Shiny / Plotly: Update plot with labels of only selected points

Question

Using R Shiny and plotly I created a interactive scatter plot.

How can I modify my code to interactively label only the points which were selected by the user?

Thank you so much for your help! All the best, Christian

library(plotly)
library(shiny)
library(dplyr)

data <- data.frame(matrix(runif(500,0,1000), ncol = 2, nrow = 100)) %>%
  mutate(ID = row_number())

ui <- fluidPage(
  plotlyOutput("plot"),
  verbatimTextOutput("hover"),
  verbatimTextOutput("click"),
  verbatimTextOutput("brush"),
  verbatimTextOutput("zoom"))

server <- function(input, output, session) {

  output$plot <- renderPlotly({
    p <- ggplot(data, aes(x = X1, y = X2, key = ID)) +
      geom_point()
    ggplotly(p) %>% layout(dragmode = "select")
  })
}

shinyApp(ui, server)

I don't understand, your example is not reactive at all and gets never replotted? Anyway, you can update plotly objects without complete redraw using an observer plotlyProxy. — AEF
– AEF, Commented Mar 27, 2019 at 13:58
Thank you a lot for your comment, AEF! Now I updated my question and added a plot to make it clearer. — Christian
– Christian, Commented Mar 27, 2019 at 15:41

Tom · Accepted Answer · 2019-03-27 19:27:10Z

2

Below is a possible solution. I use a reactive function to "label" selected points. I wasn't sure how exactly you want to display the IDs for selected points. The code adds the ID as text when a point is selected. Also, I add some jitter to move the IDs away from the points.

library(plotly)
library(shiny)
library(dplyr)

data <- data.frame(matrix(runif(500,0,1000), ncol = 2, nrow = 100)) %>%
  mutate(ID = row_number())

ui <- fluidPage(
  plotlyOutput("plot"),
  verbatimTextOutput("hover"),
  verbatimTextOutput("click"),
  verbatimTextOutput("brush"),
  verbatimTextOutput("zoom"))

server <- function(input, output, session) {
  output$plot <- renderPlotly({
    data <- get_data()
    p <- ggplot(data, aes(x = X1, y = X2, key = ID)) +
      geom_point() + geom_text(data=subset(data, show_id),aes(X1,X2,label=ID), position = position_jitter(width = 20,height = 20))
    ggplotly(p, source = "subset") %>% layout(dragmode = "select")
  })

  get_data <- reactive({
    event.data <- event_data("plotly_selected", source = "subset")
    data <- data %>% mutate(show_id = FALSE)
    if (!is.null(event.data)) {
      data$show_id[event.data$pointNumber + 1] <- TRUE
    }
    data
  })
}

shinyApp(ui, server)

answered Mar 27, 2019 at 19:27

Tom

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1 Comment

Christian Over a year ago

Thank you, that works! Unfortunately, my real plots contain a few thousands of points, so I was wondering whether it's possible to avoid redrawing the plot and just do an update? Do you know how to do it; e.g. with the help of plotlyProxy()? I wasn't able to find an example of using plotlyProxy() in combination with plotly events.

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