server.R

library(shiny)
library(dplyr)

df1 <- data.frame(id = c(1,2,3,4,5), number = c(20,30,23,25,34), ds =  c(1,2,3,42,2))
df2 <- data.frame(id = c(1,2), number = c(33,40), ds = c(1,2))

shinyServer(function(input, output) {
  
  datasetInput <- reactive({
    switch(input$dataset,
           "df1" = df1,
           "df2" = df2)
  })
  
  output$yvars <- renderUI({
    if (identical(df1,datasetInput())){
      axis_vars_y <- c("number" = "number", "number2" = "number2")
      selectInput("yvar", "X-axis variable", axis_vars_y, selected = "id")
    }
    else{
      axis_vars_y <- c("number" = "number")
      selectInput("yvar", "X-axis variable", axis_vars_y, selected = "id")
    }
  })
  
  axis_vara_y <- reactive({
    switch(input$yvar,
           number = 2,
           number2 = 3)
  }) 
  
  output$slider <- renderUI({
    sliderInput("inslider","Slider", min   = min(datasetInput()[,axis_vara_y()]),
                max   = max(datasetInput()[,axis_vara_y()]),
                value = c(min(datasetInput()[,axis_vara_y()]), 
                          max(datasetInput()[,axis_vara_y()])))
  })
  
  data <- reactive({
    df<-datasetInput()
    axisData <- 2
    if(!is.null(input$yvar)){
      axisData <- input$yvar
    }
    if(!is.null(input$inslider)){
      filteredData <- filteredData %>%
        filter(filteredData[,axisData] >= input$inslider[1],
               filteredData[,axisData] <= input$inslider[2])
    }
    filteredData
  })

  vis <- reactive({
    yvar <- prop("y", as.symbol(input$yvar))
    
    data %>%
      ggvis(~id, y = yvar) %>%
      layer_points(fill = ~factor(id)) %>%
      scale_nominal("fill", range = c("red","blue","green","yellow","black"))
    
  })
  vis %>% bind_shiny("plot")
})

ui.R

library(shiny)
library(ggvis)

shinyUI(fluidPage(
  
  titlePanel(""),
  
  sidebarLayout(
    sidebarPanel(
      radioButtons("dataset", label = h4("Product level"),
                   choices = list("Item" = "df1", "Task" = "df2")),
      uiOutput("yvars"),
      uiOutput("slider")
    ),
    mainPanel(
      ggvisOutput("plot")
    )
  )
))