Trying to get the difference of range sliderInput in R Shiny

January 30, 2022

I’m working through an R Shiny tutorial, and decided to veer off the path, but I’m lost at the moment. A previous exercise had me create a range slider, and I checked the docs to fancy it up with arguments. Now what I’m trying to do is create a textOutput below it to show the value of the difference between the min and max.

library(shiny)

ui <- fluidPage(
  sliderInput("rang", "Range", value = c(100, 2000), min = 0, max = 15000, 
              sep = ",", pre = "$", ticks = FALSE, dragRange = TRUE,
              width = "600px"),
  textOutput(costDiff())
)

server <- function(input, output, session) {
  costDiff <- reactive({
    costDiff <- input$rang[2] - input$rang[1]
  }) 
  
  output$costDiff <- renderText("$",{
    costDiff()
  })
}

shinyApp(ui, server)

I’m receiving:

Error in costDiff() : could not find function "costDiff"

Thanks in advance for your help!

>Solution :

Try this:

library(shiny)

ui <- fluidPage(
    sliderInput("rang", "Range", value = c(100, 2000), min = 0, max = 15000, 
                sep = ",", pre = "$", ticks = FALSE, dragRange = TRUE,
                width = "600px"),
    textOutput('costDiff')
)

server <- function(input, output, session) {
    costDiff <- reactive({
        input$rang[2] - input$rang[1]
    }) 
    
    output$costDiff <- renderText({
        paste('$', costDiff())
    })
}

shinyApp(ui, server)