Question

Update – 12/17/2012 9am CDT: example has been updated with demo data and full code. [/update].

Example Data: https://gist.github.com/4318774

Description:
I’ve been playing around with the new Shiny package (love it!) but don’t yet understand an error I’m getting when I runApp(""). Error is Error in tag("div", list(...)): argument is missing.

I’m trying to create an interactive web-app for graphical exploration of demographic data. I’m using the following as guides:
https://gist.github.com/4026749
http://rstudio.github.com/shiny/tutorial/

with options(error= recover), I get:

Listening on port 8100
Error in tag("div", list(...)) : argument is missing, with no default

Enter a frame number, or 0 to exit   

 1: runApp("//~~my app~~")
 2: tryCatch(while (TRUE) {
    serviceApp(ws_env)
}, finally = {
    timerCallbacks$clear()
    websocket_close(ws_env)
})
 3: tryCatchList(expr, classes, parentenv, handlers)
 4: serviceApp(ws_env)
 5: service(server = ws_env, timeout = timeout)
 6: server$static(j, J$wsinfo)
 7: handler(ws, header)
 8: handler(ws, header)
 9: local({
    cacheContext$with(function() {
        source(filePath, local = new.env(parent = .GlobalEnv))
    })
})
10: eval.parent(substitute(eval(quote(expr), envir)))
11: eval(expr, p)
12: eval(expr, envir, enclos)
13: eval(quote({
    cacheContext$with(function() {
        source(filePath, local = new.env(parent = .GlobalEnv))
    })

14: eval(expr, envir, enclos)
15: cacheContext$with(function() {
    source(filePath, local = new.env(parent = .GlobalEnv))
})
16: func()
17: source(filePath, local = new.env(parent = .GlobalEnv))
18: withVisible(eval(ei, envir))
19: eval(ei, envir)
20: eval(expr, envir, enclos)
21: ui.R#6: shinyUI(pageWithSidebar(headerPanel("Demographics Web Demo - Eglin Data"), sidebarPanel(textInput("plot.ti
22: force(ui)
23: pageWithSidebar(headerPanel("Demographics Web Demo - Eglin Data"), sidebarPanel(textInput("plot.title", "Title:", 
24: bootstrapPage(div(class = "container-fluid", div(class = "row-fluid", headerPanel), div(class = "row-fluid", sideb
25: tagList(importBootstrap(), list(...))
26: div(class = "container-fluid", div(class = "row-fluid", headerPanel), div(class = "row-fluid", sidebarPanel, mainP
27: tags$div(...)
28: tag("div", list(...))
29: div(class = "row-fluid", sidebarPanel, mainPanel)
30: tags$div(...)
31: tag("div", list(...))
32: sidebarPanel(textInput("plot.title", "Title:", "Population Pyramid of Members"), wellPanel(p(strong("Demographic o
33: div(class = "span4", tags$form(class = "well", ...))
34: tags$div(...)
35: tag("div", list(...))
36: tags$form(class = "well", ...)
37: tag("form", list(...))
38: wellPanel(p(strong("Demographic of Interest")), checkboxInput(inputId = "age_dist", label = "Age Distribution", va
39: div(class = "well", ...)
40: tags$div(...)
41: tag("div", list(...))

I tried investigating what was going on, but ?checkboxInput made the code look accurate. It also is pretty much a direct copy of the “stocks” example from RStudio (github linked above)

ui.R / Server.R code:
ui.R

library(shiny)

shinyUI(pageWithSidebar(
  # application title
  headerPanel("Demographics Web Demo - Eglin Data"),

  # sidebar with controls to allow user to define graphical elements and how
  # they want them displayed.
  sidebarPanel(
    # allow the user to write a plot Title
    textInput("plot.title", "Title:", "Population Pyramid of Members"),

    # allow the user to determine which demographic they want to plot
    wellPanel(
      p(strong("Demographic of Interest")),
      checkboxInput(inputId = "age_dist",    label = "Age Distribution",      value = TRUE),
      checkboxInput(inputId = "wealth_dist", label = "Household Wealth",      value = FALSE),
      checkboxInput(inputId = "home_val",    label = "Home Value",            value = FALSE),
      checkboxInput(inputId = "ed_level",    label = "Members' Education",    value = FALSE),
      checkboxInput(inputId = "inc_level",   label = "Members' Est. Income",  value = FALSE),
      checkboxInput(inputId = "h_own",       label = "Homeownership",         value = FALSE),
    ),

    # allow the user to determine age-bracket size. Input used in plotting
    sliderInput("age_cut", "Select Size of Age Brackets:",
                min= 3, max= 20, value= 5),

    # allow the user to subset their demographics by age range
    #sliderInput("age_sub", "Please select the age range you would like to 'zoom-in' on:",
    #            min= 0, max= 120, value= c(15,65)),
  ),


  # display the appropriate graphics based on the user selections defined 
  # above.
  mainPanel(
    h3(textOutput("caption")),

    conditionalPanel(condition= "input.age_dist",
                     plotOutput(outputId= "plot_age")),
    conditionalPanel(condition= "input.wealth_dist",
                     plotOutput(outputId= "plot_wealth")),
    conditionalPanel(condition= "input.home_val",
                     plotOutput(outputId= "plot_home_value")),
    conditionalPanel(condition= "input.ed_level",
                     plotOutput(outputId= "plot_edu")),
    conditionalPanel(condition= "input.inc_level",
                     plotOutput(outputId= "plot_inc")),
    conditionalPanel(condition= "input.h_own",
                     plotOutput(outputId= "plot_h_own"))
  )
))

server.R

# require packages
if (!require(ggplot2)) {
  stop("This application requires ggplot2. To install it, please run 'install.packages(\"ggplot2\")'.\n")
}
if (!require(plotrix)) {
  stop("This application requires plotrix. To install it, please run 'install.packages(\"plotrix\")'.\n")
}
library(shiny)

# load example demo data
load("~~you'll need to load the test data here")


shinyServer(function(input, output) {

  # reactive function based on user input for plot title
  # This function is automatically called to update the display
  output$caption <- reactiveText(function() {
    input$plot.title
  })

  updateAge_f <- reactive(function() {
    # re-define age brackets based on user input
    demos$age_f <- ordered(cut(demos$age, breaks= c(seq(0, max(demos$age), input$age_cut)),
                               include.lowest= T))
  })

  # Generate a plot of the Members' age distribution
  output$plot_age <- reactivePlot(function() { 
    # call to update age factor if needed
    updateAge_f()
    # develop input vectors
    male <- as.vector(table(demos$age_f, demos$female_flag)[,1]/summary(demos$female_flag)[1] * 100)
    women <- as.vector(table(demos$age_f, demos$female_flag)[,2]/summary(demos$female_flag)[2] * 100)
    # create plot
    pyramid.plot(lx= male, rx= women,
                 labels= levels(demos$age_f),
                 lxcol= "blue", rxcol= "pink",
                 main= "Population Pyramid of Members",
                 gap= 2, labelcex= .75)
  })

  # generate a plot of members' wealth codes
  output$plot_wealth <- reactivePlot(function() { 
    # call to update age factor if needed
    updateAge_f()

    if (input$factor_age == TRUE) {
      ggplot(demos2, aes(wealth)) + geom_bar() + 
        facet_wrap(~ age_f, ncol= 3) + theme_bw() +
        labs(title= "Wealth of Members by Age Bracket",
             y= "Count of Individuals",
             x= "Decile of Wealth (by State)") +
        theme(axis.text.x= element_text(angle= 90))
    } else if (input$factor_age == FALSE) {
      ggplot(demos2, aes(wealth)) + geom_bar() + 
        theme_bw() +
        labs(title= "Wealth of Members of your Members",
             y= "Count of Individuals",
             x= "Decile of Wealth (by State)") +
        theme(axis.text.x= element_text(angle= 90))
    }
  })

  # generate a plot of home value of members' properties
  output$plot_home_value <- reactivePlot(function() { 
    # call to update age factor if needed
    updateAge_f()

    if (input$factor_age == TRUE) {
      ggplot(demos2, aes(home_value)) + geom_bar() + 
        facet_wrap(~ age_f, ncol= 3) + theme_bw() +
        labs(title= "Home Value by Age Bracket",
             y= "Count of Individuals",
             x= "Home Value") +
        theme(axis.text.x= element_text(angle= 90))
    } else if (input$factor_age == FALSE) {
      ggplot(demos2, aes(home_value)) + geom_bar() + 
        theme_bw() +
        labs(title= "Home Value of your Members",
             y= "Count of Individuals",
             x= "Home Value") +
        theme(axis.text.x= element_text(angle= 90))
    }
  })

  # generate a plot of education distribution
  output$plot_edu <- reactivePlot(function() { 
    # call to update age factor if needed
    updateAge_f()

    if (input$factor_age == TRUE) {
      ggplot(demos2, aes(ed_code)) + geom_bar() + 
        facet_wrap(~ age_f, ncol= 3) + theme_bw() +
        labs(title= "Education Level by Age Bracket",
             y= "Count of Individuals",
             x= "Education Level") +
        theme(axis.text.x= element_text(angle= 90))
    } else if (input$factor_age == FALSE) {
      ggplot(demos2, aes(ed_code)) + geom_bar() + 
        theme_bw() +
        labs(title= "Education Level of your Members",
             y= "Count of Individuals",
             x= "Education Level") +
        theme(axis.text.x= element_text(angle= 90))
    }
  })

  # generate a plot of members' estimated income levels
  output$plot_inc <- reactivePlot(function() { 
    # call to update age factor if needed
    updateAge_f()

    if (input$factor_age == TRUE) {
      ggplot(demos2, aes(inc)) + geom_bar() + 
        facet_wrap(~ age_f, ncol= 3) + theme_bw() +
        labs(title= "Estimated Income by Age Bracket",
             y= "Count of Individuals",
             x= "Estimated Income Range") +
        theme(axis.text.x= element_text(angle= 90))
    } else if (input$factor_age == FALSE) {
      ggplot(demos2, aes(inc)) + geom_bar() + 
        theme_bw() +
        labs(title= "Estimated Income of your Members",
             y= "Count of Individuals",
             x= "Estimated Income Range") +
        theme(axis.text.x= element_text(angle= 90))
    }
  })

  # generate a plot of members' homeownership
  output$plot_h_own <- reactivePlot(function() { 
    # call to update age factor if needed
    updateAge_f()

    if (input$factor_age == TRUE) {
      ggplot(demos2, aes(homeOwner)) + geom_bar() + 
        facet_wrap(~ age_f, ncol= 3) + theme_bw() +
        labs(title= "Home Ownership by Age Bracket",
             y= "Count of Individuals",
             x= "Home Owner / Renter") +
        theme(axis.text.x= element_text(angle= 90))
    } else if (input$factor_age == FALSE) {
      ggplot(demos2, aes(homeOwner)) + geom_bar() + 
        theme_bw() +
        labs(title= "Home Ownership of your Members",
             y= "Count of Individuals",
             x= "Home Owner / Renter") +
        theme(axis.text.x= element_text(angle= 90))
    }
  })
})

Any help would be appreciated, still trying to learn shiny (like everyone else).

Answer 1

In ui.R, you should not have a comma at the end of this line:

sliderInput("age_cut", "Select Size of Age Brackets:",
            min= 3, max= 20, value= 5),

There also shouldn’t be a comma at the end of this line

checkboxInput(inputId = "h_own",       label = "Homeownership",         value = FALSE),

In general, you shouldn’t have a comma after the last component of a section. Just like with any R function, you don’t usually end the function call with a comma. e.g. sum(5,) gives an error.