Feature: Add points and edges through a proxy

[janithwanni]

Depends on: #121
Changes:

• Adds a proxy that can be accessed through the R function display_scatter_proxy
• Adds functions add_points and add_edges to add additional points and edges using the proxy returned by the above function
• These points and edges remain separate and independent of the existing dataset.

[janithwanni]

Hi @casperhart,

This PR provides the functionality to add points and edges to an existing detour instance through a proxy object (similar to the approach taken by leaflet and other Javascript libraries). The Shiny app in the demo/shiny_detourr/add_points_edges.R file contains an example of adding a box around a given point and demonstrates how to use the proxy within Shiny modules.

library(shiny)
library(detourr)

dataset <- tourr::flea |>
  dplyr::mutate(id = dplyr::row_number())

create_fake_box <- function(datum) {
  # expected tibble needs to have two rows with ncols(datum) + 1 columns
  box_dist <- rnorm(1, mean = 3)
  bounds_list <- rbind(datum + box_dist, datum - box_dist) |>
    as.list()
  do.call(tidyr::expand_grid, bounds_list)
}

main_ui <- function(id) {
  ns <- NS(id)
  fluidPage(
    column(6,
      displayScatter2dOutput(
        ns("detourr_out"), width = "100%", height = "400px"
      ),
      textOutput(ns("detour_click_output"))
    ),
    column(6,
      h1("Adding points and edges to detourr through Shiny"),
      p(
        "In this demonstration,",
        "clicking on points on the detourr instance to the left",
        "adds a box around the point.",
        "Click on the play button to view the box in different projections"
      )
    )
  )
}

main_server <- function(id) {
  moduleServer(id, function(input, output, session){
    output$detourr_out <- shinyRenderDisplayScatter2d({
      detour(dataset,
        tour_aes(projection = -c(id, species), colour = species, label = id)
      ) |>
        tour_path(grand_tour(2), fps = 60) |>
        show_scatter(
          alpha = 0.7,
          axes = TRUE
        )
    })

    output$detour_click_output <- renderText({
      input$detourr_out_detour_click
    })

    observeEvent(input$detourr_out_detour_click, {
      req(
        !is.null(input$detourr_out_detour_click),
        input$detourr_out_detour_click != -1
      )
      data_to_send <- dataset |>
        dplyr::select(-species) |>
        dplyr::filter(id == input$detourr_out_detour_click) |>
        dplyr::select(-id)

      box_to_send <- data_to_send |> create_fake_box()

      cube_box <- geozoo::cube.iterate(p = ncol(data_to_send))

      display_scatter_proxy(session$ns("detourr_out")) |>
        add_points(
          box_to_send,
          .data = dataset |> dplyr::select(-c(id, species))
        ) |>
        add_edges(
          edge_list = cube_box$edges
        )
    })

  })
}

ui <- function() {
  main_ui("main")
}

server <- function(input, output, session) {
  main_server("main")
}

shinyApp(ui, server, options = list(port = 5534))

[janithwanni]

cli package to provide alerts and errors

[janithwanni]

This approach had to be implemented because the tourr package does scaling internally and therefore we need to scale the points that are given to make sure that they fit in the exact required location.

[janithwanni]

This might be catching other errors apart from the widget not being found but for the time being I'm leaving it as it is, because that is the most likely candidate of throwing errors here.

[casperhart]

In what scenarios would the widget not be found?

[janithwanni]

I implemented it such that only one set of additional points can be added at a given time. @casperhart, if you have suggestions for a better implementation of this, I'm open to implementing it.

[janithwanni]

Extended addEdgeSegments function to enable arrays outside of the internal class variable.

[janithwanni]

Simple tests to begin with at the moment. But can be extended to more extensive tests once the single widget setup is complete.

[casperhart]

Something isn't working properly for me. I have run the demo, but the box is much bigger than in the screen capture you added:

Also, if I zoom right in and then click a point, the new points that are added are much bigger than the existing points:

And do you have any other examples of how this might be used? Not code examples, just so I can better understand what the feature is for

[casperhart]

In what scenarios would the widget not be found?