使用 tikz 绘制图表

Question

我正在尝试绘制如下图表：

到目前为止我得到的是：

不知道左上角那个小盒子是从哪里来的......

这是我的代码：

\documentclass[a4paper,10pt]{article}
\usepackage{tikz}
\usetikzlibrary{matrix,shapes,arrows,positioning,chains}

\begin{document}
    \tikzset{
    block/.style={
        rectangle,
        draw,
        text width=10em,
        text centered,
        rounded corners
    },
}

\begin{tikzpicture}
\matrix (m)[matrix of nodes, column  sep=1cm,row  sep=8mm, align=center, nodes={rectangle,draw, anchor=center} ]{
    
    & |[block]| {1}
    &  \\
     & & \\
    |[block]| {1}
    & |[block]| {2}               
    & |[block]| {3}    \\
};
\draw [>=latex,-] (m-1-2) |- (m-3-1);
\end{tikzpicture}

\end{document}

当我尝试从顶部框绘制到中间的矩阵元素时，出现错误消息“没有已知名为 m-2-2 的形状”。

我该怎么办？谢谢

Answer 1

• 您有空行matrix，这是导致图像中出现不想要的正方形的原因（在矩阵中您没有空行）
• 对于所有单元格的命名，您需要nodes in empty cells,向matrix样式选项中
• 在空单元格中没有绘制小方块，你必须将nodes样式更改为coordinate：

\documentclass[a4paper,10pt]{article}
\usepackage{tikz}
\usetikzlibrary{arrows,
                chains, 
                matrix,
                positioning}

\begin{document}
    \tikzset{
    block/.style={
        rectangle,
        draw,
        text width=10em,
        text centered,
        rounded corners
    },
}

    \begin{tikzpicture}
\matrix (m) [matrix of nodes, 
             nodes in empty cells,
             column  sep=1cm,
             row  sep=8mm, 
             align=center, 
             nodes={coordinate}
             ]
{
                & |[block]| {1} &               \\
                &               &               \\
|[block]| {1}   & |[block]| {2} & |[block]| {3} \\
};
\draw       (m-1-2) -- (m-2-2) -| (m-3-1)
                              (m-2-2) -| (m-3-2)
                              (m-2-2) -| (m-3-3);
% or 
%   \draw   (m-1-2) -- (m-3-2)
%           (m-3-1) |- (m-2-2) -| (m-3-3);
    \end{tikzpicture}

\end{document}

（在您的图像中的节点较高，但在 MWE 中您没有定义它们的高度。我遵循您 MWE 中的节点样式定义。）

但是，您的图是树，可以更简单地绘制为树，例如使用森林包：

%\documentclass[a4paper,10pt]{article}
\documentclass[margin=3.141592]{standalone}
\usepackage[edges]{forest}

\begin{document}
    \begin{forest}
    for tree={              
% style of nodes
      draw, semithick, rounded corners,
       text width = 4em, text badly centered,% changed 
   minimum height = 4ex,                     % added
% style of tree 
             edge = {draw=blue},             % changed
           anchor = north,
             grow = south,
    forked edge,            
            s sep =  4mm,   % horizontal ("sibling") distance between nodes
            l sep = 12mm,   % vertical ("level") distance between n odes
         fork sep =  6mm,   % distance from parent to branching point
               }
[1
    [1]
    [2]
    [3]
]
    \end{forest}
\end{document}

绘制了下面的树：

Answer 2

    \documentclass{article}
\usepackage{tikz} 
\usetikzlibrary{arrows.meta, positioning, shapes} 
\begin{document}
\begin{tikzpicture}[
    node distance = 1.5cm and 1cm,
    arr/.style = {draw=blue!50, ultra thick},
    base/.style = {draw, font=\small,
        minimum height=3em, text width=5em, align=center},
    block/.style = {base, fill=#1},
    block/.default = white,
    every edge/.append style = {arr}
    ]
    \node [block] (A) {};
    \node [block, below =of A] (B) {};
    \node [block, right = of B] (C) {};
    \node [block, left = of B] (D) {};
    \coordinate[below=1cm of A] (aux);
    \path[arr] (A) to (B);
    \path[arr](aux) -| (C);
    \path[arr](aux) -| (D);
\end{tikzpicture}
\end{document}