如何将一个节点放在链中另一个节点下方

Question

我有以下链：

   \begin{tikzpicture}[start chain=going right,>=latex,node distance=0pt]
     \node[draw,rectangle,on chain,minimum size=1cm] (rr) {$I$};
     \node[draw,rectangle,on chain,draw=white,minimum width=0.8cm]{};
     % the rectangular shape with vertical lines
     \node[rectangle split, rectangle split parts=3,
     draw, rectangle split horizontal,text height=0.5cm,text depth=0.5cm,on chain,inner ysep=0pt] (wa) {};
     \fill[white] ([xshift=-\pgflinewidth,yshift=-\pgflinewidth]wa.north west) 
       rectangle ([xshift=-15pt,yshift=\pgflinewidth]wa.south);
     % the circle
     \node[draw,circle,on chain,minimum size=1cm] (se) {$U_1$};
     \node[draw,diamond,on chain,minimum size=0.2cm,xshift=0.7cm] (see) {};
     { [start branch=numbers going below] } % just a declaration,
     \node[draw,rectangle,on chain,draw=white,minimum width=0.7cm]{};
     % rect2
     \node[rectangle split, rectangle split parts=3,
     draw, rectangle split horizontal,text height=0.5cm,text depth=0.5cm,on chain,inner ysep=0pt] (wa2) {};
     \fill[white] ([xshift=-\pgflinewidth,yshift=-\pgflinewidth]wa2.north west) 
       rectangle ([xshift=-15pt,yshift=\pgflinewidth]wa2.south);
     % the circle 2
     \node[draw,circle,on chain,minimum size=1cm] (se2) {$U_2$};
     % the arrows and labels
     \draw[->] (se.east) -- +(20pt,0) node[midway,above] {$\mu_1$};
     \draw[->] (see.east) -- +(20pt,0) node[midway,above] {$\mu_1$};
     \draw[->] (se2.east) -- +(20pt,0) node[midway,above] {$\mu_2$};
     \draw[<-] (wa.west) -- +(-20pt,0) node[midway,above] {$\lambda$};
   \end{tikzpicture}

如图所示，这是两个队列之间的连接：

但是我想在菱形下方添加另一个带箭头的节点。该怎么做？我搜索了一些解决方案，但它们并不适合我的代码……

Answer 1

首先，你必须加载scopestikz 的库，因此在你的序言中（你应该在上面发布过），你应该添加

\usetikzlibrary{scopes}

然后，按如下方式编辑链的开头：

\begin{tikzpicture}[>=latex,node distance=0pt]
  { [start chain=going right]

最后，将分支放在链的末尾（并相应地编辑标签）：

  % the branch
    {[continue branch=numbers]
      \node[draw,circle,on chain,minimum size=1cm,yshift=-0.7cm] (se3) {$U_3$};
      \draw[->] (see.south) -- +(0,-20pt) node[midway,left] {$\mu_3$};
    }
  } % closing brace from above
\end{tikzpicture}

Answer 2

请注意，如果您愿意，也可以不使用，scopes只需使用第二个链和chainin。但是，出于某种原因，正确定位非常困难。我猜这是因为代码中有很多移位等，但我并不确定。

\documentclass{standalone}
\usepackage{tikz}
\usetikzlibrary{chains,shapes}% both are needed for the original code in the question

\begin{document}

\begin{tikzpicture}[start chain,>=latex,node distance=0pt]
  { [start chain=trunk going right]
     \node[draw,rectangle,on chain,minimum size=1cm] (rr) {$I$};
     \node[draw,rectangle,on chain,draw=white,minimum width=0.8cm]{};
     % the rectangular shape with vertical lines
     \node[rectangle split, rectangle split parts=3,
     draw, rectangle split horizontal,text height=0.5cm,text depth=0.5cm,on chain,inner ysep=0pt] (wa) {};
     \fill[white] ([xshift=-\pgflinewidth,yshift=-\pgflinewidth]wa.north west)
       rectangle ([xshift=-15pt,yshift=\pgflinewidth]wa.south);
     % the circle
     \node[draw,circle,on chain,minimum size=1cm] (se) {$U_1$};
     \node[draw,diamond,on chain,minimum size=0.2cm,xshift=7mm] (see) {};
     \node[draw,rectangle,on chain,draw=white,minimum width=0.7cm]{};
     % rect2
     \node[rectangle split, rectangle split parts=3,
     draw, rectangle split horizontal,text height=0.5cm,text depth=0.5cm,on chain,inner ysep=0pt] (wa2) {};
     \fill[white] ([xshift=-\pgflinewidth,yshift=-\pgflinewidth]wa2.north west)
       rectangle ([xshift=-15pt,yshift=\pgflinewidth]wa2.south);
     % the circle 2
     \node[draw,circle,on chain,minimum size=1cm] (se2) {$U_2$};
  }
  % the branch
  { [start chain=numbers going below]
       \chainin (see);
       \node[draw,diamond,on chain,minimum size=.2cm,yshift=-1cm,xshift=-4.75mm] (branchnode) {};
  }
 % the arrows and labels
 \draw[->] (se.east) -- +(7mm,0) node[midway,above] {$\mu_1$};
 \draw[->] (see.east) -- +(7mm,0) node[midway,above] {$\mu_1$};
 \draw[->] (se2.east) -- +(7mm,0) node[midway,above] {$\mu_2$};
 \draw[<-] (wa.west) -- +(-7mm,0) node[midway,above] {$\lambda$};
 \draw[->] (see.south) -- (branchnode);
\end{tikzpicture}

\end{document}