使用R将标题添加到Leaflet中的图层控制框 [英] Add title to layers control box in Leaflet using R

问题描述

我希望沿着可用图层"的行添加一个标题到图层控制框.

我的搜索仅使我得到一个相关结果:

• I am looking to add a title to the layer control box along the lines of "Available layers".

  My search has lead me to only one relevant result:

  • Exact same question using JS. Unclear how to translate

  My code:

  map %>% leaflet() %>%
    addProviderTiles(provider = "CartoDB") %>%
    # Group 1 Polygons
    addPolygons(data = map[!is.na(map$var),] ,weight =1, 
                color = ~g1_pal(g1), fillOpacity = .6,
                group = "Group 1",
                # add labels
                label = ~labels,
                # highlight polygons on hover
                highlight = highlightOptions(weight = 5, color = "white",
                                             bringToFront = TRUE)) %>%
    # Group 2
    addPolygons(data = map[!is.na(map$var2),], weight =1, 
                color = ~g2_pal(g2), fillOpacity = .6,
                group = "Group 2",
                # add labels that display mean income
                label = ~labels2,
                # highlight polygons on hover
                highlight = highlightOptions(weight = 5, color = "white",
                                             bringToFront = TRUE)) %>%
    addLayersControl(baseGroups = c("Group 1", "Group 2"), 
                     options = layersControlOptions(collapsed=F, 
                                                    # Series of attempts 
                                                    label = "Layers",
                                                    title = "Layers"))
  

  Neither of these attempts worked. It does appear from the link above that there is an attribute that can be accessed but I am unsure of how to reference it.

  解决方案

  The best way to do this (that I'm aware of) is to use htmlwidgets::onRender to add your Javascript to the map upon rendering. This is described in the last section at the bottom of the last page in the docs, so it's easy to miss!

  Here's an example that implements the Javascript that Saurabh Yadav described in his answer to the question you linked. You simply add the Javascript function to the end of the leaflet() piped call:

  library(leaflet)
  
  leaflet() %>%
      addTiles() %>%
      addLayersControl(
          overlayGroups = "MyImaginaryLine",
          options = layersControlOptions(collapsed = FALSE)) %>%
      htmlwidgets::onRender("
          function() {
              $('.leaflet-control-layers-overlays').prepend('<label style=\"text-align:center\">My Epic Title</label>');
          }
      ")
  

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