[英]Output shapefile for the igraph network in R
Hello I have a network in R using the igraph library 你好我在R中使用igraph库有一个网络
Vertices: 616
Edges: 6270
Directed: TRUE
No graph attributes.
Vertex attributes: name, Lat, Lon.
Edge attributes: V3.
How can I generate two shapefiles for the Vertices and the Edges using the Lat, Lon info in the vertex? 如何使用顶点中的Lat,Lon信息为顶点和边创建两个shapefile?
You can do this using the sp
and maptools
packages. 您可以使用sp
和maptools
包执行此操作。 There are handy functions writePointsShape()
and writeLinesShape()
in maptools
that will write to the ESRI shapefile format. 有方便的功能writePointsShape()
和writeLinesShape()
在maptools
将写入ESRI shape文件格式。
Before doing this, it is necessary to extract the lat/lon information from the graph vertices and put it into a SpatialPoints
object for the vertices, and a SpatialLinesDataFrame
object for the edges. 在此之前,有必要提取从图形顶点经/纬度信息,并把它变成一个SpatialPoints
对象的顶点和SpatialLinesDataFrame
的边缘对象。
This code produces a very simple igraph
object for the following example: 此代码为以下示例生成一个非常简单的igraph
对象:
library(igraph)
## Produce a ring graph with 4 vertices
x <- graph.ring(4)
## Add lat/lon information to vertices
V(x)$lat <- c(50, 50, 51, 51)
V(x)$lon <- c(40, 41, 41, 40)
Now, create the SpatialPoints
object for the vertices 现在,为顶点创建SpatialPoints
对象
library(sp)
library(maptools)
## Create SpatialPoints object containing coordinates
xV <- SpatialPoints(cbind(V(x)$lon, V(x)$lat))
## Write vertices to a shapefile
writePointsShape(xV, fn="vertices")
Finally, create the SpatialLinesDataFrame
object for the edges. 最后,为边创建SpatialLinesDataFrame
对象。 This is a little messy, but I am yet to find a quick way to produce a SpatialLines object given coordinates. 这有点乱,但我还没有找到一种快速的方法来生成给定坐标的SpatialLines对象。
## Create SpatialLinesDataFrame object describing edges
edges <- get.edgelist(x)+1
edges <- cbind(edgeNum=1:nrow(edges), v1=edges[,1], v2=edges[,2])
xE <- apply(edges, 1, function(i) Lines(Line(cbind(c(V(x)$lon[i["v1"]], V(x)$lon[i["v2"]]), c(V(x)$lat[i["v1"]], V(x)$lat[i["v2"]]))), ID=as.character(i["edgeNum"])))
xE <- SpatialLinesDataFrame(SpatialLines(xE), data=data.frame(edgeNum=1:nrow(edges)))
## Write edges to a shapefile
writeLinesShape(xE, fn="edges")
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