R Package Development: From Idea to CRAN

Complete tutorial for creating your first R package

R
packages
development
tutorial
Step-by-step guide to developing, documenting, and submitting an R package to CRAN.

1 Learning Objectives

By the end of this tutorial, you will: - Set up a proper R package development environment - Create package structure and documentation - Write and test package functions - Prepare for CRAN submission

2 Prerequisites

  • Basic R programming knowledge
  • RStudio installed
  • Git familiarity (helpful but not required)

3 Step 1: Development Environment Setup

First, install the essential packages for R development:

install.packages(c("devtools", "usethis", "roxygen2", "testthat"))

Configure your development environment:

library(usethis)
use_git_config(user.name = "Your Name", user.email = "your.email@example.com")

4 Step 2: Create Package Structure

Create a new package:

create_package("~/path/to/mypackage")

This creates the standard package directory structure: - R/ - Your R functions - man/ - Documentation files (auto-generated) - DESCRIPTION - Package metadata - NAMESPACE - Exported functions (auto-generated)

5 Step 3: Write Your First Function

Create a new R file in the R/ directory:

#' Add two numbers together
#'
#' This function takes two numeric inputs and returns their sum.
#'
#' @param x A numeric value
#' @param y A numeric value
#' @return The sum of x and y
#' @export
#' @examples
#' add_numbers(2, 3)
#' add_numbers(10, -5)
add_numbers <- function(x, y) {
  if (!is.numeric(x) || !is.numeric(y)) {
    stop("Both inputs must be numeric")
  }
  x + y
}

6 Step 4: Generate Documentation

Use roxygen2 to generate documentation:

devtools::document()

This creates help files in the man/ directory and updates your NAMESPACE.

7 Step 5: Testing

Create unit tests to ensure your functions work correctly:

usethis::use_testthat()
usethis::use_test("add_numbers")

Write tests in tests/testthat/test-add_numbers.R:

test_that("add_numbers works correctly", {
  expect_equal(add_numbers(2, 3), 5)
  expect_equal(add_numbers(-1, 1), 0)
  expect_error(add_numbers("a", 1))
})

Run tests:

devtools::test()

8 Step 6: Package Checks

Before submitting to CRAN, run comprehensive checks:

devtools::check()

This runs R CMD check and identifies potential issues.

9 Step 7: Preparing for CRAN

Update your DESCRIPTION file with proper metadata:

Package: mypackage
Title: What the Package Does (One Line, Title Case)
Version: 0.1.0
Authors@R: 
    person("First", "Last", , "first.last@example.com", role = c("aut", "cre"))
Description: What the package does (one paragraph).
License: MIT + file LICENSE
Encoding: UTF-8
Roxygen: list(markdown = TRUE)
RoxygenNote: 7.2.3
Suggests: 
    testthat (>= 3.0.0)
Config/testthat/edition: 3

10 Next Steps

  • Add more functions and documentation
  • Create vignettes for complex workflows
  • Set up continuous integration
  • Submit to CRAN when ready

11 Resources