【发布时间】：2013-04-08 08:04:09
【问题描述】：
我想在 R 中创建一张欧洲地图来绘制我的一些数据。我修改了下面的代码（取自：http://www.r-bloggers.com/provincial-map-using-gadm/）给我一张欧洲地图。一切都很好，只是波罗的海沿岸的俄罗斯碎片消失了。
我如何提取俄罗斯多边形的那一部分以维护真实的欧洲地图？
library(sp)
library(raster)
## Download Map of the World ##
WorldMap <- getData('countries')
## Subset world map to European countries ##
EuropeMap <- (WorldMap[WorldMap$CONTINENT=="Europe" & WorldMap$COUNTRY != "Russia",])
## Plot map ##
plot(EuropeMap, bg = "dodgerblue", axes = T)
plot(EuropeMap, lwd = 10, border = "skyblue", add = T)
plot(EuropeMap, col ="green4", add = T)
grid()
box()
invisible(text(getSpPPolygonsLabptSlots(EuropeMap), labels = as.character(EuropeMap$COUNTRY), cex = 0.5, col = "white", font = 2))
mtext(side = 3, line = 1, "Map of Europe", cex = 2)
mtext(side = 1, "Longtiude", line = 2.5, cex = 1.1)
mtext(side = 2, "Latitude", line = 2.5, cex = 1.1)
text(40,30, "Projection: Geographic\nCoordinate System: WGS 1984\nData Source: GADM.org\nCreated by: Keith Larson", adj = c(0,0), cex = 0.7, col = "grey20")
text(-35, 75, "Calopteryx splendens", col="white", font=3, cex=1.5)
【问题讨论】：
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如果您可以提取“俄罗斯”多边形数据，您可能能够找到它与最终地图边界坐标的交点，并绘制新的“长条”多边形。或者，绘制所有“俄罗斯”并用白色矩形覆盖地图的外部。