如何獲得iGraph對象直徑的所有最短路徑？

Question

我想為iGraph對象獲取所有最長的最短路徑。 有這個功能

get.diameter (graph, directed = TRUE, unconnected = TRUE) 

但是它僅返回一條路徑。 因此，如果存在直徑長度最短的路徑，那么它將返回找到的第一個路徑

Answer 1

您可以使用shortest.paths（graph）返回的最短距離矩陣輕松提取哪些節點以什么長度連接。 在R中，您可以這樣使用which()和arr.ind=TRUE ：

longest.shortest.paths <- function(graph){
    # Return edgelist of all node-pairs between which the shortest path
    # in a graph are the longest shortest path observed in that graph.

    # Get all the shortest paths of a graph
    shortest.paths = shortest.paths(graph)

    # Make sure that there are no Inf-values caused by isolates in the graph
    shortest.paths[shortest.paths == Inf] <- 0

    # What nodes in the distance matrix are linked by longest shortest paths?
    el <- which(shortest.paths==max(shortest.paths), arr.ind=TRUE)
    colnames(el) <- c("i","j")
    (el)
}

graph <- erdos.renyi.game(100, 140, "gnm", directed=FALSE)
longest.shortest.paths(graph)