class: center, middle, title-slide .title[ # Interactive Visualization 2: Building Websites ] .subtitle[ ## JSC 370: Data Science II ] --- <style type="text/css"> .remark-slide-content { font-size: 26px; padding: 20px 80px 20px 80px; } .remark-code, .remark-inline-code { background: #f0f0f0; } .remark-code { font-size: 24px; } .huge .remark-code { /*Change made here*/ font-size: 200% !important; } .tiny .remark-code { /*Change made here*/ font-size: 50% !important; } #<font size="3" color="red">Text here!</font> #<div class="col2"> and </div> #<center>**Here the text is centered. Here are good resources:**</center> # small image right-aligned #<div align="right"><img src="images/Rmd_cheatsheet.png" width="150px"></div> #Small image centered: #<center><img src="images/Rmd_cheatsheet.png" width="150px"></center> </style> ## Interactive visualization: Topics covered **Last week**: - Interactive plots (`plotly`) - Interactive maps (`plotly`, `Leaflet`) - Interactive tables (`DT`) -- <br> **This week**: We will build static websites using R Markdown and GitHub Pages. We will learn how to render text, code, visuals, and interactive visuals (e.g. with **plotly**, **leaflet**, **DT**, etc.) on the website. --- ## Building websites in R Markdown with GitHub -- To understand how websites are built in R Markdown, we first must understand a bit about <span style="background-color: #33FF99">how R Markdown documents are rendered</span> to produce HTML output. It is not essential to understand all the inner workings of this process to be able to create a website. However, it is important to understand which component is responsible for what since this will make it easier to target appropriate help files when you need them! --- ### What does R Markdown require to render files? -- R Markdown combines several different processes together to create documents. In doing so it requires the use of a few essential ingredients (software and packages): -- - R Markdown: A markup language for creating `.Rmd` files that you have used. - **rmarkdown**: An R package for processing and converting `.Rmd` files into a number of different formats. - **knitr**: An R package for transforming a mixture of R code and text in a `.Rmd` file into a `.md` file by executing the code and 'knitting' the results back into the document. - Pandoc: A document converter designed to convert plain text files from one markup language (including `.Rmd`) into many output formats. It is a command line software with no GUI. It comes bundled with R Studio because rmarkdown relies on it for document conversion. .footnote[*A note on formatting*: **word** indicates an R package, while `word` indicates inline code or file name/format. `word()` indicates a function. Software programs (e.g. R Markdown and Pandoc) are not given a special formatting.] --- ## What happens when we render R Markdown files? The basic workflow structure for an R Markdown document is shown below, highlighting the steps (arrows) and the intermediate files that are created before producing the output. <div style="text-align: center;"> <figure> <img style="width: 550px;vertical-align: middle;" hspace="20px" src="https://bookdown.org/yihui/rmarkdown-cookbook/images/workflow.png" alt="rmarkdown rendering process" </figure> <figcaption><b> </b></figcaption> </div> Rendering R Markdown documents with rmarkdown consists of converting `.Rmd` to `.md` with **knitr**, and then `.md` to our desired output with Pandoc. --- ## What happens when we render R Markdown files? The workflow in more detail is as follows: + The `.Rmd` document is written. It is the original format of the document. It contains a combination of YAML (metadata in the header), text, and code chunks. The YAML header specifies document properties and rendering instructions (like `html_document` for HTML output) + The `knit()` function in **knitr** is used to execute all code embedded within the `.Rmd` file, and prepare the code output to be displayed within the output document. **knitr** handles the execution and translation of all code in the file. All these results are converted into the correct markup language and contained within a temporary `.md` file. --- ## What happens when we render R Markdown files? The workflow in more detail is as follows: 3. The `.md` file is processed by Pandoc. It takes any parameters specified within the YAML frontmatter of the document (e.g., `title`, `author`, and `date`) to convert the document to the output format specified in the `output` parameter (in our case: `html_document` for HTML output) 4. The whole process is implemented by R Markdown (the software) via the function from the built-in **rmarkdown** (package): `rmarkdown::render()` Along the way, we add <span style="background-color: #33FF99">structure and style</span>. A wide range of tools helps us in this process. For creating HTML output, some of these include *Cascading Style Sheets (CSS)* for adding style (e.g., fonts, colors, spacing) to Web documents, raw HTML code, and Pandoc templates. --- ## YAML metadata -- YAML = <s>Yet Another Markup Language</s> YAML Ain't Markup Language It is a data-oriented *language structure* used as the input format for diverse software application. It is not a markup language (which includes indicators or "markup" which direct processing) but a *serialization* language. *Serialization* is the process of converting an object into a format that can be transmitted or stored, by converting the object series of bits. This series of bits is then read later to reconstruct the object. --- ## YAML metadata A typical YAML header looks like this, and contains basic metadata about the document and rendering instructions: ```yaml --- title: My R Markdown Website author: Meredith Franklin output: html_document --- ``` The YAML metadata affects the code, content, and the output. It is processed during many stages of the rendering process by **rmarkdown**, **knitr**, and Pandoc: --- ## YAML metadata - The `title` and `author` fields are processed by Pandoc to set the values of template variables. - The `output` field is used by **rmarkdown** to apply the output format function `rmarkdown::html_document()` in the rendering process. For creating a website we will need to pass additional arguments to the format that we are specifying in `output`. -- **We will come back to specify the YAML metadata necessary for setting up a website.** --- ## Beyond Pandoc Note that not all R Markdown documents are eventually compiled through Pandoc. The intermediate `.md` file could be compiled by other Markdown renderers, including: - The **xaringan** package passes the `.md` output to a JavaScript library, which renders the Markdown content in the web browser. All slides for this course have been produced using this package! - The **blogdown** package supports the `.Rmarkdown` document format, which is knitted to `.md`, and this Markdown document is usually rendered to HTML by an external site generator. Using **blogdown** is another way to create a website out of R Markdown (but today we will be focusing on creating websites using **rmarkdown** and Pandoc) --- ## Summary: What happens when we render R Markdown files? -- In short: `rmarkdown::render()` = `knitr::knit()` + Pandoc <br> -- The YAML metadata in the R Markdown file dictates the process and how the output is produced. <br> --- # Website basics The most common components of a web page are HTML, CSS, and JavaScript. HTML is relatively simple to learn, but CSS and JavaScript can be much more complicated, depending on how much you want to learn and what you want to do with them. You don't need to know much of HTML, CSS, or JavaScript to develop a website using R Markdown. If you want to tweak the appearance of your website, you must have some basic knowledge of web development. --- ## HTML basics HTML = Hyper Text Markup Language. HTML is a standard markup language (not programming language) that provides the primary structure of most websites. HTML defines the basic structure of a web page. HTML work on the look of the website without the interactive effects and all. HTML pages are static which means the content cannot be changed. All elements in HTML are represented by tags. Most HTML tags appear in pairs, with an opening tag and a closing tag, and content is placed between the opening and closing tags, e.g., `<span style="background-color: #33FF99">This is highlighted text</span>` --> <span style="background-color: #B9BFFF">This is highlighted text</span>. There are a few exceptions, such as the `<img>` tag, which can be closed by a slash / in the opening tag, e.g., `<img src="foo.png" />`. You can specify attributes of an element in the opening tag using the syntax name=value (a few attributes do not require value). Basically an HTML document consists a `head` section and `body` section. You can specify the metadata and include assets like CSS files in the head section. You can use `View -> Developer -> Source` to see HTML source code. --- ## Helpful HTML Font size and color `<font size="3" color="red">Text here!</font>` Columns `<div class="col2"> and </div>` Centered text `<center>**Here the text is centered. Here are good resources:**</center>` Small image right-aligned `<div align="right"><img src="images/Rmd_cheatsheet.png" width="150px"></div>` Large image centered: `<center><img src="images/Rmd_cheatsheet.png" width="500px"></center>` --- ## CSS basics CSS = Cascading Stylesheets (CSS). It is a markup language used to describe the look and formatting of documents written in HTML. It is responsible for the visual style of your site: - color palettes, - images, - layouts/margins - fonts as well as interactive components like - drop down menus - buttons, and forms --- ## CSS basics There are 3 ways to define styles: - in-line with HTML - placing a style section in your HTML document - define the CSS in an external file that is then referenced as a link in your HTML (most flexible) --- ## JavaScript JavaScript is an advanced programming language (unlike HTML and CSS, which do not contain any programming logic) that makes web pages more interactive and dynamic. JavaScript simply adds dynamic content to websites to make them look good. JavaScript can be embedded inside HTML. An effective way to learn it is through the JavaScript console in the Developer Tools of your web browser because you can interactively type code in the console and execute it, which feels similar to executing R code in the R console (e.g., in RStudio). You may open any web page in your web browser, then open the JavaScript console, and try the code below on any web page: --- ## JavaScript ``` document.body.style.background = 'orange'; ``` Should turn the background orange, unless the page has already defined background colors for certain elements. To effectively use JavaScript, you have to learn both the basic syntax of JavaScript and how to select elements on a page before you can manipulate them. Learn more on the blogdown website to effectively use JavaScript, you have to learn both the basic syntax of JavaScript and how to select elements on a page before you can manipulate them. --- ## Website basics: learning more The best way to learn about what goes into web development: use "Developer Tools", e.g. `View -> Developer` in Google Chrome. Or right click and "inspect". A brief intro to HTML, CSS, and JavaScript is provided in the [blogdown book](https://bookdown.org/yihui/blogdown/website-basics.html) You can also learn more at [w3schools](https://www.w3schools.com/) or course StackOverflow! --- # Building a website using **rmarkdown** --- ## Background: Static vs. dynamic websites A _dynamic site_ relies on a server-side language to do certain computing and sends potentially different content depending on different conditions. A common language is PHP, and a typical example of a dynamic site is a web forum. For example, each user has a profile page, but typically this does not mean the server has stored a different HTML profile page for every single user. Instead, the server will fetch the user data from a database, and render the profile page dynamically. A _static site_ consists of static files such as HTML, CSS, JavaScript, images, etc., and the web server sends exactly the same content to the web browser no matter who visits the web pages. There is no dynamic computing on the server when a page is requested. *It is just one folder of static files.* --- ## Creating websites through **rmarkdown** **rmarkdown** has a built-in *static* site generator, which we will be using. It uses Bootstrap CSS styles and themes (which you can choose from). -- There are many existing static site generators, including Hugo, Jekyll, and Hexo, etc. These provide many site themes, templates, and features, but are more complex than **rmarkdown**'s built-in generator. -- **rmarkdown**'s site generator is a good option if: - You are familiar with generating single-page HTML output from R Markdown - You want to build a simple website with a few pages - It suffices to use a flat directory of `.Rmd` files - You don't require features such as forums or RSS feeds --- ## Creating websites through **rmarkdown** We can render collections of R Markdown documents as a website using the `rmarkdown::render_site()` function -- The RStudio IDE (version 1.0 or higher) also includes integrated support for developing R Markdown websites through the `Build` toolbar. These make use of an RStudio Project tied to your website's directory. -- In lab, we will use the RStudio IDE and command line to build our websites, and deploy them on GitHub pages. We will focus on both local and remote setup. -- The focus of the remaining lecture component will be to overview the pieces needed to create a website, and provide some background on different features to be aware of. --- # Overview There are two main steps for creating a personal website that will be hosted on GitHub: - Create website through local setup - Deploy website through GitHub setup --- ## Overview: Local Setup 1. Create a project directory and an R Project file (`.Rproj`) 1. Create a `_site.yml` and `index.Rmd` file in your new directory 1. Add additional page content if desired through other `.Rmd` files 1. Edit these files to create content and manage layout (and knit to view) 1. Add a style sheet (CSS) if desired 1. Build website - Build tab > Build Website or - in the console: `rmarkdown::render_site()` This creates the output: `index.html` -- Let's break this down, foucusing on the essential content of the website. --- ## Essential elements The minimum requirement for any R Markdown website is that it have an `index.Rmd` file as well as a `_site.yml` file. To start with, let's walk through a very simple example, a website that includes two pages (`Home` and `About`) and a navigation bar to switch between them. --- ## A simple example First, we need a configuration file `_site.yml`: ```yaml name: "my-website" navbar: title: "My Website" left: - text: "Home" href: index.html - text: "About" href: about.html ``` --- ## A simple example (cont'd) Then two Rmd files, `index.Rmd`: ```markdown --- title: "My Website" --- Hello, Website! ``` and `about.Rmd`: ```markdown --- title: "About This Website" --- More about this website. ``` --- # Common elements Now let's talk in a bit more detail about the essential `_site.yml`, the `index.Rmd`, and other non-essential common elements. Typically when creating a website, there are various common elements you want to include on all pages (e.g., output options, CSS styles, header and footer elements, etc.) --- ## Common elements: `_site.yml` A more detailed `_site.yml` could look like this: .tiny[ ```yaml name: "my-website" output_dir: "." navbar: title: "My Website" left: - icon: fa-home href: index.html - text: "About" href: about.html right: - text: "External website" - href: www.google.com output: html_document: theme: cosmo highlight: textmate include: after_body: footer.html css: styles.css ``` ] --- ## Common elements: `_site.yml` - The `name` field provides a suggested URL path for your website when it is published (by default this is just the name of the directory containing the site). -- - The `output_dir` field indicates which directory to copy site content into (`"_site"` is the default if none is specified). It can be `"."` to keep all content within the root website directory alongside the source code. -- - The `output` element within our `_site.yml` file defines shared output options for all R Markdown documents within a site. Note that individual documents can also include their own `output` options, which will be merged with the common options at render time. -- - As part of our common output options, we have specified an HTML footer (via the `include: after-body:` option) and a CSS stylesheet. You can also include HTML before the body or in the document's `<head>` --- ## Common elements: `_site.yml` - In addition to whatever common options you define in the `_site.yml`, there are two output options that are automatically set when rendering a site: - The `self_contained` option is set `FALSE` - The `lib_dir` option is set to `site_libs`. These options are set so that dependent files (e.g. HTML widget libraries) are shared across all documents within the site rather than redundantly embedded within each document. --- ## `_site.yml`: `navbar` The `navbar` element of `_site.yml` can be used to define a common navigation bar for your website. You can include internal and external links on the navigation bar as well as drop-down menus for sites with a large number of pages. Some capabilities of navigation bars: - You can use the `type` field to choose between the `default` and `inverse` navigation bar styles (each theme includes distinct colors for "default" and "inverse" navigation bars). -- - You can align navigational items either to the `left` or to the `right`. -- - You can include both internal and external links on the navigation bar. --- ## `_site.yml`: `navbar` - You can use icons on the navigation bar. Icons from three different icon sets are available. - [Font Awesome](https://fontawesome.com/icons) - [Ionicons](http://ionicons.com/) - [Bootstrap Glyphicons](https://getbootstrap.com/docs/3.3/components/#glyphicons) When referring to an icon, you should use its full name including the icon set prefix (e.g., `fa-github`, `ion-social-twitter`, and `glyphicon-time`). --- ## Common elements: other - Include a footer: `footer.html`: ```html <p>Copyright &copy; 2016 Skynet, Inc. All rights reserved.</p> ``` - Style sheets: `styles.css` ```css blockquote { font-style: italic } ``` --- ## Rendering and building the site As you work on the individual pages of your website, you can render them using the `Knit` button just as you do with conventional standalone R Markdown documents <img src="img/site-page.png" width="30%" style="display: block; margin: auto;" /> Knitting an individual page will only render and preview that page, not the other pages in the website. To render all of the pages in the website, you use the `Build` pane, which calls `rmarkdown::render_site()` to build and then preview the entire site <div class="figure" style="text-align: center"> <img src="img/site-build.png" alt="Build an entire website in RStudio." width="25%" /> <p class="caption">Build an entire website in RStudio.</p> </div> --- ## Rendering and building the site (cont'd) RStudio supports "live preview" of changes that you make to supporting files within your website (e.g., CSS, JavaScript, `.Rmd` partials, R scripts, and YAML config files). Changes to CSS and JavaScript files always result in a refresh of the currently active page preview. Changes to other files (e.g., shared scripts and configuration files) trigger a rebuild of the active page (this behavior can be disabled via the options dialog available from the `Build` pane). Note that only the active page is rebuilt, so once you are happy with the results of rendering you should make sure to rebuild the entire site from the `Build` pane to ensure that all pages inherit your changes. In other words, you need to re-build the website to integrate any new changes to one page. --- ### Rendering and building the site: command line Or from command line: you can call the `render_site()` function directly from within the website directory. Pass no arguments to render the entire site or a single file in order to render just that file: ```r # render the entire site rmarkdown::render_site() # render a single file only rmarkdown::render_site("about.Rmd") ``` --- ### Rendering and building the site: command line If you execute the `rmarkdown::render_site()` function from within the directory containing the website, the following will occur: - All of the `*.Rmd` and `*.md` files in the root website directory will be rendered into HTML. Note, however, that Markdown files beginning with `_` are not rendered (this is a convention to designate files that are to be included by top level Rmd documents as child documents). - The generated HTML files and any supporting files (e.g., CSS and JavaScript) are copied into an output directory (`_site` by default). - The HTML files within the `_site` directory are now ready to deploy as a standalone static website. **Note**: The `include` and `exclude` fields of `_site.yml` can be used to override this default behavior --- # Helpful features --- ## R Markdown website themes R Markdown makes styling easy for you. The HTML output of R Markdown includes the Bootstrap framework. Bootstrap has multiple themes we can choose from. We can change the website’s theme in _site.yml. Explore themes [here](https://www.datadreaming.org/post/r-markdown-theme-gallery/#:~:text=There%20are%2012%20additional%20themes,your%20theme%20from%20the%20default%20.) Valid themes include “default”, “cerulean”, “journal”, “flatly”, “readable”, “spacelab”, “united”, “cosmo”, “lumen”, “paper”, “sandstone”, “simplex”, and “yeti”. --- ## R scripts If you have R code that you would like to share across multiple R Markdown documents within your site, you can create an R script (e.g., `utils.R`) and source it within your Rmd files. For example: ```markdown ```{r} source("utils.R") ``` --- ## Adding interactive content R Markdown includes many facilities for generation of HTML content from R objects, including: - The conversion of standard R output types (e.g., **ggplot2** objects) within code chunks done automatically by **knitr** - A variety of ways to generate HTML tables, including the `knitr::kable()` function and other packages such as **kableExtra** - A large number of available HTML widgets (e.g., **plotly** objects) that provide rich JavaScript data visualizations. As a result, for many R Markdown websites _you will not need to worry about generating HTML output at all_ (since it is created automatically). --- ## Saving interactive plots as HTML widgets If you are having issues with embedding interactive plots, you can use the package **widgetframe** to save HTML files via an HTML `iframe`. This is convenient not only for re-using a widget in various parent documents, but also for preventing any JavaScript and CSS in the parent document from negatively impacting how the widget renders The **widgetframe** package automates the saving of widgetframe packages into <iframes> and has options for controling where, how, and if external dependencies are stored on the file system when using it inside a knitr/rmarkdown document. **widgetframe** is designed to be used in `.Rmd` documents which will eventually be knitted to an HTML or a derived format. Use the default options and embed files like this: --- ## Saving interactive plots as HTML widgets ```markdown ```{r} library(widgetframe) test.widget <- plot_ly() widgetframe::frameWidget(test.widget, width = '75%') ``` **widgetframe** will take care of embedding the supporting HTML widget libraries in a folder together. --- ## Adding dynamic content To add something dynamic and always changing with external input (like a comment box), you can incorporate an outside commenting system like [Disqus](https://gohugo.io/content-management/comments/). Disqus is a third-party service that provides comment and community capabilities to websites via JavaScript. --- ## knitr caching If your website is time consuming to render, you may want to enable **knitr**'s caching during the development of the site, so that you can more rapidly preview. To enable caching for an individual chunk, just add the `cache = TRUE` chunk option: ````markdown ```{r, cache = TRUE} data <- longComputation() ``` ```` To enable caching for an entire document, add `cache = TRUE` to the global chunk option defaults: ````markdown ```{r setup, include=FALSE} knitr::opts_chunk$set(cache = TRUE) ``` ```` Note that when caching is enabled for an Rmd document, its `*_files` directory will be copied rather than moved to the `_site` directory (since the cache requires references to generated figures in the `*_files` directory). --- ## Cleaning up files To clean up all of the files generated via `render_site()`, you can call the `clean_site()` function, which will remove all files generated by rendering your site's Markdown documents, including **knitr**'s `*_cache` directories. You can specify the `preview = FALSE` option to just list the files to be removed rather than actually removing them: ```r # list which files will be removed rmarkdown::clean_site(preview = TRUE) # actually remove the files rmarkdown::clean_site() ``` --- ## How to help people find your site Search Engine Optimization is the art of making a website easy for search engines like Google to understand. There are multiple books and moreover companies devoted to improving SEO. A few key points: - The title that you select for each page and post is a very important signal to Google and other search engines telling them what that page is about. - Description tags are also critical. In HTML documents, description tags are one way to provide metadata about the page. You can add a description to your YAML header like: ``` description: "A brief description of this page that helps SEO find it!."; ``` - URL structure matters. A good place to learn more is the Google Search Engine Optimization Starter Guide (http://bit.ly/google-seo-starter) --- # Deploying website Your static website is basically a folder containing static files. All site content (generated documents and supporting files) are copied into the `_site` directory, so deployment is simply a matter of moving that directory to the appropriate directory of a web server, and your website will be up and running shortly. The key question is which web server you want to use. We will focus on hosting websites through GitHub pages. Hosting websites on GitHub pages is free. We will see how to do this in the lab. There are other free sites for website hosting, and another popular and free choice is [Netlify](https://www.netlify.com/). --- ## Deploying website through GitHub pages The workflow for deploying to GitHub pages is as follows: 1. Create project on GitHub 1. Initialize project on Git 1. Push project files to the GitHub repository for your project 1. Deploy the website by enabling GitHub pages for the repository -- We will overview this in more detail during the lab. --- # More advanced website creation options with .Rmd files **blogdown** package, built on the static website generator Hugo: provides support for developing a website from `.Rmd` files based on Hugo Benefits of **blogdown**/Hugo combination over **rmarkdown** built in generator: - Hugo is a general-purpose site generator that is highly customizable - Supports more features, e.g. RSS feeds, metadata especially common in blogs such as categories and tags - faster to render content - extended syntax, which means it is highly suitable for technical writing - Many [beautiful themes](https://themes.gohugo.io/) available <div style="text-align: center;"> <a href="https://themes.gohugo.io/"> <figure> <img style="width: 400px;vertical-align: middle;" hspace="20px" src="img/hugo-themes.png" alt="Hugo themes" </figure> <figcaption><b>Window into the themes available from Hugo's website generator</b></figcaption> </div> --- ## Website with Hugo and **blogdown** Developing a website with Hugo and **blogdown** is not that much more complicated. It uses the following file and folder structure: - `config.toml` - `content/` - `static/` - `themes/` - `layouts/` You can read more about this in the [**blogdown** book, Chapter 2](https://bookdown.org/yihui/blogdown/hugo.html) --- ## Website with Hugo and **blogdown** Some example websites using Hugo and **blogdown**: - [Malcolm Barrett](https://malco.io/) - [Abigail Horn](https://abigailhorn.netlify.app/) - [Andreas Handel](https://www.andreashandel.com/) - See Andreas' [tutorial](https://www.andreashandel.com/posts/blogdown-website-1/) on creating a Hugo Academic theme website in **blogdown** --- # Resources #### Website development using R Markdown Useful references for creating websites can be found here: - [R Markdown reference guide](https://bookdown.org/yihui/rmarkdown/) - [R Markdown basic website themes](https://www.datadreaming.org/post/r-markdown-theme-gallery/#:~:text=There%20are%2012%20additional%20themes,your%20theme%20from%20the%20default%20.) Tutorials on creating a website using R Markdown - [Creating websites in R](https://www.emilyzabor.com/tutorials/rmarkdown_websites_tutorial.html), Emily C. Zabor - [Nick Strayer & Lucy D'Agostino McGowan](https://livefreeordichotomize.com/2017/08/08/how-to-make-an-rmarkdown-website/) --- # More Resources #### More advanced website development using R Markdown - For more advanced website creation using **blogdown** and the website generator Hugo see [Creating websites with R Markdown](https://bookdown.org/yihui/blogdown/). - [Appendix B](https://bookdown.org/yihui/blogdown/website-basics.html#website-basics) of the **blogdown** book presents basic information about websites, such as HTML, CSS, and JavaScript - A good resource for further information on customizing CSS and JavaScript is [w3schools](https://www.w3schools.com/w3css/defaulT.asp) --- # More Resources #### Making interactive plots `shiny` and dashboards and hosting on websites - [The `Shiny` Website](http://shiny.rstudio.com) - [R Markdown: The Definitive Guide, Chapter 5: Dashboards (Layout, Components, Shiny)](https://bookdown.org/yihui/rmarkdown/dashboards.html) --- # References This lecture is based on [Chapter 10.5: Websites in rmarkdown’s site generator](https://bookdown.org/yihui/rmarkdown/rmarkdown-site.html) from the book [R Markdown: The Definitive Guide](https://bookdown.org/yihui/rmarkdown/), by Yihui Xie, J. J. Allaire, Garrett Grolemund It pulls also from the tutorial [Creating websites in R](https://www.emilyzabor.com/tutorials/rmarkdown_websites_tutorial.html) by Emily C. Zabor