with #' , before each function or data set that we want to document. These comments should include some tags, such as @name, @title, @description, @param, @return, @export, etc., that provide the relevant information for the documentation.

Step 4: Build and install the package

The final step is to build and install our package, which means compiling our package into a binary or source file that can be installed and loaded in R. To do this, we can use the build () and install() functions from the devtools package. This will create a file called mypackage_0.0.0.9000.tar.gz in our current working directory, which is the source file of our package. It will also install our package in our local library, and make it available for use in R.