如何在 Graphviz 中用大点装饰边缘？

Question

我想在某些边缘的中心有一个大点（或类似的东西）。以下代码是我能够生成的最好的代码。

digraph BDD {
  ordering = out;
  splines = true;
  edge [arrowhead="none"];
  node [shape = none, label = "SUM"] 0;
  node [shape = circle, label = "x"] 1;
  node [shape = circle, label = "y"] 2;
  node [shape = circle, label = "w"] 3;
  node [shape = none, label = "1"] 4;
  node [shape = circle, label = "z"] 5;
  node [shape = none, label = "1"] 6;
  node [shape = circle, label = "y"] 7;
  node [shape = circle, label = "w"] 8;
  node [shape = none, label = "1"] 9;
  0 -> 1;
  1 -> 2;
  1 -> 7 [arrowhead="dot"]; 
  2 -> 3;
  2 -> 5 [arrowhead="dot"];
  3 -> 4 [arrowhead="dot"]; 
  3 -> 4;
  5 -> 6 [arrowhead="dot"]; 
  5 -> 6;
  7 -> 5;
  7 -> 8;
  8 -> 9;
  8 -> 5;
}

这将产生以下图像，但不太正确，因为点在边缘的末端。

任何人都可以建议我一个解决方案来产生这个：

编辑 1：使用额外的节点作为点会产生不可接受的输出。

digraph BDD {
  ordering = out;
  splines = true;
  edge [arrowhead="none"];
  node [shape = none, label = "SUM"] 0;
  node [shape = circle, label = "x"] 1;
  node [shape = circle, label = "y"] 2;
  node [shape = circle, label = "w"] 3;
  node [shape = none, label = "1"] 4;
  node [shape = circle, label = "z"] 5;
  node [shape = none, label = "1"] 6;
  node [shape = circle, label = "y"] 7;
  node [shape = circle, label = "w"] 8;
  node [shape = none, label = "1"] 9;
  0 -> 1;
  1 -> 2;
  node [shape = point width=0.1] p1p7;
  1 -> p1p7 -> 7; 
  2 -> 3;
  node [shape = point width=0.1] p2p5;
  2 -> p2p5 -> 5;
  node [shape = point width=0.1] p3p4;
  3 -> p3p4 -> 4; 
  3 -> 4;
  node [shape = point width=0.1] p5p6;
  5 -> p5p6 -> 6; 
  5 -> 6;
  7 -> 5;
  7 -> 8;
  8 -> 9;
  8 -> 5;
}

编辑 2：我也可以接受点不完全位于中心的图形。他们只是不能接触节点，也就是说，如果我能 set/make 箭头和节点之间的距离可能就可以了。

Answer 1

你可以创建一个额外的节点（和一个额外的边）来实现它。

digraph {
    node [shape = circle]
    A
    C
    node [shape = point width=0.2]
    B
    edge [arrowhead=none]
    A -> B -> C
}

产生

编辑：

您可以将图表布局到放置所有节点和边的 *.dot 文件中。然后您可以使用您最喜欢的编程语言来读取和修改该文件。还有一些 built-in 脚本语言我还没有尝试过。最后，您使用 nop2 引擎将修改后的 DOT-file 转换为您选择的图像格式。您必须了解如何在贝塞尔样条曲线上放置点。根据文档

splineType
    spline ( ';' spline )*
    where spline    =   (endp)? (startp)? point (triple)+
    and triple  =   point point point
    and endp    =   "e,%f,%f"
    and startp  =   "s,%f,%f"

我们每条边总是有 4+3n (0 <= n) 个点。这些是三次样条的 4 元组，其中一个样条的端点是下一个样条的起点。由于 start-/endpoints 被直接触摸，如果至少有两条样条线（7 点），则它们是放置点的候选对象。一般来说，每个点 [4+3n] 都是候选点。如果我们只有一条样条曲线，这种方法就会失败。我们必须在样条曲线上放置一个点。有效的四元组从 0+3n 开始到 3+3n 结束。

您可以使用任何有效的 x/y 坐标四元组来计算样条曲线上的一个点

x = (x1 + 3*x2 + 3*x3 + x4)/8

这是除法器 2 的简单公式。您可以为 y-coordinate.

做类似的事情

示例：

digraph { rankdir = LR ranksep=1 nodesep=1 pad=0.5
    node [shape = circle]
    edge [arrowhead=none]
    { rank=same
        A -> B
        B -> C
        A -> C
    }
}

给予

digraph {
    graph [bb="0,0,74.575,252",
        nodesep=1,
        pad=0.5,
        rankdir=LR,
        ranksep=1
    ];
    node [label="\N",
        shape=circle
    ];
    edge [arrowhead=none];
    {
        graph [rank=same];
        A        [height=0.5,
            pos="56.575,234",
            width=0.5];
        B        [height=0.5,
            pos="56.575,126",
            width=0.5];
        A -> B       [pos="56.575,215.75 56.575,191.88 56.575,168.01 56.575,144.14"];
        C        [height=0.5,
            pos="56.575,18",
            width=0.5];
        A -> C       [pos="44.02,220.46 24.619,197.84 -9.2417,150.66 2.5745,108 10.795,78.323 31.695,48.606 44.952,31.836"];
        B -> C       [pos="56.575,107.75 56.575,83.878 56.575,60.01 56.575,36.141"];
    }
}

线的边缘

        A -> C       [pos="44.02,220.46 24.619,197.84 -9.2417,150.66 2.5745,108 10.795,78.323 31.695,48.606 44.952,31.836"];

由 2 个样条组成。我们有一个可以直接使用的重叠 start/endpoint

U1 [shape=point width=0.2 color=red pos="2.5745,108"]

从上面的所选边有 2 个有效的 4 元组可供选择，从而在样条曲线上产生 2 个点（对于 divider2）

X1 [shape=point width=0.2 pos="11.59,171.75"]
X2 [shape=point width=0.2 pos="21.87,65.08"]

合并文件

digraph {
    graph [bb="0,0,74.575,252",
        nodesep=1,
        pad=0.5,
        rankdir=LR,
        ranksep=1
    ];
    node [label="\N",
        shape=circle
    ];
    edge [arrowhead=none];
    {
        graph [rank=same];
        A        [height=0.5,
            pos="56.575,234",
            width=0.5];
        B        [height=0.5,
            pos="56.575,126",
            width=0.5];
        A -> B       [pos="56.575,215.75 56.575,191.88 56.575,168.01 56.575,144.14"];
        C        [height=0.5,
            pos="56.575,18",
            width=0.5];
        A -> C       [pos="44.02,220.46 24.619,197.84 -9.2417,150.66 2.5745,108 10.795,78.323 31.695,48.606 44.952,31.836"];
        B -> C       [pos="56.575,107.75 56.575,83.878 56.575,60.01 56.575,36.141"];

        U1 [shape=point width=0.2 color=red pos="2.5745,108"]
        X1 [shape=point width=0.2 pos="11.59,171.75"]
        X2 [shape=point width=0.2 pos="21.87,65.08"]
    }
}

给予

如何在 Graphviz 中用大点装饰边缘？

How to make edges decorated with big dot in Graphviz?

graphviz