Graphviz---随机节点顺序和经过标签的边

Question

我有以下点文件:

digraph finite_state_machine {
    {
        rank=same;
        node [shape = doublecircle]; q_5;
        node [shape = circle];
        q_1 -> q_2 [ label = "." ];
        q_1 -> q_2 [ label = "\epsilon" ];
        q_2 -> q_1 [ label = "\epsilon" ];
        q_2 -> q_3 [ label = "a" ];
        q_3 -> q_4 [ label = "^\wedge a" ];
        q_3 -> q_4 [ label = "\epsilon" ];
        q_4 -> q_3 [ label = "\epsilon" ];
        q_4 -> q_5 [ label = "b" ];
    }
}

我的印象是节点会按照它们被提及的顺序出现。但顺序对我来说似乎是随机的。我希望顺序是从左到右，按照下标的顺序。另外，边缘穿过标签，我怎样才能避免这种情况？

这是当前图像:

Answer 1

Graphviz 确实根据彼此之间的边来布局节点，而不是按照出现的顺序。如果您希望边不影响任何节点的位置，可以通过添加 constraint=false 来实现。

因此，该图:

digraph finite_state_machine {
  pad=0.2;
    {
        rank=same;
        node [shape = doublecircle]; q_5;
        node [shape = circle];
        q_1 -> q_2 [ label = "." ];
        q_1 -> q_2 [ label = "\epsilon", constraint=false ];
        q_2 -> q_1 [ label = "\epsilon", constraint=false ];
        q_2 -> q_3 [ label = "a" ];
        q_3 -> q_4 [ label = "^\wedge a" ];
        q_3 -> q_4 [ label = "\epsilon", constraint=false ];
        q_4 -> q_3 [ label = "\epsilon", constraint=false ];
        q_4 -> q_5 [ label = "b" ];
    }
}

会给你带来:

我必须添加 pad 以免某些标签被切断。