simple dynamic ui shiny example

global.R

#Global function for test of DRG State Hospital display 
# 29 July 2013 Kevin Little, Ph.D.  

#create data elements:  for each state, there are multiple hospitals that report
#values for multiple DRGs
State<-as.factor(rep(c("CA","CA","CA","CA","NJ","NJ","NJ","WY","WY"),3))
DRG<-as.factor(rep(c("101","102","103"),each=9))
Hospital<-as.factor(rep(c("C1","C2","C3","C4","N1","N2","N3","W1","W2"),3))


set.seed(1234)
x1<-10+rnorm(27)
x2<-x1+0.5*rnorm(27)
#now create a data frame
df_test<-cbind.data.frame(DRG,State,Hospital,x1,x2)

DRGName<-levels(df_test$DRG)
names(DRGName)<-DRGName
States<-levels(df_test$State)

#INITIALIZE HOSPITAL NAME LIST
StateHospitalNames<-vector("list",3)
HospNames<-function(i){
  ds<-as.factor(df_test[df_test$State==States[i],3])
  ds<-droplevels(ds)
  dss<-levels(ds)
}

for(i in 1:3){
  StateHospitalNames[[i]]<-HospNames(i)
}

server.R

#server.R
#accept input string of state name from ui, pass back hospital within state; create
# data summaries for DRG, for state, and for hospital within state.
# library(googleVis)
# suppressPackageStartupMessages(library(googleVis))

shinyServer(function(input, output) {
  StateDataInput <- reactive({
#     cat(as.character(paste(input$State,"Z ")))
    d3<-df_test[df_test[,2]==input$State,]
    d3<-droplevels(d3)
    return(d3)
  })
  
  DRGDataInput<-reactive({
    d4<-df_test[df_test[,1]==input$DRG,]
    d4<-droplevels(d4)
    return(d4)
  })
#The next code creates a reactive drop down list, allowing you to choose a hospital
  #for a state.
  output$HospList<-renderUI({
     data<-StateDataInput()
     if(is.null(data)) return(NULL)
     HospList<-levels(StateDataInput()$Hospital)
     selectInput("HospList","Choose Hospital", HospList)
   })
  

  output$summary1 <- renderPrint({
    dataset <- DRGDataInput()
    summary(dataset)
  })
   output$summary2 <- renderPrint({
     dataset2 <- StateDataInput()
     summary(dataset2)
   })
  
   output$summary3 <- renderPrint({
     dataset3 <- StateDataInput()[StateDataInput()$DRG==input$DRG & StateDataInput()$Hospital==input$HospList,]
     dataset3<-droplevels(dataset3)
     summary(dataset3)
     })

})

ui.R

# ui.R
# create drop down lists for DRG and state (fixed) and hospital within state (dynamic)
shinyUI(pageWithSidebar(
  headerPanel("2011 CMS $ Charged and Paid by DRG and state"),
  sidebarPanel(
    selectInput("DRG","Choose a DRG:",
                choices = DRGName),
    selectInput("State", "Choose a state:", 
                choices = States),
    uiOutput("HospList")
    ),
  

  
 #Display some output
  mainPanel(
    tabsetPanel(
      tabPanel("DRG", verbatimTextOutput("summary1")), 
      tabPanel("State",verbatimTextOutput("summary2")),
      tabPanel("Hospital",verbatimTextOutput("summary3"))
      ))

))