如何在DiagrammeR中的delete_edge（）之后保留边缘颜色

Question

我通过首先设置基本图，然后添加节点和边，使用DiagrammeR创建了一个图。 我已经在create_graph（）内部的edge_attrs（）中设置了边缘颜色属性。

如果我添加没有颜色属性的新边缘，则它按预期使用了预定义的颜色。 但是，如果我使用delete_edge（）删除边缘之一，则所有边缘的常规边缘属性颜色都会消失。 由于graph $ edges_df不包含任何颜色信息，因此该图默认为黑色。

使用add_node（）时，是否可以将边缘的颜色添加到graph $ edges_df？

我认为可行的唯一方法是添加没有边缘的节点，然后使用add_edge（）分别添加边缘。

这是一个可重现的示例：

library(DiagrammeR)
library(magrittr)

nodes <-
  create_nodes(
    nodes = "a",
    label = "A",
    type = "lower",
    style = "filled",
    shape = "circle",
    color = "orange",
    x = 5,
    y = 4
  )

graph_1 <-
  create_graph(
    nodes_df = nodes,
    graph_attrs = c(
      "layout = neato"
      ),
   edge_attrs = c(
      "relationship = requires",
      "arrowhead = normal",
      "color = 'lightgrey'"
      )
  )

render_graph(graph_1)

graph_1 %>%
  add_node(
    node = "b",
    from = "a",
    label = "B",
    style = "filled",
    shape = "circle",
    color = "orange",
    x = 5,
    y = 3
  ) ->
  graph_2

render_graph(graph_2)

new_edges <- create_edges(
  from = "a",
  to = "a"
)

graph_2 %>%
  add_edges(
    edges_df = new_edges
  ) ->
  graph_3

render_graph(graph_3)

graph_3 %>%
  delete_edge(
    to = "a",
    from = "a"
  ) ->
  graph_4

render_graph(graph_4)

Answer 1

这是我找到的最佳解决方案。 只需忽略常规属性并依靠edges_df。

library(DiagrammeR)
library(magrittr)

nodes <-
  create_nodes(
    nodes = "a",
    label = "A",
    type = "lower",
    style = "filled",
    shape = "circle",
    color = "orange",
    x = 5,
    y = 4
  )

graph_1 <-
  create_graph(
    nodes_df = nodes,
    graph_attrs = c(
      "layout = neato"
    )
  )

render_graph(graph_1)

graph_1 %>%
  add_node(
    node = "b",
    label = "B",
    style = "filled",
    shape = "circle",
    color = "orange",
    x = 5,
    y = 3
  ) %>%
  add_edges(
    edges_df = create_edges(
      from = "a",
      to = "b",
      color = "lightgrey"
    )
  ) ->
  graph_2

render_graph(graph_2)

graph_2 %>%
  add_edges(
    edges_df = create_edges(
      from = "a",
      to = "a",
      color = "lightgrey"
    )
  ) ->
  graph_3

render_graph(graph_3)

graph_3 %>%
  delete_edge(
    to = "b",
    from = "a"
  ) ->
  graph_4

render_graph(graph_4)

编辑：我现在看了来自rich-iannone的delete_edge（）代码。 它基本上基于原始的edge_df，nodes_df，directed和graph_attrs重新构建图形，但不包括node_attrs或edge_attrs，因此它们返回默认值。 一种简单的解决方案是构建一个考虑到这一点的新函数，但我忽略是否与create_graph发生冲突。