结合 Voronoi 多边形和地图

Question

我想将 Voronoi 多边形与地图结合起来，以便稍后将其用于空间分析。我有许多点和要组合的 shapefile，然后保存为 shapefile/空间多边形。要获得 voronoi 多边形，我使用来自 this topic 的函数。

我的代码如下：

coords<-data.frame(LONG=c(16.9252,16.9363,16.9408,16.8720,16.9167,16.9461,16.9093,16.9457,16.9171,16.8506,16.9471,16.8723,16.9444,16.9212,16.8809,16.9191,16.8968,16.8719,16.9669,16.8845),
LAT=c(52.4064,52.4266,52.3836,52.3959,52.4496,52.3924,52.4012,52.3924,52.3777,52.4368,52.4574,52.3945,52.4572,52.3962,52.3816,52.3809,52.3956,52.3761,52.4236,52.4539))

我的地图在这里：https://docs.google.com/file/d/0B-ZJyVlQBsqlSURiN284dF9YNUk/edit

library(rgdal)
voronoipolygons <- function(x) {
  require(deldir)
  if (.hasSlot(x, 'coords')) {
    crds <- x@coords  
  } else crds <- x
  z <- deldir(crds[,1], crds[,2])
  w <- tile.list(z)
  polys <- vector(mode='list', length=length(w))
  require(sp)
  for (i in seq(along=polys)) {
    pcrds <- cbind(w[[i]]$x, w[[i]]$y)
    pcrds <- rbind(pcrds, pcrds[1,])
    polys[[i]] <- Polygons(list(Polygon(pcrds)), ID=as.character(i))
  }
  SP <- SpatialPolygons(polys)
  voronoi <- SpatialPolygonsDataFrame(SP, data=data.frame(x=crds[,1],
                                                          y=crds[,2], row.names=sapply(slot(SP, 'polygons'), 
                                                                                       function(x) slot(x, 'ID'))))
}

还有我获取 voronoipolygons 的代码：

pzn.coords<-voronoipolygons(coords)
plot(pznall)
plot(pzn.coords,add=T)
points(coords$LONG,coords$LAT)

结果：

我想在我的地图中使用这个 voronoi 多边形作为新的空间多边形。

我将不胜感激！

编辑：

明确地说，我想实现这样的目标（这条线应该由 voronoi 多边形创建）：

Answer 1

稍作修改的函数，采用额外的空间多边形参数并扩展到该框：

voronoipolygons <- function(x,poly) {
  require(deldir)
  if (.hasSlot(x, 'coords')) {
    crds <- x@coords  
  } else crds <- x
  bb = bbox(poly)
  rw = as.numeric(t(bb))
  z <- deldir(crds[,1], crds[,2],rw=rw)
  w <- tile.list(z)
  polys <- vector(mode='list', length=length(w))
  require(sp)
  for (i in seq(along=polys)) {
    pcrds <- cbind(w[[i]]$x, w[[i]]$y)
    pcrds <- rbind(pcrds, pcrds[1,])
    polys[[i]] <- Polygons(list(Polygon(pcrds)), ID=as.character(i))
  }
  SP <- SpatialPolygons(polys)

  voronoi <- SpatialPolygonsDataFrame(SP, data=data.frame(x=crds[,1],
                                                          y=crds[,2], row.names=sapply(slot(SP, 'polygons'), 
                                                                                       function(x) slot(x, 'ID'))))

  return(voronoi)

}

然后做：

pzn.coords<-voronoipolygons(coords,pznall)
library(rgeos)
gg = gIntersection(pznall,pzn.coords,byid=TRUE)
plot(gg)

请注意，gg 是一个 SpatialPolygons 对象，您可能会收到有关 proj4 字符串不匹配的警告。您可能需要将 proj4 字符串分配给其中一个或其他对象。