R将等值线图与绘图坐标结合起来

Question

假设我有两个数据集，countries 和 cities:

set.seed(42)

countries <- data.frame(country = c("DEU", "FRA", "ITA", "POL"),
                      intensity = abs(rnorm(4)))

cities <- data.frame(city = c("Berlin", "Paris", "Roma", "Warszawa"),
                    longitude = c(13.408333, 2.351667, 12.483333, 21.033333),
                    latitude = c(52.518611, 48.856667, 41.883333, 52.216667))

countries 描述了国家级强度数据集。 cities是一个包含坐标的数据集。到目前为止，我已经使用 rworldmap 来绘制强度：

library(rworldmap)

map <- joinCountryData2Map(countries, joinCode = "ISO3", nameJoinColumn = "country")

mapCountryData(map, nameColumnToPlot = "intensity", mapRegion = "Europe")

如何根据城市数据集将国家级数据的等值线图与点叠加层相结合？

Answer 1

如果我没理解错的话，您可以使用 points:

向地图添加点

map <- joinCountryData2Map(countries, joinCode = "ISO3", nameJoinColumn = "country")
mapCountryData(map, nameColumnToPlot = "intensity", mapRegion = "Europe")
points(cities$longitude, cities$latitude, col = "black", cex = 1.5)

R将等值线图与绘图坐标结合起来

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