我想用地理坐标(epsg:27572)对图形的顶点进行空间化,但是当我使用tkplot
函数时tkplot.setcoords()
,坐标是“居中的”,出现一个 0,并且空间化是真实位置的一种镜像对称。一个例子:
library(igraph)
library(tcltk)
relations <- read.table(header=TRUE, check.names= FALSE, textConnection("
A B x y
1 1 2 762920 1872674
2 2 3 778202 1899896
3 3 5 746324 1859111
4 4 5 762920 1872674
5 5 6 762920 1872674
6 6 3 762920 1872674"))
g1 <- graph.data.frame(relations, directed=TRUE)
# fill vertex attributes with coordinates of the table 'relations'
for(i in 1:length(V(g1))){
for(j in 1:nrow(relations)){
if(V(g1)[i]$name==as.character(relations$A[j])){
V(g1)[i]$coordx <- relations$x[j]
V(g1)[i]$coordy <- relations$y[j]
}
}
}
list.vertex.attributes(g1)
# plot the spatialised graph
coords <- cbind(V(g1)$coordx, V(g1)$coordy)
id <- tkplot(g1)
tkplot.setcoords(id, coords)
tkplot.center(id)
tkplot.fit.to.screen(id)
问题是coords
与初始相比已转换:
> tkplot.getcoords(id)
[,1] [,2]
[1,] 762920 27222
[2,] 778202 0
[3,] 746324 40785
[4,] 762920 27222
[5,] 762920 27222
[6,] 762920 27222
tk
显然,坐标的第 2 列已经“居中”为 0。一个节点出现在窗口的右下角。