Change the word cloud parameters

Recall that create_wordcloud() has two optional arguments: num_words, which is an integer specifying the maximum number of words to draw, and background, which specifies the background color of the image.

Right now, the Shiny app simply outputs a word cloud with the exact same parameters all the time. Since the word cloud generating function accepts these two parameters, it would be wasteful not to use them. The parameters should be adjustable by the user using Shiny inputs.

Your task is to add two inputs to the Shiny app, and use the values from these inputs as the num_words and background parameters of the word cloud.

This exercise is part of the course

Case Studies: Building Web Applications with Shiny in R

Exercise instructions

All the required packages, including colourpicker, have been loaded to your workspace. Specifically:

Add a numeric input with an ID of "num", a default value of 100, and minimum value of 5.
Add a color input (from the colourpicker package) with an ID of "col", a label of "Background color", and a default color of "white".
Use the values from the two inputs to set the parameters of create_wordcloud() (line 16).

Hands-on interactive exercise

Have a go at this exercise by completing this sample code.

ui <- fluidPage(
  h1("Word Cloud"),
  # Add a numeric input for the number of words
  ___(inputId = ___, label = "Maximum number of words",
      value = ___, min = ___),
  # Add a color input for the background color
  ___(___),
  wordcloud2Output("cloud")
)

server <- function(input, output) {
  output$cloud <- renderWordcloud2({
    # Use the values from the two inputs as
    # parameters to the word cloud
    create_wordcloud(artofwar,
                     num_words = ___, background = ___)
  })
}

shinyApp(ui = ui, server = server)

Edit and Run Code

This exercise is part of the course

Case Studies: Building Web Applications with Shiny in R

IntermediateSkill Level

4.8+

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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.

Exercise 1: Introduction Exercise 2: Simple text Exercise 3: Formatted text Exercise 4: Adding structure to your app Exercise 5: Inputs and outputs Exercise 6: Adding inputs Exercise 7: Adding placeholders for outputs Exercise 8: Constructing output objects Exercise 9: Reactivity 101 Exercise 10: Reactivity: simple reactive variable Exercise 11: Reactivity: composed reactive variable Exercise 12: Reactive contexts

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.

Exercise 1: Make the perfect plot using Shiny Exercise 2: Explore the Gapminder data Exercise 3: More exploration of the Gapminder data Exercise 4: Adding simple inputs to modify a plot Exercise 5: Add a plot title: text input Exercise 6: Change the point size: numeric input Exercise 7: Fit a smooth curve: checkbox input Exercise 8: More input types Exercise 9: Add colours to your plot: radio buttons Exercise 10: Add a continent selector: select input Exercise 11: Add a year filter: numeric slider input Exercise 12: Advanced features to improve your plot Exercise 13: Add colours to your plot: color input Exercise 14: Making your plot larger Exercise 15: Make your plot interactive

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.

Exercise 1: Explore a dataset with Shiny Exercise 2: See the data in a table Exercise 3: Filter by life expectancy Exercise 4: Select a continent to view Exercise 5: Allow "All" continents to be viewed Exercise 6: More ways to view data: plot and download Exercise 7: Plot the data Exercise 8: Download the filtered data Exercise 9: Reactive variables Exercise 10: Reactive variables reduce code duplication Exercise 11: More benefits of reactive variables Exercise 12: Visual enhancements Exercise 13: Make the table interactive Exercise 14: Place different outputs on different tabs Exercise 15: Add CSS to modify the look of the app

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.

Exercise 1: Word clouds in Shiny Exercise 2: Word cloud Shiny app Exercise 3: Change the word cloud parameters

Current Exercise

Exercise 4: Add a layout Exercise 5: Adding word sources Exercise 6: Use your own words Exercise 7: Upload a text file (ui)Exercise 8: Upload a text file (server)Exercise 9: Combining all the word sources Exercise 10: Choose the data source (ui)Exercise 11: Choose the data source (server)Exercise 12: Conditionally show or hide required inputs Exercise 13: Fine tune the reactivity Exercise 14: Don't continuously create new word clouds Exercise 15: Reactivity: effects of isolation Exercise 16: Create a new word cloud on demand Exercise 17: Wrap-up: Go and make your own apps!