R shiny : checkboxGroupInput value

Question

I'm new to R and I have this code in Ui.R :

library(shiny)

ui <- shinyUI(fluidPage(

  titlePanel("Test 1"),

  sidebarLayout(
    sidebarPanel(
      checkboxGroupInput("sex", "sex", c("Men", "Women")),
      textOutput("number")
   ),

   mainPanel(

   )
  )
))

And this code in Server.R :

server <- shinyServer(function(session, input, output) {

  observeEvent(input$sex, {
    if (input$sex == "Men"){s<-1}
    number<-as.numeric(s)

    if (input$sex == "Women"){s<-2}
    number<-as.numeric(s)

    if (input$sex == "Men" & input$sex == "Women"){s<-5}
    number<-as.numeric(s)

    if (is.null(input$sex)) {s<-10}
    number<-as.numeric(s)

    output$number<-renderText({number})
  })
  })

So, I don't understand why "number" does not take value 5 when I check both check boxes, and why "number" does not take value 10 if I uncheck both boxes ?

If you could help me to understand please.

Thank you very much.

EDIT : how to deselect checkboxGrouInput "dynamic" ?

library(shiny)

ui <- shinyUI(fluidPage(

  titlePanel("Test 1"),

  sidebarLayout(
    sidebarPanel(
      checkboxGroupInput(inputId = "sex", label = "sex",choices =  
                                    c("Men", "Women", "Children")),
      textOutput("number")
      ),

      mainPanel(
        checkboxGroupInput(inputId = "dynamic", label = "", choices = 
                                  list("Answer 1"="01", "Answer 2"="02", 
                                       "Answer 3"="03", "Answer 4"="04",
                                       "Answer 5"="05", "Answer 6"="06", 
                                       "Answer 7"="07", "Answer 8"="08", 
                                       "Answer 9"="09", "Answer 10"="10",
                                    "Answer 11"="11", "Answer 12"="12"))
       )
    )
  ))

And Server.R :

server <- shinyServer(function(session, input, output) { 

  output$number<-renderText({ 

    if (is.null(input$sex) ){return(10)
      updateCheckboxGroupInput(session,"dynamic",selected=character(0))}

    men      <- "Men"       %in% input$sex
    women    <- "Women"     %in% input$sex
    children <- "Children"  %in% input$sex

    if (men & women & children){
      s <- 8
      updateCheckboxGroupInput(session,"dynamic",
                             selected=list("01","02","03","04","05","06",
                                "07","08","09","10","11","12"))

      } else if (men & women){
        s <- 5
        updateCheckboxGroupInput(session,"dynamic",
                  selected=list("01","02","03","04","05","06","07","08"))

      } else if (men){
         s <-1
         updateCheckboxGroupInput(session,"dynamic",
                                    selected=list("01","02","03","04"))

      } else if (women){
         s <-2
         updateCheckboxGroupInput(session,"dynamic",
                                    selected=list("05","06","07","08"))

       } else if (children) {
          s <- 3
          updateCheckboxGroupInput(session,"dynamic",
                                    selected=list("09","10","11","12"))
       }  

       return(as.numeric(s)) 
   })
 })

Thank you very very much.

Eduardo Bergel · Answer 1 · 2016-10-22T16:49:08.630

A few thing to consider in your code:

1) if both male and female are selected, then input$sex has length=2 (chr [1:2] "Men" "Women"). This line wont work.

(input$sex == "Men" & input$sex == "Women")

2) At app init input$sex is NULL, and you can not use a null in an if statement as in

if (input$sex == "Men")

3) you dont need observeEvent. renderText is reactive to input$sex.

I made some changes to your code

library(shiny)

ui <- shinyUI(fluidPage(

  titlePanel("Test 1"),

  sidebarLayout(
    sidebarPanel(
      checkboxGroupInput(inputId = "sex", label = "sex",choices =  c("Men", "Women")),
      textOutput("number")
    ),

    mainPanel()
  )
))

server <- shinyServer(function(session, input, output) { 

  output$number<-renderText({ 

    if (is.null(input$sex) ){return(10)}

    if (length(input$sex) ==1){
        if (input$sex == "Men"){
          s<-1
        } else if (input$sex == "Women"){
          s<-2
        }
    } else{
        return(5)
    } 

    return(as.numeric(s))
  })
})

shiny::shinyApp(ui, server)

update - if you have more options

library(shiny)

ui <- shinyUI(fluidPage(

  titlePanel("Test 1"),

  sidebarLayout(
    sidebarPanel(
      checkboxGroupInput(inputId = "sex", label = "sex",choices =  c("Men", "Women", "Children")),
      textOutput("number")
    ),

    mainPanel()
  )
))

server <- shinyServer(function(session, input, output) { 

  output$number<-renderText({ 

    if (is.null(input$sex) ){return(10)}

    men      <- "Men"       %in% input$sex
    women    <- "Women"     %in% input$sex
    children <- "Children"  %in% input$sex

    if (men & women & children){
      s <- 8 
    } else if (men & women){
      s <- 5
    } else if (men){
      s <-1
    } else if (women){
      s <-2
    } else if (children) {
      s <- 3
    }  

    return(as.numeric(s)) 
  })
})

shiny::shinyApp(ui, server)

Oh great ! Thanks a lot Ron for your explanations. I understand well better now. Just one more question : I have to add one box in the checkboxGroupInput : children. How can I distinguish choices : Men-Women/Men-Children/Women-Children as the length is the same ? Thank you again. — Mickey_NC, Oct 22 '16 at 15:40
See updated code. There are more elegant ways to do this, but this one follow the ideas in your code. — Eduardo Bergel, Oct 22 '16 at 16:50
Thank you so much Ron for helping. You're a king. But once I have completed my code, I still have a little problem about deselecting the checkboxGroupInput "dynamic" when none of the box of the checkboxGroupInput "sex" is checked. I tried "selected = NULL, FALSE and character(0) but none of them works. Do you know why ? Please, see my edited code. Thank you again Ron. — Mickey_NC, Oct 23 '16 at 05:59

R shiny : checkboxGroupInput value

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