如何将 tikz 节点置于较低级别

Question

使用@Zarko 提供的解决方案马尔可夫链箭头和标签堆叠在一起，我想知道一种方法来插入一个比其他节点处于较低级别的节点，如下图所示：
我已成功创建了带有箭头的 3 个顶部节点。挑战在于创建带有箭头的下部节点。以下是我的 MWE：

\documentclass[border=3.141592]{standalone}

\usepackage{tikz}
\usetikzlibrary{arrows.meta, automata,
    bbox,
    chains, 
    positioning,
    quotes}

\begin{document}

    \begin{tikzpicture}[auto=right, 
        bezier bounding box,
        node distance = 22mm,
        start chain = going right, 
        every edge/.style = {draw, -Stealth, semithick},
        every state/.style = {draw, thick, on chain}
        ]
        \begin{scope}[nodes=state]
            \node (A)   {$1$};
            \node (B)   {$2$};
            \node (C)   {$3$};
            \coordinate (E);
        \end{scope}
        %

        \path[bend left, swap] 
        (A) edge["$.25$"]    (B)
        (B) edge["$.125$"]    (C);

        \path[out=210]
        (B) edge[in=-30, "$.25$"]  (A);

    \end{tikzpicture}

\end{document}

Answer 1

例如，您可以使用below=<distance> of <node>语法将4节点放在下面1并通过以下方式向右移动xshift=

\documentclass[border=3.141592]{standalone}

\usepackage{tikz}
\usetikzlibrary{arrows.meta, automata,
    bbox,
    chains, 
    positioning,
    quotes}

\begin{document}

    \begin{tikzpicture}[auto=right, 
        bezier bounding box,
        node distance = 22mm,
        start chain = going right, 
        every edge/.style = {draw, -Stealth, semithick},
        every state/.style = {draw, thick, on chain}
        ]
        \begin{scope}[nodes=state]
            \node (A)   {$1$};
            \node (B)   {$2$};
            \node (C)   {$3$};
            \node[below=40pt of A, xshift=45pt] (D)   {$4$};
        \end{scope}
        %

        \path[bend left, swap] 
        (A) edge["$.25$"]    (B)
        (B) edge["$.125$"]    (C);
        
        \path 
        (A) edge["$.125$", bend right]      (D)
        (B) edge["$.125$", bend left, swap] (D);

        \path[out=210]
        (B) edge[in=-30, "$.25$"]  (A);

    \end{tikzpicture}

\end{document}