Graphviz:如何在 HTML 表格单元格之间创建边？

Question

请考虑以下代码:

digraph G {
    node [shape=plaintext]

    a [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
                           <TR><TD ID="first" BGCOLOR="gray">first</TD></TR>
                           <TR><TD ID="second" PORT="f1">second</TD></TR>
                           <TR><TD ID="third" PORT="f2">third</TD></TR>
              </TABLE>>];

    b [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
                           <TR><TD ID="first" BGCOLOR="gray">first</TD></TR>
                           <TR><TD ID="second" PORT="f1">second</TD></TR>
                           <TR><TD ID="third" PORT="f2">third</TD></TR>
              </TABLE>>];

    a:first -> b:first;
}

我收到了相当多的警告:

laci@nitehawk ~ $ dot records.gv -T pdf > records.pdf
Warning: Illegal attribute ID in <TD> - ignored
Warning: Illegal attribute ID in <TD> - ignored
Warning: Illegal attribute ID in <TD> - ignored
in label of node a
Warning: Illegal attribute ID in <TD> - ignored
Warning: Illegal attribute ID in <TD> - ignored
Warning: Illegal attribute ID in <TD> - ignored
in label of node b
Warning: node a, port first unrecognized
Warning: node b, port first unrecognized

根据documentation TD的ID属性应该是合法的。我错过了什么？

如何引用单个单元格并在它们之间创建边缘？

Answer 1

为了完整起见，这里是实际工作的完整源代码:

digraph G {
    node [shape=plaintext]

    a [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
                           <TR><TD PORT="c" BGCOLOR="gray">first</TD></TR>
                           <TR><TD PORT="d">second</TD></TR>
                           <TR><TD PORT="e">third</TD></TR>
              </TABLE>>];

    b [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
                           <TR><TD PORT="c" BGCOLOR="gray">first</TD></TR>
                           <TR><TD PORT="d">second</TD></TR>
                           <TR><TD PORT="e">third</TD></TR>
              </TABLE>>];

    a:c -> b:c;
}