R：如何从根节点遍历到iGraph数据对象中的每个叶节点并获取路径？

Question

我是R的新手，我有一个图形对象，我是从数据框对象＆＃34; allTog＆＃34;如下图所示：

library(igraph)
df.g <- graph.data.frame(d = allTog, directed = TRUE)
plot(df.g, vertex.label = V(df.g)$name)

allTog数据框由

给出

allTog <- data.frame(
    source = c("chamber", "chamber", "chamber", "chamber", "chamber", 
    "check", "check", "issue", "issue", "issue"), 
    target = c("check", "issue", "leak", "process", "found", "power", 
    "customer", "customer", "wafer", "replaced") 
    )

列＆＃34; row.names＆＃34;和＆＃34;价值观＆＃34;在这里没有兴趣。

如何遍历每个根节点（在本例中为＃34; chamber＆＃34;）到每个叶节点并获取路径，即所有节点（顶点）名称？我正在寻找通用解决方案，因为我的根节点可以随着每次运行代码而改变。例如，在下一次运行中，根节点可以是＆＃34; issue＆＃34;。

我想要的输出是：

chamber->check->power
chamber->issue->replaced
chamber->process
chamber->issue->customer

等等......

Answer 1

怎么样

root <- "chamber"
leafnodes <- sapply(V(df.g), function(x) length(neighbors(df.g,x))==0 )
paths <- get.all.shortest.paths(df.g, V(df.g)[root], leafnodes)$res
sapply(paths, function(vs) paste(V(df.g)[vs]$name, collapse="->"))

列出了您可以访问的所有叶节点

# [1] "chamber->leak"            "chamber->process"         "chamber->found"          
# [4] "chamber->check->power"    "chamber->issue->customer" "chamber->check->customer"
# [7] "chamber->issue->wafer"    "chamber->issue->replaced"