我想使用tidygraph和ggraph绘制网络图。
我有一个更大的tibble，其中的项目通过from和to连接。一些树是连接的（示例中的a0和b0）。
我想：
1.计算独立树的数量
1.计算平均最大边数=每个独立树的连接数。平均最大边数应该在“下游”计算，即从a0到k2或a4，而不是示例数据中的a0到b0。
示例：

library(tidygraph)
library(igraph)
library(ggraph)
library(tidyverse)

# make edges
edges<- tibble(from = c("a0","a1","a2","a3","b0","b1","c0","c1","a2","k1"),
               to = c("a1","a2","a3","a4","b1","a3","c1","c2","k1","k2"))

# makenodes
nodes  <- unique(c(edges$from,edges$to))
tibble(node=nodes,
       label=nodes) -> nodes

# make correct dataframe                 
routes_igraph <- graph_from_data_frame(d = edges,
                                       vertices = nodes,
                                       directed = TRUE)

routes_tidy <- as_tbl_graph(routes_igraph)

#plot network
ggraph(routes_tidy, layout = "tree") + 
  geom_edge_link() + 
  geom_node_point() + 
  theme_graph() +
  geom_node_text(aes(label = label), repel = TRUE)

创建于2023-04-16带有reprex v2.0.2

期望输出

1.给定edges和nodes的独立树的数量：2
1.每个独立树的平均最大边数：3.5, 2