R传单是在覆盖层的顶部绘制基础层

我遇到了一个关于R的传单的问题：当我更改基础层（多边形）时，覆盖层被推到基础层后面。根据我对传单帮助文件的阅读，覆盖层的z索引应始终高于基础层，并且应保持在顶部

例如：

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多边形层的z索引应始终高于平铺层。“层”控件使用此术语是因为基本组是基本（平铺）层，而覆盖组是覆盖（多边形）层

您可以使用一点JavaScript来解决这个问题，请参见添加到管道中的onRender阶段（对于给定的贴图对象，您只需执行一次）：

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多边形层的z索引应始终高于平铺层。“层”控件使用此术语是因为基本组是基本（平铺）层，而覆盖组是覆盖（多边形）层

您可以使用一点JavaScript来解决这个问题，请参见添加到管道中的onRender阶段（对于给定的贴图对象，您只需执行一次）：

require(acs)
require(tigris)
require(leaflet)
require(tidyverse)

leaflet(data = counties(state = "UT")) %>% 
  addPolygons(color = "red", fillColor = "orange", group = "base1", fillOpacity = 1) %>% 
  addPolygons(color = "pink", fillColor = "purple", group = "base2", fillOpacity = 1) %>% 
  addPolygons(color = "yellow", fillColor = "green", group = "overlay", fillOpacity = 1) %>% 
  addLayersControl(baseGroups = c("base1", "base2"), options = layersControlOptions(collapsed = F), overlayGroups = "overlay")

leaflet(data = counties(state = "UT")) %>% 
  addPolygons(color = "red", fillColor = "orange", group = "base1", fillOpacity = 1) %>% 
  addPolygons(color = "pink", fillColor = "purple", group = "base2", fillOpacity = 1) %>% 
  addPolygons(color = "yellow", fillColor = "green", group = "overlay", fillOpacity = 0.5) %>% 
  addLayersControl(baseGroups = c("base1", "base2"), options = layersControlOptions(collapsed = F), overlayGroups = "overlay") %>%
  htmlwidgets::onRender("
    function(el, x) {
      this.on('baselayerchange', function(e) {
        e.layer.bringToBack();
      })
    }
  ")