Make upper value of R shiny slider range always be higher than lower value

Question

I have a slider that looks like this:

The code for the slider is as follows:

UI:

fluidRow(column(12,
                    uiOutput("slider")))

SERVER:

mindate <- "2011-04-01"
maxdate <- "2017-03-31"

    output$slider <- renderUI({
        sliderInput("timeperiod", "Time Period:",
                    min=as.Date(mindate, origin='1970-01-01'),
                    max=as.Date(maxdate, origin='1970-01-01'),
                    value=c(as.Date(mindate, origin='1970-01-01'),
                            as.Date(maxdate, origin='1970-01-01')),
                    timeFormat='%b-%y', dragRange = TRUE, width='700px')
      })

Currently if you move the slider inputs they can be put as the same value like this:

Is there a way so that I can always keep the upper value of the slider a certain amount of ticks above the bottom value of the slider?

I want the minimum and the maximum to stay the same. I want the lower range of the upper value to be greater than the lower value and never be equal. Also, The end date cannot go before the start date by default, I am worried about showing too little data and I am not worried about it breaking because the range flips. — Dustin Knight, May 04 '17 at 14:26

score 3 · Accepted Answer · edited May 23 '17 at 12:02

You can add 31 days to the datetime object you have, however that is crude. Other ways of adding a month you can have a look here: Add a month to a Date

  observeEvent(input$timeperiod,{
    if(input$timeperiod[1] == input$timeperiod[2]){
      updateSliderInput(session, "timeperiod", value=c(input$timeperiod[1],(input$timeperiod[1]+31)))
    }
  })

Edit: To use the dates later on You can access the dates via the sliderMonth$Month reactive I've created

rm(list=ls())
library(shiny)

monthStart <- function(x) {
  x <- as.POSIXlt(x)
  x$mday <- 1
  as.Date(x)
}

mindate <- "2011-04-01"
maxdate <- "2017-03-31"

ui <- fluidPage(
  mainPanel(uiOutput("slider"),textOutput("SliderText"))
)

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

  observeEvent(input$timeperiod,{
    if(input$timeperiod[1] == input$timeperiod[2]){
      updateSliderInput(session, "timeperiod", value=c(input$timeperiod[1],(input$timeperiod[1]+31)))
    }
  })

  output$slider <- renderUI({
    sliderInput("timeperiod", "Time Period:",
                min=as.Date(mindate, origin='1970-01-01'),
                max=as.Date(maxdate, origin='1970-01-01'),
                value=c(as.Date(mindate, origin='1970-01-01'),as.Date(maxdate, origin='1970-01-01')),
                timeFormat='%b-%y', dragRange = TRUE, width='700px')
  })

  sliderMonth <- reactiveValues()
  observeEvent(input$timeperiod,{
    full.date <- as.POSIXct(input$timeperiod, tz="GMT")
    sliderMonth$Month <- as.character(monthStart(full.date))
  })
  output$SliderText <- renderText({sliderMonth$Month})
}
shinyApp(ui, server)

This is exactly the idea I was looking for. I may experiment with lubridate to handle the month addition. — Dustin Knight, May 04 '17 at 18:31

Make upper value of R shiny slider range always be higher than lower value

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