r - 如何在 Diagrammer，R 中反转箭头（尾部）？

Question

让我们创建一个非常简单的图表：

niv <- c("A","B","C","D","E")
from <- c("A","A","A","E","B","C","D")
to <-   c("B","C","D","B","C","A","E")
arr <- c(rep("normal",6), "inv")
temp <- data.table(from=factor(from, levels=niv), 
to=factor(to,levels=niv))
nodes <- create_node_df(n=length(niv), label=niv,
width=0.3) 
edges <- create_edge_df(from = temp$from,
to = temp$to, rel = "leading_to", label=temp$from,
arrowhead=arr, penwidth=3, color="blue")   
graph <- create_graph(nodes_df=nodes,edges_df=edges)
render_graph(graph)

该图显示了从一个节点到另一个节点的边。
通常人们用箭头来画那个边缘，但我想用相反的符号画一些，一个尾头。

我发现通过使用参数arrowhead="inv"我可以将箭头改为尾巴。（在我的例子中，从 D 到 E 的边有一条尾巴）。

但是有一个问题，尾巴画错了。我想在边缘的开始处画它（箭头）。

我怎样才能改变它？

有一个参数 rel = "leading_to" 但我无法找到它可以获得的其他值。
还有一个参数“dir”，但我也不知道如何使用它。

谢谢。

一个额外的问题是：如何防止 Diagrammer 在边缘上方写标签？我希望它们不要重叠。

Answer 1

您可以将目录切换为“返回”：

library(DiagrammeR)
library(data.table)
niv <- c("A","B","C","D","E")
from <- c("A","A","A","E","B","C","D")
to <-   c("B","C","D","B","C","A","E")
temp <- data.table(from=factor(from, levels=niv), 
                   to=factor(to,levels=niv))
nodes <- create_node_df(n=length(niv), label=niv,
                        width=0.3) 
edges <- create_edge_df(from = temp$from,
                        to = temp$to, dir = "back", label=temp$from,
                        arrowtail="inv", penwidth=3, color="blue")   
graph <- create_graph(nodes_df=nodes,edges_df=edges)
render_graph(graph)