How to create IF statement with reactive values in R ( Shiny )

Question

Beginner to R and shiny here! Tried to make a minimal working example... I want to check a condition on a reactive input value. What am I doing wrong?

librar         


        

Answer 1

You just need to use reactive with your if so that shiny knows that y changes when x does.

library(shiny)

ui<-fluidPage(

  numericInput(inputId="a", label=NULL, value=0),
  textOutput(outputId="out")
)

server <- function(input, output) {
  x <- reactive(input$a)
  y <- reactive( if (x()<4) 1 else 0 )

  output$out <- renderText({ y() })
}

shinyApp(ui = ui, server = server)