两个只接触自身的多边形的交点是一条线。使用R中的空间库函数可以轻松计算线长度。
当您从library开始示例时 sp ,您将在该库中找到一个命题。然而,我也给你一个关于新图书馆的建议 sf .

服务提供商

require("rgdal")  
require("rgeos")
library(sp)
library(raster)

download.file("https://www.dropbox.com/s/vbxx9dic34qwz63/Polygons.zip?dl=1", "Polygons.zip")

unzip("Polygons.zip")
Shapefile <- readOGR(".","Polygons")

Touching_List <- gTouches(Shapefile, byid = TRUE, returnDense=FALSE)

# Touching_DF <- setNames(utils::stack(lapply(Touching_List, as.character)), c("TOUCHING", "ORIGIN"))

# ---- Calculate perimeters of all polygons ----
perimeters <- sp::SpatialLinesLengths(as(Shapefile, "SpatialLines"))

# ---- Example with the first object of the list and first neighbor ----
from <- 1
to <- 1
line <- rgeos::gIntersection(Shapefile[from,], Shapefile[Touching_List[[from]][to],])
l_line <- sp::SpatialLinesLengths(line)

plot(Shapefile[c(from, Touching_List[[from]][to]),])
plot(line, add = TRUE, col = "red", lwd = 2)

# ---- Example with the first object of the list and all neighbors ----
from <- 1
lines <- rgeos::gIntersection(Shapefile[from,], Shapefile[Touching_List[[from]],], byid = TRUE)
l_lines <- sp::SpatialLinesLengths(lines)

plot(Shapefile[c(from, Touching_List[[from]]),])
plot(lines, add = TRUE, col = 1 + 1:length(Touching_List[[from]]), lwd = 2)

# ---- All in a lapply loop ----
all.length.list <- lapply(1:length(Touching_List), function(from) {
  lines <- rgeos::gIntersection(Shapefile[from,], Shapefile[Touching_List[[from]],], byid = TRUE)
  l_lines <- sp::SpatialLinesLengths(lines)
  res <- data.frame(origin = from,
                    perimeter = perimeters[from],
                    touching = Touching_List[[from]],
                    t.length = l_lines,
                    t.pc = 100*l_lines/perimeters[from])
  res
})

# ---- Retrieve as a dataframe ----
all.length.df <- do.call("rbind", all.length.list)

t.length 是触摸长度和 t.pc 是相对于原点多边形周长的接触百分比。

编辑:某些共享边界是点(带有 )

如前所述,一些边界可能是唯一的点而不是线。为了解释这种情况,我建议将点的坐标加倍,以创建一条长度为0的线。这需要在出现这种情况时逐个计算与其他多边形的交点。

# Example with the first object of the list and all neighbours
from <- 4
lines <- rgeos::gIntersection(Shapefile[from,], Shapefile[Touching_List[[from]],], byid = TRUE)
# If lines and points, need to do it one by one to find the point
if (class(lines) == "SpatialCollections") {
  list.Lines <- lapply(1:length(Touching_List[[from]]), function(to) {
    line.single <- rgeos::gIntersection(Shapefile[from,], Shapefile[Touching_List[[from]][to],])
    if (class(line.single) == "SpatialPoints") {
      # Double the point to create a line
      L1 <- rbind(line.single@coords, line.single@coords)
      rownames(L1) <- letters[1:2]
      Sl1 <- Line(L1)
      Lines.single <- Lines(list(Sl1), ID = as.character(to))
    } else if (class(line.single) == "SpatialLines") {
      Lines.single <- line.single@lines[[1]]
      Lines.single@ID <- as.character(to)
    }
    Lines.single
  })
  lines <- SpatialLines(list.Lines)
}

l_lines <- sp::SpatialLinesLengths(lines)

plot(Shapefile[c(from, Touching_List[[from]]),])
plot(lines, add = TRUE, col = 1 + 1:length(Touching_List[[from]]), lwd = 2)

# Corrected for point outputs: All in a lapply loop
all.length.list <- lapply(1:length(Touching_List), function(from) {
  lines <- rgeos::gIntersection(Shapefile[from,], Shapefile[Touching_List[[from]],], byid = TRUE)
  if (class(lines) == "SpatialCollections") {
    list.Lines <- lapply(1:length(Touching_List[[from]]), function(to) {
      line.single <- rgeos::gIntersection(Shapefile[from,], Shapefile[Touching_List[[from]][to],])
      if (class(line.single) == "SpatialPoints") {
        # Double the point to create a line
        L1 <- rbind(line.single@coords, line.single@coords)
        rownames(L1) <- letters[1:2]
        Sl1 <- Line(L1)
        Lines.single <- Lines(list(Sl1), ID = as.character(to))
      } else if (class(line.single) == "SpatialLines") {
        Lines.single <- line.single@lines[[1]]
        Lines.single@ID <- as.character(to)
      }
      Lines.single
    })
    lines <- SpatialLines(list.Lines)
  }
  l_lines <- sp::SpatialLinesLengths(lines)
  res <- data.frame(origin = from,
                    perimeter = perimeters[from],
                    touching = Touching_List[[from]],
                    t.length = l_lines,
                    t.pc = 100*l_lines/perimeters[from])
  res
})

all.length.df <- do.call("rbind", all.length.list)

这也适用于库 ,但你显然选择了 服务提供商 ,我不会更新此部分的代码。也许以后。。。

使用库计算多边形共享边界长度 旧金山

library(sf)
Shapefile.sf <- st_read(".","Polygons")

# ---- Touching list ----
Touching_List <- st_touches(Shapefile.sf)
# ---- Polygons perimeters ----
perimeters <- st_length(Shapefile.sf)

# ---- Example with the first object of the list and first neighbour ----
from <- 1
to <- 1
line <- st_intersection(Shapefile.sf[from,], Shapefile.sf[Touching_List[[from]][to],])
l_line <- st_length(line)

plot(Shapefile.sf[c(from, Touching_List[[from]][to]),])
plot(line, add = TRUE, col = "red", lwd = 2)

# ---- Example with the first object of the list and all neighbours ----
from <- 1
lines <- st_intersection(Shapefile.sf[from,], Shapefile.sf[Touching_List[[from]],])
lines <- st_cast(lines) # In case of multiple geometries (ex. from=71)
l_lines <- st_length(lines)

plot(Shapefile.sf[c(from, Touching_List[[from]]),])
plot(lines, add = TRUE, col = 1:length(Touching_List[[from]]), lwd = 2)

# ---- All in a lapply loop ----
all.length.list <- lapply(1:length(Touching_List), function(from) {
  lines <- st_intersection(Shapefile.sf[from,], Shapefile.sf[Touching_List[[from]],])
  lines <- st_cast(lines) # In case of multiple geometries
  l_lines <- st_length(lines)
  res <- data.frame(origin = from,
                    perimeter = as.vector(perimeters[from]),
                    touching = Touching_List[[from]],
                    t.length = as.vector(l_lines),
                    t.pc = as.vector(100*l_lines/perimeters[from]))
  res
})

# ---- Retrieve as dataframe ----
all.length.df <- do.call("rbind", all.length.list)

只是为了补充斯巴斯蒂安·罗切特的回答,我认为功能 st_length sf 包不适用于多边形(请参见此 post ). 相反,我建议使用函数 st_perimeter 在里面 lwgeom

(我想对答案发表评论,但我没有足够的声誉)