如何用 LaTeX 绘制马尔可夫链路径

Question

我正在尝试在 LateX 中绘制类似的东西（还有更多步骤）：

或者我可以在其他地方创建它并将其作为图形放入 latex 中，但我更喜欢 LaTeX。我认为这TikZ是一种可能性，但我也听说它很难学。

Answer 1

TikZ一开始可能会令人生畏，但值得学习。掌握基础知识后，有更有效的方法来绘制图表，但首先，请专注于几个基本命令：\draw和\node。这应该可以帮助您入门：

\documentclass{article}

\usepackage{tikz}
\usetikzlibrary{shapes} % allows ellipse nodes

\tikzset{ellnode/.style={draw, ellipse, inner sep=.5mm}} % define the style you'll use later

\begin{document}

\begin{tikzpicture}[xscale=1.5] % stretch coordinates in the x-direction. Doesn't affect text.

% draw axis
\draw[thick, ->](-4,0)--(0,0)node[above]{$t$};

% draw tick marks
\draw (-1,.2)--(-1,-.2)node[below]{$-1$};

% draw nodes
\node[ellnode] at (0,1)(n01){$s_3$}; % ellnode is the style you defined earlier
\node[ellnode] at (0,2)(n02){$s_2$}; % n02 is the name of this node for later use
\node[ellnode] at (0,3)(n03){$s_1$};
\node[ellnode] at (-1,1)(n11){$s_3$};
\node[ellnode] at (-1,2)(n12){$s_2$};
\node[ellnode] at (-1,3)(n13){$s_1$};

% draw lines
\draw[->, dashed](n11)--(n03); % draw lines using the node names from above
\draw[->, dashed](n12)--(n03);
\draw[->](n13)--(n02);
\end{tikzpicture}

\end{document}

Answer 2

作为起点。使用循环来定位节点组。节点组的数量由循环的重复次数定义。

\documentclass[border=3.141592]{standalone}
\usepackage{tikz}
\usetikzlibrary{arrows.meta,
                shapes}

\begin{document}
    \begin{tikzpicture}[
            > = Straight Barb,% on grid,
node distance = 7mm and 20mm,
     C/.style = {ellipse, draw, minimum width =1.2em, inner sep=1pt},
every edge/.style = {draw, ->}
                        ]
\foreach \x[count=\i] in {0,-1,-2}
{
\node (n\x1) [C] at (2*\x,0)    {$s_1$};
\node (n\x2) [C,below=of n\x1]  {$s_2$};
\node (n\x3) [C,below=of n\x2]  {$s_3$};
}
\coordinate[below right=7mm and 7mm of n03.south] (R);
\draw[<-, shorten > = -3mm] (R) node[right] {$t$} -- ++ (-8.4,0);
\foreach \x in {0,-1,...,-4}
\draw (R) ++ (2*\x-0.7,1mm) -- ++ (0,-2mm) node[below] {$\x$};
%
\draw   (n-21)   edge[dashed]   (n-12)
        (n-22)   edge           (n-11)
        (n-23)   edge           (n-11)
        (n-11)   edge           (n02)
        (n-12)   edge[dashed]   (n01)
        (n-13)   edge[dashed]   (n01);
    \end{tikzpicture}
\end{document}