Retrieve Selected Points from ggplotly in Another Part of Shiny App

Question

Desired Outcome

I would like to be able to click a point in my plotly::ggplotly() graph within my {shiny} app and then display some info about that point in a separate output below.

MRE

In this simple example I can make it display the curveNumber, pointNumber, x, y, but it's not easy to unambiguously retrieve a particular data point from my original data from these values. I've read about using key within the plotly::renderPlotly() call although I'm not sure how I'd access that in a separate part of the app.

library(tidyverse)
library(plotly)
library(shiny)

# UI  ----
ui <- fluidPage(plotlyOutput("plot"),
                verbatimTextOutput("click"))

# server  ----
server <- function(input, output) {
  output$plot <- renderPlotly({
    
    p <- mtcars %>% 
      rownames_to_column("car") %>% 
      ggplot(aes(x = disp, y = mpg, color = factor(cyl),
                 label = car)) +
      geom_point(size = 4, alpha = 0.7)
    
    ggplotly(p) %>% 
      event_register("plotly_click")
  })
  
  output$click <- renderPrint({
    point <- event_data(event = "plotly_click", priority = "event")
    if (is.null(point)) "No Point Selected" else point
  })
}

# app ----
shinyApp(ui = ui, server = server)

Answer 1

Using code from here I figured out how to use key to identify the points and then retrieve that elsewhere from the event_data().

library(tidyverse)
library(plotly)
library(shiny)

d <-  mtcars %>% 
  rownames_to_column("car")

# UI  ----
ui <- fluidPage(plotlyOutput("plot"),
                tableOutput("click"))

# server  ----
server <- function(input, output) {
  output$plot <- renderPlotly({
    
    key <- d$car
    
    p <- d %>% 
      ggplot(aes(x = disp, y = mpg, color = factor(cyl),
                 key = key)) +
      geom_point(size = 4, alpha = 0.7)
    
    ggplotly(p) %>% 
      event_register("plotly_click")
  })
  
  output$click <- renderTable({
    point <- event_data(event = "plotly_click", priority = "event")
    req(point) # to avoid error if no point is clicked
    filter(d, car == point$key) # use the key to find selected point
  })
}

# app ----
shinyApp(ui = ui, server = server)