Question

我愿绘制一份显示国家边界、各县边界和地形背景的堪萨斯州地图。为此,我使用以下图书馆:<代码>ggmap和>>mapdata。

library(ggmap)
library(ggthemes)
library(dplyr)
library(mapdata)

ks_state_map_df <- map_data("state", region="kansas")
ks_counties_map_df <- map_data("county") %>% filter(region=="kansas")
ks_cities_map_df <- us.cities %>% filter(country.etc=="KS")
ks_cities_map_df$name <- gsub(" KS","", ks_cities_map_df$name)
KS_area <- c(left=-102.051744, right=-94.588413, bottom=36.993016, top=40.003162)
KS_map <- get_stadiamap(bbox=KS_area, maptype= outdoors )

ggmap(KS_map) +
  theme_map() +
  geom_polygon(data=ks_state_map_df, mapping=aes(x=long, y=lat, group=group), color="black", fill=NA) + 
  geom_polygon(data=ks_counties_map_df,  mapping=aes(x=long, y=lat), color="gray", fill=NA) + 
  geom_point(data=ks_cities_map_df, mapping=aes(x=long, y=lat)) +
  geom_text(data=ks_cities_map_df, mapping=aes(x=long, y=lat, label=name), hjust=0, nudge_x=0.1)

However, it seems that my above code attempt does not render the polygons correctly (something to do with the group attribute, I believe). How do I need to fix my code?

Edit 1: The terrain map areas should be increased to: KS_area <- c(left=-102.2, right=-94.4, bottom=37.2, top=40.2)

Answer 1

页: 1

我夸大了四个地段的界线,只是要强调什么是“新的”。

ggmap(KS_map) +
  theme_map() +
  geom_polygon(data=ks_state_map_df, mapping=aes(x=long, y=lat, group=group), color="black", fill=NA, linewidth=10) + 
  geom_polygon(data=ks_counties_map_df,  mapping=aes(x=long, y=lat, group=group), color="gray", fill=NA, linewidth=10) + 
  geom_point(data=ks_cities_map_df, mapping=aes(x=long, y=lat), size=10) +
  geom_text(data=ks_cities_map_df, mapping=aes(x=long, y=lat, label=name), hjust=0, nudge_x=0.1, size=10)

我并不完全相信<代码>ks_state_map_df,它造成两个黑色方言。

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