Point selection with R Shiny

sparkler.R

library(shiny)
library(tidyverse)

mydata <- tibble::rowid_to_column(mpg)

ui <- fluidPage(
  titlePanel("Sparkler"),
  plotOutput("facet1", brush="facet1_brush"),
  textOutput("numsel"),
  actionButton("done", "Done")
)

server <- function(input, output) {
  selection <- reactiveValues(
    rows = numeric()
  )
  
  observeEvent(input$facet1_brush, {
    selection$rows  <- brushedPoints(mydata, input$facet1_brush)$rowid
  })
  
  plotdata <- reactive({
    mutate(mydata, selected = rowid %in% selection$rows)
  })
  
  output$facet1 <- renderPlot({
    ggplot(plotdata()) + 
      geom_point(aes(cty, hwy, color=selected))
  })
  
  output$numsel <- renderText({
    paste(length(selection$rows), "point(s) selected")
  })
  
  observeEvent(input$done, {
    stopApp(mydata[selection$rows,])
  })
}

# Run the application 
runApp(shinyApp(ui = ui, server = server))