Interactivity within the same graph - ggvis

Question

I have the following ggvis with shiny code, which produces 2 graphs with the mtcars data set that comes with R. In the first graph if I double click on a point, all the points with the same number of gear (mtcars$gear) within the 2nd graph turns into red. Motor cars can have 3, 4 or 5 gears. So, if I click on a point in the 1st graph, which has 3 gears, all the cars which have 3 gears turn into red points in the 2nd graph.

This is the server.R code-

library(ggvis)
library(dplyr)

mtcars$id <- seq_len(nrow(mtcars))


shinyServer(function(input, output, session) {

  lb <- linked_brush(keys = mtcars$id, "red")

  mtcars %>%
    ggvis(~mpg, ~wt) %>%
    layer_points(fill := lb$fill, fill.brush := "red") %>%
    lb$input() %>%
    set_options(width = 300, height = 300) %>%
    bind_shiny("plot1") # Very important!

  # A subset of mtcars, of only the selected points
  selected <- lb$selected
  mtcars_selected <- reactive({
    mtcars[selected(), ]
  })

  mtcars_selected1 <- reactive({
    print(mtcars[mtcars$gear == mtcars[selected(), ]$gear, ])
  })

  vis <- reactive({ 
    mtcars %>%
    ggvis(~mpg, ~wt) %>%
    layer_points()  %>%
    add_data(mtcars_selected1) %>%
    layer_points(fill := "#dd3333") %>%
    set_options(width = 300, height = 300)
  })

  vis %>% bind_shiny("plot2")
})

This is the ui.R code -

library(ggvis)

shinyUI(bootstrapPage(
  ggvisOutput("plot1"),
  ggvisOutput("plot2")
))

My question is, is it possible to do this in the same graph ? That is I want to click on a point and all the points with the same number of gears will turn into red in the same graph. I have googled it for a long time and I cant seem to find any direction. Any help will be greatly appreciated.

Answer 1

You can add another layer in the first plot that will add the points that have the same gears as the selected points:

  mtcars %>%
    ggvis(~mpg, ~wt) %>%
    layer_points(fill := lb$fill, fill.brush := "red") %>%
    lb$input() %>%
    set_options(width = 300, height = 300) %>%
    #the next line will add red points that have the same gear as the ones selected
    layer_points(fill := "red", data = reactive(mtcars[mtcars$gear %in% mtcars[lb$selected(),]$gear,])) %>%
    bind_shiny("plot1") # Very important!