Book Image

Web Application Development with R Using Shiny - Third Edition

By : Chris Beeley, Shitalkumar R. Sukhdeve
Book Image

Web Application Development with R Using Shiny - Third Edition

By: Chris Beeley, Shitalkumar R. Sukhdeve

Overview of this book

Web Application Development with R Using Shiny helps you become familiar with the complete R Shiny package. The book starts with a quick overview of R and its fundamentals, followed by an exploration of the fundamentals of Shiny and some of the things that it can help you do. You’ll learn about the wide range of widgets and functions within Shiny and how they fit together to make an attractive and easy to use application. Once you have understood the basics, you'll move on to studying more advanced UI features, including how to style apps in detail using the Bootstrap framework or and Shiny's inbuilt layout functions. You'll learn about enhancing Shiny with JavaScript, ranging from adding simple interactivity with JavaScript right through to using JavaScript to enhance the reactivity between your app and the UI. You'll learn more advanced Shiny features of Shiny, such as uploading and downloading data and reports, as well as how to interact with tables and link reactive outputs. Lastly, you'll learn how to deploy Shiny applications over the internet, as well as and how to handle storage and data persistence within Shiny applications, including the use of relational databases. By the end of this book, you'll be ready to create responsive, interactive web applications using the complete R (v 3.4) Shiny (1.1.0) suite.
Table of Contents (11 chapters)

Reactivity in RShiny

RShiny uses a reactive programming coding pattern, which makes applications responsive. In reactive programming, there are basically three elements:

  • Reactive Source
  • Reactive Endpoint
  • Reactive Conductor

The combination of these elements is what makes a Shiny app more responsive. Let's have a look in more detail at how they work:

  • Reactive Source: The reactive source is the input objecting the Shiny app. It takes the input from the user and keeps it in the Input object. The Input object is associated with any UI element, with which the user interacts and provides input. It can be an input box, an action button, an interactive table or plot, or any other UI component. For example, if we take input from a text box named txtbox in the UI code, we can say that input$txtbox is the reactive source.
  • Reactive Endpoint: The reactive endpoint is the output object...