Building my first Shiny application with ggplot

In trying to get a grip on the newly released Shiny library for R I simply rewrote the example from the tutorial to work with ggplot. The code is taken from the Shiny Tutorial.

I did not make any changes to ui.R provided in the tutorial. The rewritten server.R is below.

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5 thoughts on “Building my first Shiny application with ggplot”

  1. Thanks for sharing! small changes were made to the syntax apparently, this variant worked:

    library("shiny")
    library("datasets")
    library("ggplot2")

    # We tweak the "am" field to have nicer factor labels. Since this doesn't
    # rely on any user inputs we can do this once at startup and then use the
    # value throughout the lifetime of the application
    mpgData <- mtcars
    mpgData$am <- factor(mpgData$am, labels = c("Automatic", "Manual"))

    # Define server logic required to plot various variables against mpg
    shinyServer(function(input, output) {

    # Compute the forumla text in a reactive expression since it is
    # shared by the output$caption and output$mpgPlot expressions
    formulaText <- reactive({
    paste("mpg ~", input$variable)
    })

    # Return the formula text for printing as a caption
    output$caption <- renderText({
    formulaText()
    })

    # Generate a plot of the requested variable against mpg and only
    # include outliers if requested
    # ggplot version
    output$mpgPlot <- renderPlot({

    # check for the input variable
    if (input$variable == "am") {
    # am
    mpgData <- data.frame(mpg = mtcars$mpg, var = factor(mtcars[[input$variable]], labels = c("Automatic", "Manual")))
    }
    else {
    # cyl and gear
    mpgData <- data.frame(mpg = mtcars$mpg, var = factor(mtcars[[input$variable]]))
    }

    p <- ggplot(mpgData, aes(var, mpg)) +
    geom_boxplot(outlier.size = ifelse(input$outliers, 2, NA)) +
    xlab(input$variable)
    print(p)

    })
    })

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