Write Vignette

Create long-form documentation vignettes for R packages.

When to Use

• •Adding a "Getting Started" tutorial for a package
• •Documenting complex workflows that span multiple functions
• •Creating domain-specific guides (e.g., statistical methodology)
• •CRAN submission requires user-facing documentation beyond function help

Inputs

• •Required: R package with functions to document
• •Required: Vignette title and topic
• •Optional: Format (R Markdown or Quarto, default: R Markdown)
• •Optional: Whether the vignette needs external data or APIs

Procedure

Step 1: Create Vignette File

usethis::use_vignette("getting-started", title = "Getting Started with packagename")

Expected: vignettes/getting-started.Rmd created. knitr and rmarkdown added to Suggests.

Step 2: Write Vignette Content

---
title: "Getting Started with packagename"
output: rmarkdown::html_vignette
vignette: >
  %\VignetteIndexEntry{Getting Started with packagename}
  %\VignetteEngine{knitr::rmarkdown}
  %\VignetteEncoding{UTF-8}
---

## Introduction

Brief overview of what the package does and who it's for.

## Installation

```r
install.packages("packagename")
library(packagename)

Basic Usage

Walk through the primary workflow:

# Load example data
data <- example_data()

# Process
result <- main_function(data, option = "default")

# Inspect
summary(result)

Advanced Features

Cover optional or advanced functionality.

Conclusion

Summarize and point to other vignettes or resources.

### Step 3: Configure Code Chunks

Use chunk options for different purposes:

```r
# Standard evaluated chunk
{r example-basic}
result <- compute_something(1:10)
result

# Show code but don't run (for illustrative purposes)
{r api-example, eval=FALSE}
connect_to_api(key = "your_key_here")

# Run but hide code (show only output)
{r hidden-setup, echo=FALSE}
library(packagename)

# Set global options
{r setup, include=FALSE}
knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>",
  fig.width = 7,
  fig.height = 5
)

Step 4: Handle External Dependencies

For vignettes that need network access or optional packages:

{r check-available, include=FALSE}
has_suggested <- requireNamespace("optionalpkg", quietly = TRUE)

{r use-suggested, eval=has_suggested}
optionalpkg::special_function()

For long-running computations, pre-compute and save results:

# Save pre-computed results to vignettes/
saveRDS(expensive_result, "vignettes/precomputed.rds")

# Load in vignette
{r load-precomputed}
result <- readRDS("precomputed.rds")

Step 5: Build and Test Vignette

# Build single vignette
devtools::build_vignettes()

# Build and check (catches vignette issues)
devtools::check()

Expected: Vignette builds without errors. HTML output is readable.

On failure:

• •Missing pandoc: Set RSTUDIO_PANDOC in .Renviron
• •Package not installed: Run devtools::install() first
• •Missing Suggests: Install packages listed in DESCRIPTION Suggests

Step 6: Verify in Package Check

devtools::check()

Vignette-related checks: builds correctly, doesn't take too long, no errors.

Validation

• • Vignette builds without errors via devtools::build_vignettes()
• • All code chunks execute correctly
• • VignetteIndexEntry matches the title
• • devtools::check() passes with no vignette warnings
• • Vignette appears in pkgdown site articles (if applicable)
• • Build time is reasonable (< 60 seconds for CRAN)

Common Pitfalls

• •VignetteIndexEntry mismatch: The index entry in YAML must match what you want users to see in vignette(package = "pkg")
• •Missing vignette YAML block: All three %\Vignette* lines are required
• •Vignette too slow for CRAN: Pre-compute results or use eval=FALSE for expensive operations
• •Pandoc not found: Ensure RSTUDIO_PANDOC environment variable is set
• •Self-referencing package: Use library(packagename) not devtools::load_all() in vignettes

Related Skills

• •write-roxygen-docs - function-level docs complement vignette tutorials
• •build-pkgdown-site - vignettes appear as articles on pkgdown site
• •submit-to-cran - CRAN has specific vignette requirements
• •create-quarto-report - Quarto as an alternative to R Markdown vignettes