Shiny Sampling Distributions

server.R

library(shiny)
library(mosaic)
require(lattice)
require(datasets)

# Define server logic required to generate and plot a random distribution
shinyServer(
  function(input, output) {
    popDist <- reactive( function() input$popDist )
    
    
    input$n <- reactive( function() input$n )
    
    params <- reactive( function() {
      switch(popDist(),
             "normal" = list(mean=input$mean, sd=input$sd),
             "beta" = list(shape1=input$shape1, shape2=input$shape2),
             "gamma" = list(shape=input$shape, scale=input$scale),
             "weibull" = list(shape=input$shape, scale=input$scale)
      )} )
    
    rdist <- reactive( function() {
      switch(popDist(),
             "normal" = "rnorm",
             "beta" = "rbeta",
             "gamma" = "rgamma",
             "weibull" = "rweibull"
      )} )
    
    distName <- reactive( function() {
      switch(popDist(),
             "normal" = "norm",
             "beta" = "beta",
             "gamma" = "gamma",
             "weibull" = "weibull"
      )} )
    
    samplingDist <- reactive( function() 
      replicate(5000, mean(
        do.call(rdist(), c( list(input$n), params() ))
      ))
    )
    
    output$mainText <- reactive(function(){ paste( "Population:", popDist() ) })
    output$samplingDistHeader <- reactive(function(){ 
      paste( "Sampling Distribution for Sample Means (n=", as.character(input$n), ")", sep="") 
    })
    
    output$populationPlot <- reactivePlot(function() {
      print(plotDist( distName() , params=params(), par.settings=col.mosaic() ))
    })
    
    output$histogram<- reactivePlot(function() {
      print(xhistogram( ~ samplingDist(), par.settings=col.mosaic() ))
    })
    
    output$densityplot<- reactivePlot(function() {
      print(densityplot( ~ samplingDist(), par.settings=col.mosaic() ))
    })
    
    output$qqPlot<- reactivePlot(function() {
      print(qqmath( samplingDist(), par.settings=col.mosaic() ))
    })
    
  })

ui.R

library(shiny)

shinyUI(pageWithSidebar(
  
  # Application title
  headerPanel("Sampling Distributions"),
  
  # Sidebar with a slider input for number of observations
  sidebarPanel(
    sliderInput("n", 
                "Sample size:", 
                min = 1, 
                max = 400, 
                value = 2),
    
    selectInput("popDist", "Population",
                list("Normal" = "normal",
                     "Beta" = "beta",
                     "Gamma" = "gamma",
                     "Weibull" = "weibull"
                )
    ),   # end selectInput
    
    conditionalPanel(
      condition = "input.popDist == 'beta'",
      sliderInput("shape1", "shape1: ", min=0.1, max=10, value=1, step=0.05),
      sliderInput("shape2", "shape2: ", min=0.1, max=10, value=1, step=0.05)
    ),
    conditionalPanel(
      condition = "input.popDist == 'gamma'",
      sliderInput("shape", "shape: ", min=0.1, max=10, value=1, step=0.05),
      sliderInput("scale", "scale: ", min=0.1, max=10, value=1, step=0.05)
    ),
    conditionalPanel(
      condition = "input.popDist == 'weibull'",
      sliderInput("shape", "shape: ", min=0.1, max=10, value=1, step=0.05),
      sliderInput("scale", "scale: ", min=0.1, max=10, value=1, step=0.05)
    ),
    conditionalPanel(
      condition = "input.popDist == 'normal'",
      sliderInput("mean", "mean: ", min=0, max=400, value=0),
      sliderInput("sd", "st. dev.: ", min=0.1, max=20, value=1, step=.1)
    )
  ),   # end sidebarPanel
  
  
  mainPanel(
    h3(textOutput("mainText")),
    plotOutput("populationPlot",width="250px", height="180px"),
    h3(textOutput("samplingDistHeader")),
    tabsetPanel(
      tabPanel("Histogram", plotOutput('histogram',height="220px",width="500px")),
      tabPanel("Density plot", plotOutput('densityplot', height="220px",width="500px")),
      tabPanel("Normal quantile plot", plotOutput('qqPlot', height="220px",width="500px"))
    )
  )
))