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R 有向图的方向集_R_Igraph - Fatal编程技术网
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R 有向图的方向集

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R 有向图的方向集,r,igraph,R,Igraph,我有下面的无向图g，它是由河流的形状文件生成的。我想把g转换成一个有向图，其中顶点55是根，所有边的“方向”都指向根顶点（想象一下从网络的所有部分流向根的水流） 无向图示例： library(igraph) g <- structure(list(From = c(48, 37, 39, 32, 38, 36, 49, 46, 31, 26, 33, 35, 18, 23, 45, 41, 42, 47, 52, 51, 50, 54, 16, 14, 8, 10,

我有下面的无向图
g
，它是由河流的形状文件生成的。我想把
g
转换成一个有向图，其中顶点55是根，所有边的“方向”都指向根顶点（想象一下从网络的所有部分流向根的水流）

无向图示例：

library(igraph)

g <- structure(list(From = c(48, 37, 39, 32, 38, 36, 49, 46, 31, 26, 
      33, 35, 18, 23, 45, 41, 42, 47, 52, 51, 50, 54, 16, 14, 8, 10, 
      5, 6, 17, 11, 20, 24, 2, 3, 1, 0, 44, 4, 7, 29, 30, 34, 40, 53, 
      43, 15, 9, 28, 27, 12, 13, 19, 21, 22, 25), To = c(32, 32, 31, 
        31, 33, 33, 45, 45, 23, 23, 26, 26, 16, 16, 35, 35, 41, 41, 50, 
        50, 47, 47, 6, 6, 5, 5, 2, 2, 10, 10, 11, 11, 1, 1, 0, 55, 30, 
        3, 3, 28, 28, 29, 29, 40, 40, 7, 7, 22, 22, 9, 9, 13, 13, 19, 
        19)), class = "data.frame", row.names = c(NA, -55L))

g <- graph.data.frame(g, directed = FALSE) 

l <- igraph::layout_as_tree(g, flip.y = FALSE)
plot(g,
    vertex.size = 10,
    vertex.color = "darkgray",
    layout = l)

库（igraph）

g对于连接顶点a和b的每条边，如果a到55的最短距离小于b到55的最短距离，则b应朝向a。我不熟悉igraph，但我根据这一原理想出了一种方法：


d <- distances(g)[, '55']
dd <- outer(d, d, FUN = '>')

g2 <- get.adjacency(g, sparse = F)
g2 <- g2 * dd
g2 <- igraph::graph.adjacency(g2)

plot(g2,
    vertex.size = 10,
    vertex.color = "darkgray",
    layout = l)



d

d <- distances(g)[, '55']
dd <- outer(d, d, FUN = '>')

g2 <- get.adjacency(g, sparse = F)
g2 <- g2 * dd
g2 <- igraph::graph.adjacency(g2)

plot(g2,
    vertex.size = 10,
    vertex.color = "darkgray",
    layout = l)