俄罗斯的阴谋一分为二

Question

我试图从 shp 文件中绘制俄罗斯，但俄罗斯总是分为两部分。我怎样才能让俄罗斯一气呵成？

我尝试了几个 shp 文件，例如 http://www.naturalearthdata.com/downloads/10m-culture-vectors/ Admin 1 – States, Provinces ；下载无大湖 (14.11 MB) 3.0.0 版

 shp <- readOGR("ne_10m_admin_1_states_provinces_lakes.shp")

子集到俄罗斯

names(shp)
rus <- shp[shp$admin == "Russia" , ]

x11()
plot(rus)

Answer 1

由于要绘制它，因此可以将 shapefile 强化到数据框，修改 -180 区域中的经度坐标，并将结果绘制在ggplot：

library(rgdal); library(ggplot2)

# read in the shapefile & subset to Russia
shp <- readOGR(dsn = "ne_10m", layer = "ne_10m_admin_1_states_provinces_lakes")
rus <- shp[shp$admin == "Russia", ]

# fortify to data frame & modify longitude coordinates in the -180 region.
rus.fortify <- fortify(rus) %>%
  mutate(long = ifelse(long < -100, long + 180*2, long))

# plot to verify
ggplot(rus.fortify,
       aes(x = long, y = lat, group = group)) +
  geom_polygon(fill = "white", col = "black") +
  coord_map() #default projection is mercator

我还刚刚从这篇文章中了解到，您可以指定不同的投影系统。鉴于俄罗斯有多大，这应该是相关的：

ggplot(rus.fortify,
       aes(x = long, y = lat, group = group)) +
  geom_polygon(fill = "white", col = "black") +
  coord_map("azequalarea")