将数据与SpatialPolygonsDataFrame对象列表进行匹配，以便在传单中运行一张合唱图

Question

我教自己如何在R中使用映射工具，在这种情况下，我希望根据以下mydata数据框架的结果，在各自的区域级别建立各国的副图。

请注意，我实际上是在30个国家运行这个项目。我只是为了可复制的目的而限制在这里的两个国家。另外，请注意，getData函数将从GADM.org网站下载。

library(sp)
library(raster)
library(tidyverse)
library(leaflet)

France_map <- getData(name = "GADM", country = "FRA", level = 1)
Germany_map <- getData(name = "GADM", country = "DEU", level = 1)

all_maps <- list(France_map, Germany_map)

mydata <- dput(structure(list(cntry = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 
  1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 
  2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L), .Label = c("Germany", "France"), 
  class = "factor"), region_name = structure(1:37, .Label = c("Baden-Württemberg", 
  "Bayern", "Berlin", "Brandenburg", "Bremen", "Hamburg", "Hessen", "Mecklenburg-Vorpommern", 
  "Niedersachsen", "Nordrhein-Westfalen", "Rheinland-Pfalz", "Saarland", "Sachsen", 
  "Sachsen-Anhalt", "Schleswig-Holstein", "Thüringen", "Île-de-France", "Champagne-Ardenne", 
  "Picardie", "Haute-Normandie", "Centre", "Basse-Normandie", "Bourgogne", 
  "Nord-Pas-de-Calais", "Lorraine", "Alsace", "Franche-Comté", "Pays de la Loire", 
  "Bretagne", "Poitou-Charentes", "Aquitaine", "Midi-Pyrénées", "Limousin", 
  "Rhône-Alpes", "Auvergne", "Languedoc-Roussillon", "Provence-Alpes-Côte d'Azur"), 
  class = "factor"), prop = c(0.0771812080536913, 0.0808625336927224, 0.154200131820421, 
  0.143712574850299, 0.125, 0.1875, 0.160220994475138, 0.201612903225806, 
  0.149122807017544, 0.140562248995984, 0.111111111111111, 0.130434782608696, 
  0.162454873646209, 0.141891891891892, 0.164835164835165, 0.0810810810810811, 
  0.320361006883289, 0.173944002182893, 0.267984998166555, 0.145696294975402, 
  0.307927600677265, 0.218154962499145, 0.249630808322935, 0.276741747762545, 
  0.0959323496890737, 0.144213110146746, 0.0929990840802643, 0.190088309954592, 
  0.159029556704208, 0.204186267910012, 0.26199124557682, 0.171309738332821, 
  0.125707503945437, 0.241559205433323, 0.170811734710593, 0.275876128675216, 
  0.205483749159249)), .Names = c("cntry", "region_name", "prop"), class = c("tbl_df", 
  "tbl", "data.frame"), row.names = c(NA, -37L)))

现在我要做的是将来自prop变量mydata的结果显示到一个choropleth地图上，使用如下所示：

leaflet() %>%
  addPolygons()

我的绊脚石是，如何让R将prop变量中的结果与SPDF文件中的相应区域匹配以运行choropleth映射？

Answer 1

我把Germany_map和France_map组合在一起，这样我就可以同时画多边形了。然后，我为prop创建了颜色。使用addPolygons()时，可以指定fillColor = ~mypal(mydata$prop)。道具值不必停留在多边形数据中。同样，您可以在values = mydata$prop中指定addLegend()。您可以看到下面的结果是屏幕截图。

library(sp)
library(raster)
library(maptools)
library(leaflet)

# Combine German and French polygons
mymap <- rbind(Germany_map, France_map, makeUniqueIDs = TRUE)

### Create colors for prop
mypal <- colorNumeric(palette = "Reds", domain = mydata$prop)


leaflet() %>% 
addProviderTiles("OpenStreetMap.Mapnik") %>%
setView(lat = 49.2402, lng = 6.9969, zoom = 6) %>%
addPolygons(data = mymap,
            stroke = FALSE, smoothFactor = 0.2, fillOpacity = 0.5,
            fillColor = ~mypal(mydata$prop),
            popup = paste("Region: ", mymap$NAME_1, "<br>",
                          "Prop: ", mydata$prop, "<br>")) %>%
addLegend(position = "bottomright", pal = mypal, values = mydata$prop,
          title = "Prop",
          opacity = 0.5)

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