README.md

I moved the inclusion of the theme url outside of renderChart2, directly into ui.R. The reason for this is that afterScript is only included in the static template for charts. The shiny version only outputs the chart related HTML and currently does not include the contents of afterScript. You could consider this a bug in the implementation of rCharts and I hope to fix it in future versions.

server.R

require(shiny)
require(rCharts)

shinyServer(function(input, output) {

  
  output$plot <- renderChart2({
    
    data(mtcars)
    p <- hPlot(mpg ~ hp, data = mtcars, type = 'scatter', group = input$g_variable)
    p$set(width = "100%", height= "100%")
    
    return(p)
  })
})

ui.R

require(shiny)
require(rCharts)

theme <- 'gray.js'
theme_url <-  sprintf('http://rawgithub.com/highslide-software/highcharts.com/master/js/themes/%s', theme)

shinyUI(fluidPage(
  tags$head(
    tags$link(rel = "stylesheet", type = "text/css", href = "http://bootswatch.com/superhero/bootstrap.min.css")
  ),
  titlePanel("Migrations Analysis"),
  sidebarLayout(
    sidebarPanel(
      radioButtons(
        inputId = "g_variable",
        label = "Group by",
        choices = list( "Cyl" = "cyl",
                        "VS" = "vs",
                        "AM" = "am",
                        "Gear" = "gear"),
        selected = "area"
      )
    ),
    mainPanel(
      chartOutput("plot", "highcharts"),
      tags$script(src=theme_url, type='text/javascript')
    )
  )
))