网络流图中的标记弧

Question

我使用下面的 Latex 代码制作了下图。有人能解释一下如何使节点和文本变大并标记弧吗，例如将标签 3 添加到连接 n1 和 n2 的弧上吗？

\documentclass[]{article}
\usepackage{tikz}
\usetikzlibrary{calc}
\begin{document}
\begin{tikzpicture}[font=\sf]
\node[draw,circle,label=below:$n_1$] (n1) at (0,0){};
\node[draw,circle,label=above:$n_2$] (n2) at (2,2){}; 
\node[draw,circle,label=above:$n_3$] (n3) at (2,1){}; 
 \draw[thick,-latex] (n1) -- (n2);

 
\end{tikzpicture}
\end{document}

我的目标是制作一幅像这样的图像。

Answer 1

编辑：在第一个版本的机器人示例中，我忘记了边缘标签。现在已添加。

像这样？

\documentclass[margin=3mm]{standalone}
\usepackage{tikz}
\usetikzlibrary{arrows.meta,
                positioning,
                quotes}


\begin{document}
    \begin{tikzpicture}[
node distance = 8mm and 12mm,
V/.style = {circle, draw, font=\sffamily, minimum size=2em, inner sep =2pt},
every edge/.style = {draw, -{Straight Barb[scale=0.8]}, shorten > = 1mm},
every edge quotes/.style = {auto, font=\small\sffamily, sloped}
                        ]
\node[V] (n1) {n1};
\node[V, above right=of n1] (n2)    {n2};
\node[V, at={(n1 -| n2)}]   (n3)    {n3};
\node[V, below right=of n1] (n4)    {n4};
\node[V, right=of n2]       (n5)    {t};
%
\path   (n1) edge ["3"] (n2)
        (n1) edge (n3)
        (n1) edge (n4)
        (n3) edge[red, "5"]      (n5);
\end{tikzpicture}
\end{document}

附录： 对于定位，您可以使用选项on grid。在这种情况下，节点之间的距离是通过它们的中心来测量的，即它们在网格上的距离​​由以下公式指定node distance：

\documentclass[margin=3mm]{standalone}
\usepackage{tikz}
\usetikzlibrary{arrows.meta,
                positioning,
                quotes}


\begin{document}
    \begin{tikzpicture}[
node distance = 11mm and 22mm, on grid,
V/.style = {circle, draw, font=\sffamily, minimum size=2em, inner sep =2pt},
every edge/.style = {draw, -{Straight Barb[scale=0.8]}, shorten > = 1mm},
every edge quotes/.style = {auto, font=\small\sffamily, sloped}
                        ]
\node[V] (n1) {n1};
\node[V, above right=of n1] (n2)    {n2};
\node[V, right=of n1]       (n3)    {n3};
\node[V, below right=of n1] (n4)    {n4};
\node[V, right=of n2]       (n5)    {t};
%
\path   (n1) edge ["3"]  (n2)
        (n1) edge        (n3)
        (n1) edge        (n4)
        (n3) edge[red, "5"]     (n5);
\end{tikzpicture}
\end{document}

结果与以前类似：