Shiny not displaying my ggplot as I'd expect

Question

What\'s keeping my little Shiny app from displaying my ggplot? When I replace the code in renderPlot() with an example using the base plot function it comes together. I\'m

Answer 1

Your code needed a couple of changes to get ggplot to render. As the comments above state, print(ggplot) was needed. But also, aes inside ggplot can't deal with subsetting.

So you subset your city of interest in a separate reactive, and call that from ggplot.

city.df <- reactive({
    subset(finalDat, City == input$city)
  })  

  output$CAFRplot <- renderPlot({
    city <- city.df()

    print(ggplot(city, aes(x = Year, y=Value)) + geom_point())

The full server.R (this works)

library(shiny)
library(ggplot2)

cities <- c("Anchorage","Fairbanks","Juenau","Wasilla","Homer")
years <- 2003:2013
Table <- "Capital Assets"
Account <- c("Land", "Art", "Buildings", "Equipment")
dat <- data.frame(City = sort(rep(cities, length(years))), Year = rep(years,length(cities)), Table)
sampleDat <- rbind(data.frame(dat,Acount = Account[1]), data.frame(dat, Acount = Account[2]), data.frame(dat, Acount = Account[3]), data.frame(dat, Acount = Account[4]))
finalDat <- data.frame(sampleDat, Value = runif(length(sampleDat[,1]), 1000,10000) )

shinyServer(function(input, output) {

  formulaText <- reactive({
    paste(input$city)
  })

  output$caption <- renderText({
    formulaText()
  })

  city.df <- reactive({
    subset(finalDat, City == input$city)
  })  

  output$CAFRplot <- renderPlot({
    city <- city.df()
    ## this one isn't working.
#    print(ggplot(finalDat, aes(x = finalDat[which(finalDat$City == input$city),2], 
#                         y = finalDat[which(finalDat$City == input$city),5])) +  geom_point())

    print(ggplot(city, aes(x = Year, y=Value)) + geom_point())

    ## this one is working
    #plot(finalDat[which(finalDat$City == input$city),2], y = finalDat[which(finalDat$City == input$city),5])


  })
})