How to create a network graph with DiagrammeR? - r

Question

I have a large dataset but let's put a toy example:
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)
But I get this:
Instead of the expected result:
I got that one using first igraph, but I'd like to avoid that step.
UPDATE:
library(data.table)
mydata <- data.table(from=c("John", "John", "Jim"),to=c("John", "Jim", "Jack"), stringsAsFactors = T)
mydata is already using factors. I don't need extra steps converting factors.
I can create the plot with igraph:
library(igraph)
mygraph <- graph_from_data_frame(d=mydata, directed=T)
plot(mygraph)
Or use its object to build a DiagrammeR plot:
V(mygraph)$label = V(mygraph)$name
V(mygraph)$name = factor(V(mygraph)$name, levels=as.character(V(mygraph)$name))
mygraph2 <- from_igraph(mygraph)
render_graph(mygraph2)
But now I try to do it directly from Diagrammer, without igraph:
nodesd = unique(unlist(mydata[,.(from,to)]))
nodes <- create_node_df( n=length(nodesd), label=nodesd)
edges <- create_edge_df(from = mydata$from, to = mydata$to, rel = "leading_to")
graph <- create_graph( nodes_df = nodes, edges_df = edges)
render_graph(graph)
What's the problem?

Answer 1

With your 1st code I got:
> 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)
As #user20650 said, it is an issue with character and factors. So I make a change.
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)
I got the result below.
Result:
I hope it can help.