无法使 igraph edgelist 工作，矩阵的 ncol returns NULL

Question

我对单行矩阵有问题，我无法将它加载到有向图

> network_matrix
     login      mentions weight
[1,] "rtomayko" "author" "1"   
> str(network_matrix)
 chr [1, 1:3] "rtomayko" "author" "1"
 - attr(*, "dimnames")=List of 2
  ..$ : NULL
  ..$ : chr [1:3] "login" "mentions" "weight"
> typeof(network_matrix)
[1] "character"
> g = graph.edgelist(network_matrix[,1:2], directed = TRUE)
Error in graph.edgelist(network_matrix[, 1:2], directed = TRUE) : 
  graph_from_edgelist expects a matrix with two columns
>

第 3 列是体重，我想跳过它

> is.matrix(network_matrix)
[1] TRUE
> ncol(network_matrix)
[1] 3

很好，但是：

> ncol(network_matrix[,1:2])
NULL

我不明白为什么它是 NULL 并阻止来自运行ning 的 igraph structure.generators.R 代码，因为 ncol(el) != 2检查。

这是我的代码，它处理以前的数据，我现在想运行:

g = graph.edgelist(network_matrix[,1:2], directed = TRUE)
E(g)$weight=as.numeric(network_matrix[,3])

谢谢！

Answer 1

需要设置drop=F

g = graph.edgelist(network_matrix[,1:2, drop=F], directed = TRUE)

感谢@user20650

结案

无法使 igraph edgelist 工作，矩阵的 ncol returns NULL

Cannot get igraph edgelist working, ncol for matrix returns NULL

r

igraph