Question

我使用igraph库在R中创建了一个无向的Erdos-Renyi网络。它有100个节点，p = 0.2：

library(igraph)

original <- erdos.renyi.game(100, 0.2, type = c("gnp", "gnm"), directed = FALSE,
    loops = FALSE)

我还创建了两个空网络：

net1 <- graph.empty(100)
net2 <- graph.empty(100)

我根据生成的随机数（0-1之间）从原始网络向net1和net2添加边。如果该随机数在0-0.1之间，则边缘在net1中，如果在0.1-0.9之间，则边缘在net2中，如果在0.9-1之间，则边缘在net1和net2中。

这是我的代码，用于查看原始网络中的所有边缘，并将它们添加到net1，net2或两者中。

i <- 1
while (get.edge(original, E(original)[i])) { #looks through all nodes in original
                                                    #network
    # to generate a random number
    randnum <- runif(1, min=0, max=1)

    #to put the edge in net1, net2 or both
    head <- get.edge(original, E(original)[i])[1]
    tail <- get.edge(original, E(original)[i])[2]
    if (randnum >= 0 && randnum < 0.1) {
        net1 <- add.edges(net1, c(tail, head))  #puts edge in net1
    } else if (randnum >= 0.1 && randnum < 0.9) {
        net2 <- add.edges(net2, c(tail, head))  #puts edge in net2
    } else if (randnum >= 0.9 && randnum <= 1) {
        net1 <- add.edges(net1, c(tail, head))  #puts edge in net1
        net2 <- add.edges(net2, c(tail, head))  #puts edge in net2
    }
    i <- i + 1
}

使用上面的代码，我不断收到此错误消息：

Error in if (id < 1 || id > ec) { : missing value where TRUE/FALSE needed

这条警告信息多次通过'while'循环：

In while (get.edge(original, E(original)[i])) { :
    the condition has length > 1 and only the first element will be used

我不太清楚为什么会收到错误和警告信息，或者如何修复它们。

非常感谢任何帮助。

Answer 1

您可以尝试使用for循环而不是while循环：

for (i in min(E(original)):max(E(original))) { #looks through all the nodes in
                    #the original network from the minimum to the maximum edge
    # to generate a random number
    randnum <- runif(1, min=0, max=1)

    #to put the edge in net1, net2 or both
    head <- get.edge(original, E(original)[i])[1]
    tail <- get.edge(original, E(original)[i])[2]
    if (randnum >= 0 && randnum < 0.1) {
        net1 <- add.edges(net1, c(tail, head))  #puts edge in net1
    } else if (randnum >= 0.1 && randnum < 0.9) {
        net2 <- add.edges(net2, c(tail, head))  #puts edge in net2
    } else if (randnum >= 0.9 && randnum <= 1) {
        net1 <- add.edges(net1, c(tail, head))  #puts edge in net1
        net2 <- add.edges(net2, c(tail, head))  #puts edge in net2
    }
}

使用for循环应该可以摆脱错误和警告消息，而且在这里尝试做的事情也会轻松得多。

在R中的网络中的节点之间创建边

1 个答案: