R 图解程序流程图：对齐垂直节点

我正在使用

DiagrammeR

R包绘制流程图，下面是用于生成模拟示例的代码：

library(DiagrammeR)
grViz("digraph flowchart {

  # node type 1: starting and ending node
  node [fontname = Helvetica, shape = oval]
  start [label = '@@1']
  node [fontname = Helvetica, shape = oval]
  pro2 [label = '@@6']

  # node type 2: decision
  node [fontname = Helvetica, shape = diamond]
  dec1 [label = '@@2']
  dec2 [label = '@@3']
  node [fontname = Helvetica, shape = diamond]
  dec3 [label = '@@4']

  # node type 3: process 
  node [fontname = Helvetica, shape = rectangle]
  pro1 [label = '@@5']
  node [fontname = Helvetica, shape = rectangle]        
  pro3 [label = '@@7']
  
  # specify which nodes are of the same 'rank' so that they'll be drawn at the same level
  {rank = same; dec2 pro3}
  {rank = same; pro1 dec3}
  
  # edge definitions with the node IDs
  edge[tailclip = true, headclip = true];
  start -> dec1
  dec1 -> dec2 [fontname = Helvetica, label = '', headport = 'n', tailport = 's']
  dec1 -> pro3 [fontname = Helvetica, label = '', headport = 'n', tailport = 'e']
  dec2 -> pro1 [fontname = Helvetica, label = '', tailport = 's']
  dec2 -> pro3 [fontname = Helvetica, label = '']
  pro3 -> dec3 [fontname = Helvetica, label = '', headport = 'n']
  dec3 -> pro2 [fontname = Helvetica, label = '', headport = 'n', tailport = 's']
  dec3 -> pro3 [fontname = Helvetica, label = '', headport = 'e', tailport = 'e']
  pro1 -> dec1 [fontname = Helvetica, label = '', headport = 'w']
  }

  [1]: 'START'
  [2]: 'decision 1'
  [3]: 'decision 2'
  [4]: 'decision 3'
  [5]: 'process 1'
  [6]: 'END'
  [7]: 'process 3'
  ")

创建的流程图如下所示：我希望

• 过程1可以垂直对齐，如上面的“开始”、“决定1”和“决定2”（目前它位于左侧，看起来很尴尬；从决定2到过程1的箭头应该是直的，而不是弯曲的
• 决策3和END可以与上面的“流程3”垂直对齐；流程3到决策3的箭头应该是直的，而不是弯曲的
• “很好”，但不是必需的：有没有办法将“弯曲”箭头改为直箭头？例如，我希望让箭头的尾部从流程1的西侧开始，水平地直一点，然后垂直地直到与决策1相同的高度，最后水平地直到决策1的西侧

谢谢你的帮助

---

对于1和2，添加

{rankdir='TB'；start->dec1->dec2->pro1}；{rankdir='TB'；pro3->dec3->pro2}；

做你想做的事（你需要删除其他边）。Re 3你可能需要添加一个虚拟/不可见的节点（这些是搜索词）Re 3；给出了一个例子。