Question

我有一个闪亮的应用程序，用户可以通过DrawToolbar在传单地图上创建新点。每次设置新标记时，坐标都会添加到data.frame中。我想将这些坐标显示为新添加标记的弹出窗口。这可能不会失去拖动或移除新标记的可能性吗？

library(shiny)
library(leaflet)
library(leaflet.extras)

ui <- fluidPage(
  leafletOutput("map")
)

data <- data.frame(lat = c(), lon = c())

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

  output$map <- renderLeaflet({
    leaflet() %>% addTiles() %>% 
      addDrawToolbar(
        targetGroup = "new_points",
        polylineOptions = FALSE,
        polygonOptions = FALSE,
        rectangleOptions = FALSE,
        circleOptions = FALSE,
        editOptions = editToolbarOptions(selectedPathOptions = selectedPathOptions()))
  })

  observeEvent(input$map_draw_new_feature, {
    click_lat <- input$map_draw_new_feature$geometry$coordinates[[2]]
    click_lon <- input$map_draw_new_feature$geometry$coordinates[[1]]
    data <- rbind(data, cbind(click_lat, click_lon))
    print(data)
  })

}


shinyApp(ui, server)

Answer 1

您可以使用reactiveValues代替全局变量来存储新标记，每次添加时都会重新绘制地图（使用弹出窗口添加所有标记）：

library(shiny)
library(leaflet)
library(leaflet.extras)

ui <- fluidPage(
  leafletOutput("map")
)

server <- function(input, output, session) {
  data <- reactiveValues(lat = NULL, lon = NULL)
  output$map <- renderLeaflet({
    # Get setView parameters
    new_zoom <- 2
    if(!is.null(input$map_zoom)) new_zoom <- input$map_zoom
    new_lat <- 0
    if(!is.null(input$map_center$lat)) new_lat <- input$map_center$lat
    new_lon <- 0
    if(!is.null(input$map_center$lng)) new_lon <- input$map_center$lng

    leaflet() %>% addTiles() %>% 
      setView(new_lon,new_lat,zoom = new_zoom) %>% 
      addDrawToolbar(
        targetGroup = "new_points",
        polylineOptions = FALSE,
        polygonOptions = FALSE,
        rectangleOptions = FALSE,
        circleOptions = FALSE,
        editOptions = editToolbarOptions(
          selectedPathOptions = selectedPathOptions()))-> map

    if (!is.null(data$lat)) {
       addMarkers(map, lng=data$lon, lat=data$lat, 
          popup=paste("lat=", data$lat, ", lon=", data$lon))}
    else map
  })

  observeEvent(input$map_draw_new_feature, {
    click_lat <- input$map_draw_new_feature$geometry$coordinates[[2]]
    click_lon <- input$map_draw_new_feature$geometry$coordinates[[1]]
    data$lat <- c(data$lat,click_lat)
    data$lon <- c(data$lon,click_lon)
  })
}

shinyApp(ui, server)

请注意setView调用以避免缩放到您添加的第一个标记

将弹出窗口添加到DrawToolbar添加的标记中

1 个答案: