用ggplot填充voronoi多边形

Question

我想用基于变量的颜色填充voronoi多边形(在我的情况下为z).这是代码:

library(rgdal)
library(deldir)
library(dplyr)
library(ggplot2)
library(UScensus2010)

x<-c(0,55,105,165,270,65,130,155,155,225,250,295,
     30,100,110,135,160,190,230,300,30,70,105,170,
     210,245,300,0,85,175,300,15,60,90,90,140,210,
     260,270,295,5,55,55,90,100,140,190,255,285,270)
y<-c(305,310,305,310,310,260,255,265,285,280,250,
     260,210,240,225,225,225,230,210,215,160,190,
     190,175,160,160,170,120,135,115,110,85,90,90,
     55,55,90,85,50,50,25,30,5,35,15,0,40,20,5,150)
z<-c(870,793,755,690,800,800,730,728,710,780,804,
     855,813,762,765,740,765,760,790,820,855,812,
     773,812,827,805,840,890,820,873,875,873,865,
     841,862,908,855,850,882,910,940,915,890,880,
     870,880,960,890,860,830)
dati<-data.frame(x,y,z)

vor_pts <- SpatialPointsDataFrame(cbind(dati$x,dati$y),dati, match.ID=TRUE)

SPointsDF_to_voronoi_SPolysDF <- function(sp) {

  # tile.list extracts the polygon data from the deldir computation
  vor_desc <- tile.list(deldir(sp@coords[,1], sp@coords[,2]))

  lapply(1:(length(vor_desc)), function(i) {

    # tile.list gets us the points for the polygons but we
    # still have to close them, hence the need for the rbind
    tmp <- cbind(vor_desc[[i]]$x, vor_desc[[i]]$y)
    tmp <- rbind(tmp, tmp[1,])

    # now we can make the Polygon(s)
    Polygons(list(Polygon(tmp)), ID=i)

  }) -> vor_polygons

  # hopefully the caller passed in good metadata!
  sp_dat <- sp@data

  # this way the IDs _should_ match up w/the data & voronoi polys
  rownames(sp_dat) <- sapply(slot(SpatialPolygons(vor_polygons),
                                  'polygons'),
                             slot, 'ID')

  SpatialPolygonsDataFrame(SpatialPolygons(vor_polygons),
                           data=sp_dat)

}

vor <- SPointsDF_to_voronoi_SPolysDF(vor_pts)

vor_df <- fortify(vor)


ggplot() +
geom_point(data = dati, aes(x, y), shape=21,
           color = "white", fill = "steel blue") +
geom_map(data = vor_df, map = vor_df, aes(x = long, y = lat, map_id = id),
         color = "#a5a5a5", fill = "#FFFFFF00", size = 0.25)

现在我有这个图像:

我希望每个多边形都应该根据变量z的值映射到颜色标度...我该怎么做？谢谢!!!

Answer 1

据我所知,您不能使用与数据问题本身长度不同的向量(在本例中为行数vor_df)来指定填充颜色.但是,如果我假设每个元素z都应用于形状的id vor_df,你可以这样做;

ggplot() +
  geom_map(data=vor_df, map=vor_df,aes(x=long, y=lat, map_id=id, fill = id), size=0.25) +
  geom_path(data=vor_df,aes(x=long, y=lat, map=id)) +
  geom_point(data = dati, aes(x, y),shape=21, color="white", fill="steelblue")

这会将id列映射到每个多边形作为颜色.z如果你需要在图例中或任何其他数量的东西中添加一个单独的列来为每个id添加一个值就足够了.

尽管如此,这都假设每个都id与矢量中的数字直接相关z.