如何使用DiagrammeR 创建网络图？

我有一个很大的数据集，但让我们举一个简单的例子：

mydata <- data.table(from=c("John", "John", "Jim"),to=c("John", "Jim", "Jack"))

nodesd=unique(c(mydata$from, mydata$to))
nodes <-   create_node_df(  n=length(nodesd), label=nodesd, type=nodesd)
edges <-   create_edge_df(from = mydata$from, to =  mydata$to,  rel = "leading_to")
graph <-   create_graph(  nodes_df = nodes,     edges_df = edges)
render_graph(graph)

但我明白了：

Instead of the expected result:

我使用第一个 igraph 得到了这个，但我想避免这一步。

UPDATE:

library(data.table)
mydata <- data.table(from=c("John", "John", "Jim"),to=c("John", "Jim", "Jack"), stringsAsFactors = T)

mydata 已经在使用因子。我不需要额外的步骤来转换因子。

我可以用 igraph 创建绘图：

library(igraph)
mygraph <- graph_from_data_frame(d=mydata, directed=T)
plot(mygraph)

或者使用它的对象来构建DiagrammeR图：

V(mygraph)$label = V(mygraph)$name
V(mygraph)$name = factor(V(mygraph)$name, levels=as.character(V(mygraph)$name))
mygraph2 <- from_igraph(mygraph)
render_graph(mygraph2)

但现在我尝试直接从Diagrammer 中执行此操作，而不使用igraph：

nodesd = unique(unlist(mydata[,.(from,to)]))
nodes <-   create_node_df(  n=length(nodesd), label=nodesd)
edges <-   create_edge_df(from = mydata$from, to =  mydata$to,  rel = "leading_to")
graph <-   create_graph(  nodes_df = nodes, edges_df = edges)
render_graph(graph)

有什么问题？

用你的第一个代码我得到：

> mydata <- data.table(from=c("John", "John", "Jim"),to=c("John", "Jim", "Jack"))
> nodesd=unique(c(mydata$from, mydata$to))
> nodes <-   create_node_df(  n=length(nodesd), label=nodesd, type=nodesd)
> edges <-   create_edge_df(from = mydata$from, to =  mydata$to,  rel = "leading_to")
Warning messages:
1: In create_edge_df(from = mydata$from, to = mydata$to, rel = "leading_to") :
  NAs introduced by coercion
2: In create_edge_df(from = mydata$from, to = mydata$to, rel = "leading_to") :
  NAs introduced by coercion
> graph <-   create_graph(  nodes_df = nodes,     edges_df = edges)
> render_graph(graph)

正如@user20650所说，这是性格和因素的问题。所以我做出改变。

mydata <- data.frame(from=c("John", "John", "Jim"),
                     to=c("John", "Jim", "Jack"))
mydata$from <- as.character(mydata$from)
mydata$to <- as.character(mydata$to)
nodesd = unique(c(mydata$from, mydata$to))
nodes <- create_node_df(  n=length(nodesd), label=nodesd, type=nodesd)
edges <- create_edge_df(from = factor(mydata$from, levels = nodesd),
                        to =  factor(mydata$to, levels = nodesd),
                        rel = "leading_to")
graph <- create_graph(nodes_df = nodes, edges_df = edges)
render_graph(graph)

我得到了下面的结果。

Result:

我希望它能有所帮助。