Plotly highlight problem in R Shiny: Nothing is highlighted

Question

I am trying to add a feature in my Shiny app where a user can click a point on a scatterplot and it will be highlighted. This seems simple enough, but in my example below, I can't seem to get anything to be highlighted at all, no matter how many variations I try. I've looked through the advice in this post and this post, but they don't seem to help.

Any insight would be greatly appreciated!

# Define UI
ui <- fluidPage(

  fluidRow(
    
    column(6,
           h3("Scatterplot"),
           plotlyOutput("phylo_tree")),
  )
)


# Define server logic
server <- function(input, output) {
  

  
  # Phylogenetic Tree
  output$phylo_tree <- renderPlotly({

    
    # Create a scatter plot using plot_ly
    scatter_plot <- plot_ly(data = mtcars, x = ~mpg, y = ~wt, type = "scatter", mode = "markers",
                            color = ~cyl, size = ~hp, text = ~paste("Car: ", rownames(mtcars)))%>%
      # Highlight selected point 
      highlight(~mpg, on = "plotly_click",off = "plotly_doubleclick")
    
    
    
    scatter_plot
  })

}


# Run the application
shinyApp(ui, server)

I've tried including many variations of the arguments documented here, but I consistently get the same result: In the R Shiny app, nothing is highlighted when clicked.

Answer 1

This is not a problem with the shiny framework, but with the plotly code itself. Changing it to

scatter_plot <- mtcars |> highlight_key(~mpg) |>
      plot_ly(x = ~mpg,y = ~wt,type = "scatter",mode = "markers",color = ~cyl,
              size = ~hp,text = paste("Car: ",rownames(mtcars))) |>
      highlight(on = "plotly_click",off = "plotly_doubleclick")

should do what you want.