plotlycurvenumber.R

# I'm trying to let the user select points and paint them in a certain colour, and if the user clicks on a point then paint that point a different colour.
# It looks like the pointNumber and curveNumber data that plotly returns are different for the same points. I'm not sure how curveNumber works, but to me it doesn't make sense yet :)
# Any help is appreciated!

library(plotly)
library(shiny)

ui <- fluidPage(
  plotlyOutput("plot")
)

server <- function(input, output, session) {
  output$plot <- renderPlotly({
    click_data <- event_data("plotly_click", source = "select")
    select_data <- event_data("plotly_selected", source = "select")
    data <- mtcars
    data$col <- "black"
    if (!is.null(select_data)) {
      cat(str(select_data))
      idx <- select_data$pointNumber + 1
      data[idx, "col"] <- "blue"
    }
    if (!is.null(click_data)) {
      cat(str(click_data))
      idx <- click_data$pointNumber + 1
      data[idx, "col"] <- "red"
    }
    p <- ggplot(data, aes(mpg, wt, col = I(col))) + geom_point()
    ggplotly(p, source = "select")
  })
}

shinyApp(ui, server)

plotlycurvenumber2.R

# This is very similar to the previous file, but I tried applying Carson's advise of setting the key aesthetic to row names

library(plotly)
library(shiny)

ui <- fluidPage(
  plotlyOutput("plot")
)

server <- function(input, output, session) {
  output$plot <- renderPlotly({
    click_data <- event_data("plotly_click", source = "select")
    select_data <- event_data("plotly_selected", source = "select")
    data <- mtcars
    key <- row.names(data)
    data$col <- "black"
    if (!is.null(select_data)) {
      cat(str(select_data))
      idx <- select_data$pointNumber + 1
      data[idx, "col"] <- "blue"
    }
    if (!is.null(click_data)) {
      cat(str(click_data))
      idx <- click_data$pointNumber + 1
      data[idx, "col"] <- "red"
    }
    p <- ggplot(data, aes(mpg, wt, col = I(col), key = key)) + geom_point()
    ggplotly(p, source = "select")
  })
}

shinyApp(ui, server)

Similar problem to romanhaa - does anybody have a neat solution for this? When using renderPlotly and not rendering a ggplot first, it doesn't seem trivial to keep track of rows efficiently. It's possible for example when encoding color with an integer, but the order gets thrown around within plotly if color is encoded as a string, or factor.

Is it possible to maintain the same zoom state after click/selection?

@asadow a little late but you can maintain the zoom state by using plotlyProxy to modify the plotly object instead of re-rendering it:

library(shiny)
library(plotly)

ui <- fluidPage(
  plotlyOutput("my_plot"),
  verbatimTextOutput("click"),
  verbatimTextOutput("selected")
)

server <- function(input, output, session) {
  
  nms <- row.names(mtcars)
  
  output$my_plot <- renderPlotly({
    p <- plot_ly(
      mtcars,
      x = ~mpg,
      y = ~wt,
      customdata = nms,
      selected = list(marker = list(color = "red")),
      type = "scatter",
      mode = "markers"
    ) |>
      layout(dragmode = "select") |>
      event_register("plotly_selected") |>
      event_register("plotly_click") |>
      event_register("plotly_doubleclick")
  })
  
  output$click <- renderPrint({
    d <- event_data("plotly_click")
    if (is.null(d)) "Click events appear here (double-click to clear)" else d
  })
  
  output$selected <- renderPrint({
    d <- event_data("plotly_selected")
    if (is.null(d)) "Selected points appear here (double-click to clear)" else d
  })
  
  plot_proxy <- plotlyProxy("my_plot", session, deferUntilFlush = TRUE)
  
  plotly_click <- reactive(event_data("plotly_click"))
  plotly_doubleclick <- reactive(event_data(event = "plotly_doubleclick", source="my_plot"))
  plotly_selected <- reactive(event_data(event = "plotly_selected", source="my_plot"))
  
  observeEvent(plotly_click(), {
    # plotlyProxyInvoke(plot_proxy, "restyle", list(selectedpoints = -1)) # deselect all points for all traces
    plotlyProxyInvoke(plot_proxy, "restyle", list(selectedpoints = list(I(plotly_click()$pointNumber))), plotly_click()$curveNumber)
  })
}

shinyApp(ui, server)

Here my related SO answer can be found.