世界地图 - 将国家的一半映射到不同的颜色

Question

我在这里使用这个例子进行讨论: ggplot map with l

library(rgdal)
library(ggplot2)
library(maptools)

# Data from http://thematicmapping.org/downloads/world_borders.php.
# Direct link: http://thematicmapping.org/downloads/TM_WORLD_BORDERS_SIMPL-0.3.zip
# Unpack and put the files in a dir 'data'

gpclibPermit()
world.map <- readOGR(dsn="data", layer="TM_WORLD_BORDERS_SIMPL-0.3")
world.ggmap <- fortify(world.map, region = "NAME")

n <- length(unique(world.ggmap$id))
df <- data.frame(id = unique(world.ggmap$id),
                 growth = 4*runif(n),
                 category = factor(sample(1:5, n, replace=T)))

## noise
df[c(sample(1:100,40)),c("growth", "category")] <- NA


ggplot(df, aes(map_id = id)) +
     geom_map(aes(fill = growth, color = category), map =world.ggmap) +
     expand_limits(x = world.ggmap$long, y = world.ggmap$lat) +
     scale_fill_gradient(low = "red", high = "blue", guide = "colorbar")

给出以下结果:

我想将一个变量映射到一个国家的左"一半",将一个不同的变量映射到该国的右半部分.我把"一半"放在引号中因为它没有明确定义(或者至少我没有明确定义它).Ian Fellows的答案可能有所帮助(这为获得质心提供了一种简单的方法).我希望有一些东西能让我aes(left_half_color = growth, right_half_color = category)在这个例子中做到.如果不同的话,我也会对上半部分和下半部分感兴趣.

如果可能的话,我还想将两半的个体质心映射到某个东西.

Answer 1

这是一个没有ggplot它的解决方案,plot而是依赖于函数.rgeos除了OP中的代码之外,它还需要包:

编辑现在减少10%的视觉疼痛

编辑2现在有了质心的东和西半

library(rgeos)
library(RColorBrewer)

# Get centroids of countries
theCents <- coordinates(world.map)

# extract the polygons objects
pl <- slot(world.map, "polygons")

# Create square polygons that cover the east (left) half of each country's bbox
lpolys <- lapply(seq_along(pl), function(x) {
  lbox <- bbox(pl[[x]])
  lbox[1, 2] <- theCents[x, 1]
  Polygon(expand.grid(lbox[1,], lbox[2,])[c(1,3,4,2,1),])
})

# Slightly different data handling
wmRN <- row.names(world.map)

n <- nrow(world.map@data)
world.map@data[, c("growth", "category")] <- list(growth = 4*runif(n),
                 category = factor(sample(1:5, n, replace=TRUE)))

# Determine the intersection of each country with the respective "left polygon"
lPolys <- lapply(seq_along(lpolys), function(x) {
  curLPol <- SpatialPolygons(list(Polygons(lpolys[x], wmRN[x])),
    proj4string=CRS(proj4string(world.map)))
  curPl <- SpatialPolygons(pl[x], proj4string=CRS(proj4string(world.map)))
  theInt <- gIntersection(curLPol, curPl, id = wmRN[x])
  theInt
})

# Create a SpatialPolygonDataFrame of the intersections
lSPDF <- SpatialPolygonsDataFrame(SpatialPolygons(unlist(lapply(lPolys,
  slot, "polygons")), proj4string = CRS(proj4string(world.map))),
  world.map@data)

##########
## EDIT ##
##########
# Create a slightly less harsh color set
s_growth <- scale(world.map@data$growth,
  center = min(world.map@data$growth), scale = max(world.map@data$growth))
growthRGB <- colorRamp(c("red", "blue"))(s_growth)
growthCols <- apply(growthRGB, 1, function(x) rgb(x[1], x[2], x[3],
  maxColorValue = 255))
catCols <- brewer.pal(nlevels(lSPDF@data$category), "Pastel2")

# and plot
plot(world.map, col = growthCols, bg = "grey90")

plot(lSPDF, col = catCols[lSPDF@data$category], add = TRUE)

也许有人可以提出一个很好的解决方案ggplot2.但是,基于对单个图形的多个填充比例的问题的答案("你不能"),如果ggplot2没有分面,解决方案似乎不太可能(这可能是一个很好的方法,如上面的评论中所建议的).

编辑重新:将两半的质心映射到某个东西:东部("左")半部的质心可以通过以下方式获得:

coordinates(lSPDF)

可以通过rSPDF以类似方式创建对象来获得西方("右")一半的那些:

# Create square polygons that cover west (right) half of each country's bbox
rpolys <- lapply(seq_along(pl), function(x) {
  rbox <- bbox(pl[[x]])
  rbox[1, 1] <- theCents[x, 1]
  Polygon(expand.grid(rbox[1,], rbox[2,])[c(1,3,4,2,1),])
})

# Determine the intersection of each country with the respective "right polygon"
rPolys <- lapply(seq_along(rpolys), function(x) {
  curRPol <- SpatialPolygons(list(Polygons(rpolys[x], wmRN[x])),
    proj4string=CRS(proj4string(world.map)))
  curPl <- SpatialPolygons(pl[x], proj4string=CRS(proj4string(world.map)))
  theInt <- gIntersection(curRPol, curPl, id = wmRN[x])
  theInt
})

# Create a SpatialPolygonDataFrame of the western (right) intersections
rSPDF <- SpatialPolygonsDataFrame(SpatialPolygons(unlist(lapply(rPolys,
  slot, "polygons")), proj4string = CRS(proj4string(world.map))),
  world.map@data)

然后可以根据lSPDF或的质心在地图上绘制信息rSPDF:

points(coordinates(rSPDF), col = factor(rSPDF@data$REGION))
# or
text(coordinates(lSPDF), labels = lSPDF@data$FIPS, cex = .7)