R绘图机。如何更改箭头的类型&引用；导致“u”到“u”；

如何更改图表上箭头的类型？ 我想把它们混合在同一张图上

玩具示例：

library(data.table)
niv <- c("A","B","C","D","E","X","Y")
from <- c("A","A","A","A","B","C","D","E", "X", "B")
to <- c("B","C","D","E","X","X","Y","Y","Y", "C")
temp <- data.table(from=factor(from, levels=niv),
to=factor(to,levels=niv), col=c(rep("blue",5), rep("black",5)))

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$from, color=temp$col)   
graph <- create_graph(  nodes_df = nodes, edges_df = edges)
render_graph(graph)

库（data.table）
niv我找到了一种使用参数的方法

arrowhead = myvector

其中我的向量包含元素“无”和/或“正常”。这让我可以压制一些箭。其他有趣的选择是inv或crow。

也许参数rel也有一个选项，但我找不到它