Shiny: problems with renderUI reactivity

Question

I have a seemingly small but tricky problem with a reactive function in a Shiny App.

The app is designed to show a lineChart when a firm is selected, and show a bar chart of all firms when "All" is selected. For example when selecting:

Filter by Category 1= 3 and Filter by Category 1: 2 in the ui, only 4 firms remain in the firms drop down and I want to then be able to select firm A in the firms drop down to get a line chart for firm A.

The problem is that when i select firm A, it displays the lineChart for firm A for 1 second and then jumps back to "All".

I think the issue lies with following line:

output$firm <- renderUI({
   selectInput("firm", "Filter by Firm:",
            choices = c("All",as.character(unique(subset_data()$FIRM))))   
  })  

The choices I request are "All" and "firm X". It first creates the lineChart for firm X and then creates the chart as under "All". I thus tried to remove the "All" from the choices, but that did not work.

Any help much appreciated! Thanks

Here's a reproducible example:

Create sample data first:

set.seed(1)
df <- data.frame(FIRM=rep(LETTERS[1:7],each=10), CATEG_1=rbinom(70,4,0.9),CATEG_2=rbinom(70,1,0.2),date=as.Date("2014-01-01")+1:10,y1=sample(1:100,70))

ShinyApp:

library(shiny)
library(rCharts)
library(doBy)
library(plyr)

shinyApp(ui = 
shinyUI(pageWithSidebar(

# Application title
headerPanel("Example"),

           sidebarPanel(
         uiOutput("firm"),
        #  selectInput("firm", "Filter by firm:", 
        #   choices = unique(as.character(df))),
         selectInput("categ_1", "Filter by Category 1:",
                     choices = c("All",unique(as.character(df$CATEG_1)))),
         selectInput("date", "Filter by Date:", 
                     choices = c("All","Last 28 Days","Last Quarter")),
         selectInput("categ_2", "Filter by Category 2:", 
                     choices = c("All",unique(as.character(df$CATEG_2))))         
       ), #sidebarPanel

       mainPanel(
         h4("Example plot",style = "color:grey"),
         showOutput("plot", "nvd3")
       ) # mainPanel
     ) #sidebarLayout
 ) #shinyU
 , 
server = shinyServer(function(input, output, session) {  

subset_data <- reactive({df <- filter_data(df,input$firm,
                                         input$date,
                                         input$categ_1,
                                         input$categ_2)
                       shiny::validate(need(!is.null(df),"No data to display"))
                       return(df)})

  output$firm <- renderUI({
   selectInput("firm", "Filter by Firm:",
            choices = c("All",as.character(unique(subset_data()$FIRM))))   
  })        

  output$plot<-renderChart2({ build_plot(subset_data()) })

##############
#below are the functions used in the code
##############

 # function for date subsetting 

  filter_date<-function(df,dateRange="All"){
  filt <- df
  td <- max(as.Date(filt$date))
  if (dateRange=='Last 28 Days'){filt <-filt[filt$date>=(td-28),]}
  if (dateRange=='Last Quarter'){filt <-filt[filt$date>=(td-84),]}
  return(filt)
   }  # filter by date

 # function for data subsetting 

  filter_data<-function(df,firm=NULL,dateRange="All",categ_1=NULL,categ_2=NULL)
  { 
  filt<-filter_date(df,dateRange)

  if (!is.null(firm)) {
  if(firm!='All') {filt <- filt[filt$FIRM==firm,]}
  }
  if (!is.null(categ_1)){
  if (categ_1!='All') {filt <- filt[filt$CATEG_1==categ_1,]}
  } 
  if (!is.null(categ_2)) {
  if (categ_2!='All') {filt <- filt[filt$CATEG_2==categ_2,]} 
  }

  if(nrow(filt)==0) {filt <- NULL}
  return(filt)
  } # prepare data to be plotted

# function to create plot

  build_plot <- function(df) {
  plotData<-df
  # If 1 partner selected, time series is shown  
  if (length(as.character(unique(plotData$FIRM)))==1) {

  tabledta<-summaryBy(y1~FIRM+date,data=plotData,FUN=sum,keep.names=TRUE) 

  filler = expand.grid(FIRM=as.character(unique(df$FIRM)),
                     date=seq(min(tabledta$date),max(tabledta$date),by='1 day'))
  df = merge(filler,
           tabledta,
           by=c('date','FIRM'),
           all.x=T)
  df[is.na(df)]=0
  p <- nPlot(y1 ~ date, group = 'FIRM', data = df, type = 'lineChart')
  p$chart(margin=list(left=150))
  p$yAxis(showMaxMin = FALSE)
  p$xAxis(tickFormat ="#!function(d) {return d3.time.format('%Y-%m-%d')(new Date(d * 24 * 60 * 60 * 1000));}!#")
  p
  }
  # If "All" partners are selected, barchart of Top 5 is shown
  else{
  SummaryTab<-aggregate(y1~FIRM,data=plotData,FUN=sum)
  SummaryTab$rank=rank(SummaryTab$y1)
  SummaryTab$rank[SummaryTab$rank>5]<-6

  if (length(SummaryTab$rank)>5) {
  #Top 5 partners in terms of y1 are shown
  top5<-SummaryTab[SummaryTab$rank<=5,]
  # other partners are collapsed, shown as 1 entry

  others<-aggregate(y1~rank,data=SummaryTab,FUN=sum)  
  others<-others[others$rank==6,]
  others$FIRM<-"Others"

  # Create the summarytable to be plotted
  plotData=rbind(top5,others)}

  tabledta<-summaryBy(y1~FIRM,data=plotData,FUN=sum,keep.names=TRUE) 
  tabledta<-arrange(tabledta,y1) 
  #   if(is.null(tabledta)) {print("Input is an empty string")}

  p <- nPlot(y1 ~ FIRM,data = tabledta, type = 'multiBarHorizontalChart')    
  p$chart(margin=list(left=150))
  p$yAxis(showMaxMin = FALSE)
  p
  }

  }
  }) #shinyServer
  ) 

Answer 1

The problem is that output$firm is self-reactive in your code, because it depends on input$firm.

The output$firm expression generates a user interface for input$firm, which automatically triggers reevaluation of all reactive expressions that depend on input$form. One of such reactive expressions is output$firm itself (it depends on input$firm via subset_data()), so every call to output$firm will cause its recursive re-evaluation.

What you need is to isolate the subset_data() expression, which will prevent triggering on changes in subset_data():

output$firm <- renderUI({
 input$date
 input$categ_1
 input$categ_2
 selectInput("firm", "Filter by Firm:",
         choices = c("All",as.character(unique(isolate(subset_data()$FIRM)))))
})

Note that I inserted several input$... lines to make sure that output$firm will trigger on any change in these inputs.