使用graphviz绘制双向链表

Posted 2023-03-04

【中文标题】使用graphviz绘制双向链表

【英文标题】：Draw doubly linked list using graphviz

【发布时间】：2022-01-23 05:58:36

【问题描述】：

我使用 Graphviz（点）绘制了一个双向链表，如下所示，但节点未对齐。如何对齐节点？

digraph "Doubly Linked List" 
        rankdir=LR;
        node [shape=record];
        e [label="nil" shape=circle];
        a [label=" <ref1> | <data> 1 | <ref2>  "]
        b [label=" <ref1> | <data> 5 | <ref2>  "];
        c [label=" <ref1> | <data> 7 | <ref2>  "];
        d [label="nil" shape=circle];
        e -> a:ref1:c      [arrowhead=dot, arrowtail=vee, dir=both, headclip=false];
        a:ref2:c -> b:data:n [arrowhead=vee, arrowtail=dot, dir=both, tailclip=false];
        b:ref2:c -> c:data:n [arrowhead=vee, arrowtail=dot, dir=both, tailclip=false];
        c:ref2:c -> d      [arrowhead=vee, arrowtail=dot, dir=both, tailclip=false];
        c:ref1:c -> b:data:s [arrowhead=vee, arrowtail=dot, dir=both, tailclip=false];
        b:ref1:c -> a:data:s [arrowhead=vee, arrowtail=dot, dir=both, tailclip=false];

【参考方案1】：

Sroush提供了类似html形状的解决方案，但我找到了一种使用记录节点here的方法，如下：

digraph "Doubly Linked List" 
        rankdir=LR;
        node [shape=record];
        e [label="nil" shape=circle];
        a [label=" <ref1> | <data> 1 | <ref2>  "]
        b [label=" <ref1> | <data> 5 | <ref2>  "];
        c [label=" <ref1> | <data> 7 | <ref2>  "];
        d [label="nil" shape=circle];
        e -> a:ref1:c      [arrowhead=dot, arrowtail=vee, dir=both, headclip=false];
        a:ref2:c -> b:data:n [arrowhead=vee, arrowtail=dot, dir=both, tailclip=false];
        b:ref2:c -> c:data:n [arrowhead=vee, arrowtail=dot, dir=both, tailclip=false];
        c:ref2:c -> d      [arrowhead=vee, arrowtail=dot, dir=both, tailclip=false];
        c:ref1:c -> b:data:s [arrowhead=vee, arrowtail=dot, dir=both, tailclip=false];
        c:ref1:c -> b:data:w[weight = 100, style = invis]; <- add this
        b:ref1:c -> a:data:s [arrowhead=vee, arrowtail=dot, dir=both, tailclip=false];
        b:ref1:c -> a:data:w[weight = 100, style = invis]; <- add this

【参考方案2】：

在高层次上，答案是rank=same ... nodes here ... 但是，记录形状的节点和排名相同的边缘会产生点烧心，或者更准确地说会产生以下错误消息：

Warning: flat edge between adjacent nodes one of which has a record shape - replace records with HTML-like labels
  Edge e -> a
Error: lost e a edge
Error: lost a b edge
Error: lost b a edge
Error: lost b c edge
Error: lost c b edge
Error: lost c d edge

因此，如果我们将节点更改为“类似 html”的形状 (https://graphviz.org/doc/info/shapes.html#href)，您会得到：

digraph "Doubly Linked List" 
        node [shape=plaintext]  // for correct display of table
    rank=same              // all on same rank
        e [label="nil" shape=circle];
        a [label=<<table border="0" cellspacing="0" cellborder="1"><tr>
          <td port="ref1"   fixedsize="true"></td>
      <td port="data"   fixedsize="true">1</td>
      <td port="ref2"   fixedsize="true"></td>
          </tr></table>>]

        b [label=<<table border="0" cellspacing="0" cellborder="1"><tr>
      <td port="ref1"   fixedsize="true"></td>
      <td port="data"   fixedsize="true">5</td>
      <td port="ref2"   fixedsize="true"></td></tr>
          </table>>]

        c [label=<<table border="0" cellspacing="0" cellborder="1"><tr>
      <td port="ref1"   fixedsize="true"></td>
      <td port="data"   fixedsize="true">7</td>
      <td port="ref2"   fixedsize="true"></td>
          </tr></table>>]

        d [label="nil" shape=circle];
    
        e -> a:ref1:c        [arrowhead=dot, arrowtail=vee, dir=both, headclip=false];
        a:ref2:c -> b:data:n [arrowhead=vee, arrowtail=dot, dir=both, tailclip=false];
        b:ref2:c -> c:data:n [arrowhead=vee, arrowtail=dot, dir=both, tailclip=false];
        // added :w to straighten edge
        c:ref2:c -> d:w        [arrowhead=vee, arrowtail=dot, dir=both, tailclip=false];
        c:ref1:c -> b:data:s [arrowhead=vee, arrowtail=dot, dir=both, tailclip=false];
        b:ref1:c -> a:data:s [arrowhead=vee, arrowtail=dot, dir=both, tailclip=false];

（对不起），但它会给你：