具有单向和双向边缘的网络

Question

我有由互动对组成的数据，我想将其表示为网络。虽然大多数交互是单向的，但有些是双向的，我希望能够代表这一点。

我可以按颜色执行此操作，但是对于单向交互而言，方向很重要，因此我认为我可以使用箭头，但是我不知道如何从双向边缘移除箭头（或在另一端添加箭头）。我正在使用tidygraph和ggraph软件包，由于我不知道该如何传递给geom_edge_link中的美学调用，因此正在努力实现它。我还尝试了对tbl_graph对象进行子设置，并将其作为数据来分隔geom_edge_link层，但这没有用。

这是我到目前为止的MWE：

nodes <- structure(list(node = structure(c(1L, 2L, 5L, 6L, 8L, 7L, 4L, 
3L), .Label = c("A", "B", "D", "E", "F", "Q", "S", "T"), class = "factor")), .Names = "node", row.names = c(NA, 
-8L), class = "data.frame")

df <- structure(list(from = c("A", "B", "F", "Q", "T", "S", "A", "T", 
"F"), to = c("E", "D", "Q", "S", "F", "T", "D", "A", "E"), status = c("Bi", 
"Bi", "Uni", "Uni", "Uni", "Uni", "Uni", "Uni", "Uni"), weight = c(2, 
2, 1, 1, 1, 1, 1, 1, 1)), .Names = c("from", "to", "status", 
"weight"), row.names = c(NA, -9L), class = c("tbl_df", "tbl", 
"data.frame"))

library(tidygraph)
library(ggraph)

tbl_graph(nodes = nodes, edges = df, directed = T) %>% 
  ggraph(layout = 'linear', circular = TRUE) + 
  geom_edge_link(aes(colour = status),
                 arrow = arrow(length = unit(4, 'mm')),
                 start_cap = circle(3, 'mm'),
                 end_cap = circle(3, 'mm')) + 
  geom_node_point(size = 5) + 
  coord_fixed() +
  geom_node_text(aes(label = node), repel = T) +
  scale_edge_width(range = c(0.5, 1)) + 
  theme_graph()