r - ggplot - 在 map 顶部创建一个边界叠加层

Question

因此，我正在尝试根据自定义变量创建带有边界的佛罗里达县级 map 。我在此处包含了我正在尝试创建的旧版 map

从本质上讲，该 map 显示了佛罗里达州各县的区域分割，媒体市场用粗体黑线边框勾勒。我能够很容易地绘制区域。我希望添加的是在媒体市场变量“MMarket”定义的区域之外的更粗的黑线边框，类似于上面显示的 map 。填充变量将为 Region，媒体市场边界轮廓将使用 MMarket 定义。以下是读取和强化数据的方式:

#read in data
fl_data <- read_csv("Data for Mapping.csv")

#read in shapefiles
flcounties1 <- readOGR(dsn =".",layer = "Florida Counties")

#Fortify based on county name
counties.points <- fortify(flcounties1, region = "NAME")
counties.points$id <- toupper(counties.points$id)

#Merge plotting data and geospatial dataframe 
merged <- merge(counties.points, merged_data, by.x="id", by.y="County", all.x=TRUE)

fl_data 对象包含要映射的数据(包括媒体市场变量)，并将 shapefile 数据读入 flcounties1 。这是我正在使用的合并数据框的示例:

 head(merged %>% select(id:group, Region, MMarket))
       id      long      lat order  hole piece     group    Region     MMarket
1 ALACHUA -82.65855 29.83014     1 FALSE     1 Alachua.1 Panhandle Gainesville
2 ALACHUA -82.65551 29.82969     2 FALSE     1 Alachua.1 Panhandle Gainesville
3 ALACHUA -82.65456 29.82905     3 FALSE     1 Alachua.1 Panhandle Gainesville
4 ALACHUA -82.65367 29.82694     4 FALSE     1 Alachua.1 Panhandle Gainesville
5 ALACHUA -82.65211 29.82563     5 FALSE     1 Alachua.1 Panhandle Gainesville
6 ALACHUA -82.64915 29.82648     6 FALSE     1 Alachua.1 Panhandle Gainesville

我可以使用以下代码很容易地获得区域变量的 map :

ggplot() +
  # county polygons
  geom_polygon(data = merged, aes(fill = Region,
                                  x = long,
                                  y = lat,
                                  group = group)) +
  # county outline
  geom_path(data = merged, aes(x = long, y = lat, group = group), 
            color = "black", size = 1) +
  coord_equal() +
  # add the previously defined basic theme
  theme_map() +
  labs(x = NULL, y = NULL, 
       title = "Florida: Regions by County") +
  scale_fill_brewer(palette = "Set3",
                    direction = 1,
                    drop = FALSE,
                    guide = guide_legend(direction = "vertical",
                                         title.hjust = 0,
                                         title.vjust = 1,
                                         barheight = 30,
                                         label.position = "right",
                                         reverse = T,
                                         label.hjust = 0))

Answer 1

如果您想进入 sf，这里有一个快速示例与 ggplot2::geom_sf .由于我没有您的 shapefile，我只是使用 tigris 下载康涅狄格州的县分割 shapefile ，然后将其转换为简单的 features 对象。

更新说明:随着 sf 的更新版本，一些事情似乎发生了变化。 ，这样你现在应该只用 summarise 将城镇合并为县。 .

# download the shapefile I'll work with
library(dplyr)
library(ggplot2)
library(sf)

ct_sf <- tigris::county_subdivisions(state = "09", cb = T, class = "sf")

如果我想按原样绘制这些城镇，我可以使用 ggplot和 geom_sf :

ggplot(ct_sf) +
  geom_sf(fill = "gray95", color = "gray50", size = 0.5) +
  # these 2 lines just clean up appearance
  theme_void() +
  coord_sf(ndiscr = F)

分组和调用 summarise没有功能为您提供了几个功能的结合。我将根据县 FIPS 代码(即 COUNTYFP)来联合城镇。柱子。 sf函数适合 dplyr管道，这太棒了。

所以这:

ct_sf %>% 
    group_by(COUNTYFP) %>% 
    summarise()

会给我一个 sf对象所有城镇都已合并到他们的县。我可以将这两者结合起来得到第一个城镇的 map geom_sf层，并在第二层中即时对县进行联合:

ggplot(ct_sf) +
  geom_sf(fill = "gray95", color = "gray50", size = 0.5) +
  geom_sf(fill = "transparent", color = "gray20", size = 1, 
          data = . %>% group_by(COUNTYFP) %>% summarise()) +
  theme_void() +
  coord_sf(ndiscr = F)

没有了 fortify !