Before getting started, you will need to load two packages:

> install.packages("roxygen2")

> install.packages("devtools")

You now want to open File in RStudio and select New Project, which will put you at this point:

Select a new directory as desired, and specify R Package, as shown in the following screenshot:

You will now name your package – I've innovatively called this one package – and select Create Project:

Go to your Files tab in RStudio and you should see several files populated like this:

Notice the folder called R. That is where we will put the R functions for our package. But first, click on Description and fill it out accordingly, and save it. Here is my version, which will be a function to code all missing values in a dataframe to zero:

I've left imports and suggests blank. This is where you would load other packages, such as tidyverse or caret. Now, open up the hello.R function in the R folder, and delete all of it. The following format will work nicely:

Here is the function for our purposes, which just turns all NAs to zero:

#' @title package
#'
#' @description Turns NAs in a dataframe into zeroes
#'
#' @param dataframe
#'
#' @return dataframe
#'
#' @examples
#' dataset <- matrix(sample(c(NA, 1:5), 25, replace = TRUE), 5)
#' df <- as.data.frame(dataset)
#' package::na2zero(df)
#'
#' @export

na2zero <- function(dataframe)
{
 dataframe[is.na(dataframe)] <- 0
 return(dataframe)
}

You will now go to Build - Configure Build Tools and you should end up here:

Click the checkmark for Generate documentation with Roxygen. Doing so will create this popup, which you can close and hit OK. You probably want to rename your function now from hello.R to something relevant. Now comes the moment of truth to build your package. Do this by clicking Build - Clean and Rebuild.

Now you can search for your package, and it should appear:

Click on it and go through the documentation:

There you have it, a useless package, but think of what you can do by packaging your own or your favorite functions, and anyone who inherits your code will thank you.