Filtering leaflet map data in shiny

问题:

I'm having trouble setting up this shiny with a leaflet map. My original post had two questions and it was suggested I should start a new post to address my second issue: how do I get the map to show my updated data after I have filtered by speed; my table gets updated whether I change "speed" or the map bounds, but the leaflet map does not update points based on the speed filter input.

REPRODUCIBLE CODE

library(shiny)
library(magrittr)
library(leaflet)
library(DT)

ships <-
  read.csv(
    "https://raw.githubusercontent.com/Appsilon/crossfilter-demo/master/app/ships.csv"
  )

ui <- shinyUI(fluidPage(
  titlePanel("Filter"),
  sidebarLayout(
    sidebarPanel(width = 3,
                 numericInput(
                   "speed_f", label = h5("Ship's Speed"), value = 100
                 )),
    mainPanel(tabsetPanel(
      type = "tabs",
      tabPanel(
        "Leaflet",
        leafletOutput("leafletmap", width = "350px"),
        dataTableOutput("tbl")
      )
    ))
  )
))

server <- function(input, output) {
  in_bounding_box <- function(data, lat, long, bounds, speed) {
    data %>%
      dplyr::filter(
        lat > bounds$south &
          lat < bounds$north &
          long < bounds$east & long > bounds$west & 
          speed > input$speed_f
      )
  }

  output$leafletmap <- renderLeaflet({
    leaflet() %>%
      addProviderTiles("Esri.WorldImagery", group = "ESRI World Imagery") %>%
      addCircleMarkers(
        data = ships,
        ~ long ,
        ~ lat,
        popup =  ~ speed,
        radius = 5 ,
        stroke = FALSE,
        fillOpacity = 0.8,
        popupOptions = popupOptions(closeButton = FALSE)
      )
  })

  data_map <- reactive({
    if (is.null(input$leafletmap_bounds)) {
      ships
    } else {
      bounds <- input$leafletmap_bounds
      in_bounding_box(ships, lat, long, bounds, speed)
    }
  })

  output$tbl <- DT::renderDataTable({
    DT::datatable(
      data_map(),
      extensions = "Scroller",
      style = "bootstrap",
      class = "compact",
      width = "100%",
      options = list(
        deferRender = TRUE,
        scrollY = 300,
        scroller = TRUE,
        dom = 'tp'
      )
    )
  })


}

shinyApp(ui = ui, server = server)

UPDATE

Making the following change data = data_map() seems to work, with an exception:

  output$leafletmap <- renderLeaflet({
    leaflet() %>%
      addProviderTiles("Esri.WorldImagery", group = "ESRI World Imagery") %>%
      addCircleMarkers(
        data = data_map(), #### THIS LINE HAS CHANGED
        ~ long ,
        ~ lat,
        popup =  ~ speed,
        radius = 5 ,
        stroke = FALSE,
        fillOpacity = 0.8,
        popupOptions = popupOptions(closeButton = FALSE)
      )
  })

However, the leaflet map does not let me zoom out of the area defined by the filtered points. Is there a way around this?

回答1:

If you define a reactive just for the map data and use that within renderLeaflet it should allow you to then move out of the are defined. You don't need to change any of your other functions or reactives, just add the new reactive and make a couple of changes to renderLeaflet as below

map_data_react <- reactive({

    ships %>% dplyr::filter(speed > input$speed_f)

})


output$leafletmap <- renderLeaflet({

    ships_data <- map_data_react()  # Add this

    ships_data %>% leaflet() %>%
      addProviderTiles("Esri.WorldImagery", group = "ESRI World Imagery") %>%
      addCircleMarkers(
          ~ long ,  # Removed `data = data_map()`
          ~ lat,
          popup =  ~ speed,
          radius = 5 ,
          stroke = FALSE,
          fillOpacity = 0.8,
          popupOptions = popupOptions(closeButton = FALSE)
  )
})