在 R 中如何从 igraph 中删除小社区

Question

在 R 网络图中如何删除两个小社区（两个节点与一条边相连，与其他节点没有连接，如本例中的 jane 和 ike：

library(igraph)
g <- graph_from_literal(Andre----Beverly:Diane:Fernando
                    Beverly--Garth:Ed,
                    Carol----Andre:Diane:Fernando,
                    Diane----Andre:Carol:Fernando:Beverly,
                    Fernando-Carol:Andre:Diane:Heather,
                    Jane-----Ike )
plot(g, vertex.label.color="blue", vertex.label.cex=1.5,
 vertex.label.font=2, vertex.size=25, vertex.color="white",
 vertex.frame.color="white", edge.color="black")

Answer 1

这是一个可能的解决方案，components用于查找子图然后进行一些计数。您还可以查看igraph诸如groups和sizes执行这些获取子图顶点计数和顶点名称的操作的函数。

library(igraph)
g <- graph_from_literal(Andre----Beverly:Diane:Fernando,
                        Beverly--Garth:Ed,
                        Carol----Andre:Diane:Fernando,
                        Diane----Andre:Carol:Fernando:Beverly,
                        Fernando-Carol:Andre:Diane:Heather,
                        Jane-----Ike )

#get all subgraphs
sub_gs <- components(g)$membership

#find which subgraphs have 2 nodes
small_sub <- names(which(table(sub_gs) == 2))

#get names of nodes to rm
(rm_nodes <- names(which(sub_gs == small_sub)))
# [1] "Jane" "Ike" 

#remove nodes by name
g2 <- delete_vertices(g, rm_nodes)