ggvis and shiny

server.R

library(shiny)
library(ggvis)

data(diamonds, package = "ggplot2")

shinyServer( function(input, output, session) {

  
  hist_standard <- reactive({
        
    ggvis(diamonds, props(x = ~table)) +
      layer_histogram(binwidth = 1)
    
  })
  
  hist_stacked <- reactive({
        
    ggvis(diamonds, 
          by_group(cut), 
          props(x = ~table, fill = ~cut),
          transform_bin(binwidth = 1)) +
    layer(
      props(x = ~xmin__, x2 = ~xmax__, y = ~count__, fillOpacity := 0.6),
      layer(
        transform_stack(),
        mark_rect(props(y = ~ymax__, y2 = ~ymin__))
      )
    )
  
  })
  
  observe_ggvis(hist_standard, "hist_standard", session)
  observe_ggvis(hist_stacked, "hist_stacked", session)
  
})

ui.R

library(shiny)

shinyUI( fluidPage(
  
  titlePanel("Histogram test"),
  
  sidebarLayout( 
    
    sidebarPanel(
      helpText(
        p("The goal is to get a ggvis plot to work within shiny."),
        p("Using the diamonds dataset, a couple of ggvis plots are made:"),
        tags$ol(
          tags$li("a \"standard\" histogram using", code("layer_histogram()")),
          tags$li("a \"stacked\" histogram using techniques outlined in the ggvis",
                  a("histogram demo.", 
                    href = "https://github.com/rstudio/ggvis/blob/master/demo/histogram.r") )
        ),
        p("The standard histogram works interactively and in shiny.",
          "The stacked histogram works interactively, but not in shiny."),
        p("I would not be surprised if this has to do with non-standard evaluation within a reactive",
          "environment, and my inability to navigate between the two."),
        p("As a next step, I would be like to be able to use a", code("selectInput()"),
          "to allow the user to see how the distributions change according to cut, color, depth, etc.",
          "First, I need to be able to get the stacked historgram to work.")
      )
    ),
    
    mainPanel(
      ggvis_output("hist_standard"),
      ggvis_output("hist_stacked")
    )
    
  )
  
))