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  3. Case Studies: Building Web Applications with Shiny in R
  • 1

    Shiny review

    Free

    In the first chapter, you'll review the essentials of Shiny development. You'll get reintroduced to the basic structure of a Shiny application, as well as some core Shiny concepts such as inputs, outputs, and reactivity. Completing this chapter will help refresh your Shiny knowledge and ensure you have the required skills to develop Shiny apps for real-life scenarios.

  • 2

    Make the perfect plot using Shiny

    Imagine you're preparing a figure for a manuscript using R. You spend a lot of time recreating the same plot over and over again by rerunning the same code but changing small parameters each time. The size of the points, the color of the points, the plot title, the data shown on the plot—these criteria all have to be just right before publishing the figure. To save you from the hassle of rerunning the code many times, you will learn how to create a Shiny app to make a customizable plot.

  • 3

    Explore a dataset interactively with Shiny

    Let’s say your supervisor is impressed by the plot you created with Shiny and now wants to get familiar with the dataset you used in the plot. They don't want to simply have a raw data file, they want an interactive environment where they can view the data, filter it, and download it. This chapter will guide you in creating such an application—a Shiny app for exploring the Gapminder dataset.

  • 4

    Create your own word cloud in Shiny

    Your friend really likes word clouds and has written an R function to generate them. They want to share this function with all their friends, but not all of them know how to use R. You offer to help by building a Shiny app that uses their function to let people create their own word clouds. This will allow all their friends—even the ones who are unfamiliar with R—to generate word clouds using a point-and-click interface. This chapter will guide you through the steps required to build this app.

Initializing

Exercise

Choose the data source (server)

When working with radio buttons, sometimes you need to use conditional logic (if-else statements) when accessing the radio button's value in the server. This is necessary when different actions are performed depending on the exact choice, and the chosen value needs to be inspected before deciding how to proceed.

For example, with the radio buttons that select a data source, different code will need to run depending on which choice is selected.

Your next task is to use the appropriate data source in the word cloud function, according to what radio button the user chooses.

Instructions

100 XP
  • Define a reactive variable named data_source to hold the data that will be used for the word cloud (line 28).
  • If the "book" option ("Art of War") is selected, assign the artofwar book as the data source. If the "own" option ("Use your own words") is selected, assign the textarea's value as the data source. If the "file" option ("Upload a file") is selected, assign the text from a user-submitted file as the data source (lines 33 through 36).
  • Use the data_source() reactive variable as the data argument to the word cloud function (line 51).