experiments/crosstalk_shiny.R

In r-spatial/mapedit: Interactive Editing of Spatial Data in R

# devtools::install_github("rstudio/crosstalk")
# devtools::install_github("rstudio/leaflet")

library(crosstalk)
library(leaflet)
library(shiny)
library(dplyr)

rand_lng = function(n = 10) rnorm(n, -93.65, .01)
rand_lat = function(n = 10) rnorm(n, 42.0285, .01)

pts <- SharedData$new(
  data.frame(
    id = 1:10,
    lng = rand_lng(),
    lat = rand_lat()
  ),
  key = ~id,
  group = "grp1"
)


ui <- fluidPage(
  fluidRow(
    column(2, filter_select(id="filterselect", label="Points", sharedData=pts, group=~id)),
    column(6, leafletOutput("leaflet1"))
  ),
  h4("Selected points"),
  verbatimTextOutput("selectedpoints")
)

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

  pts <- SharedData$new(
    data.frame(
      id = 1:10,
      lng = rand_lng(),
      lat = rand_lat()
    ),
    key = ~id,
    group = "grp1"
  )


  lf <- leaflet(pts) %>%
    addTiles() %>%
    addMarkers()

  not_rendered <- TRUE

  output$leaflet1 <- renderLeaflet({
    if(req(not_rendered,cancelOutput=TRUE)) {
      not_rendered <- FALSE
      lf
    }
  })

  output$selectedpoints <- renderPrint({
    df <- pts$data(withSelection = TRUE)
    cat(nrow(df), "observation(s) selected\n\n")
    str(dplyr::glimpse(df))
  })
}

shinyApp(ui, server)