tikz 图表中消失的箭头

Question

我正在 tikz 中绘制有向无环图。它们看起来很棒，但是当我尝试指定箭头输入坐标时，箭头有时会消失，我想知道为什么。

我的序言是：

\documentclass{article}
\usepackage{graphicx}
\usepackage{tikz}
\usepackage[landscape]{geometry}
\usepackage{float}
\usepackage{listings}
%load options
\usetikzlibrary{positioning, calc, shapes.geometric, shapes.multipart,
        shapes, arrows.meta, arrows, decorations.markings, external, trees}

%Create custom arrow style:
\tikzstyle{Arrow} = [
thick,
decoration={
markings,
mark=at position 1 with {
\arrow[thick]{latex}
}
},
shorten >= 3pt, preaction = {decorate}
]

当我使用以下代码时，c-->Y 边缘上的所有箭头都会显示出来：

\begin{figure}[H]
\begin{tikzpicture}
    \node (1) {};
    \node [right =of 1] (2)  {E};
    \node [right =of 2] (3) {};
    \node [right =of 3] (4) {Y};
    \node [left =of 1] (5) {C};
    \node [above =of 3] (6) {M};

    \draw[Arrow] (2.east)--(4.west);
    \draw[Arrow] (2) to (6);
    \draw[Arrow] (6) to (4);
    \draw[Arrow] (5) to [out=-25, in=-160] (4);
    \draw[Arrow] (5) to (6);
    \draw[Arrow] (5.east)--(2.west);
\end{tikzpicture}
\caption{}
\end{figure}

然而，当我改变时\draw[Arrow] (5) to [out=-25, in=-160]箭头\draw[Arrow] (5) to [out=-25, in=-122]消失了：

\begin{figure}[H]
\begin{tikzpicture}
    \node (1) {};
    \node [right =of 1] (2)  {E};
    \node [right =of 2] (3) {};
    \node [right =of 3] (4) {Y};
    \node [left =of 1] (5) {C};
    \node [above =of 3] (6) {M};

    \draw[Arrow] (2.east)--(4.west);
    \draw[Arrow] (2) to (6);
    \draw[Arrow] (6) to (4);
    \draw[Arrow] (5) to [out=-25, in=-122] (4);
    \draw[Arrow] (5) to (6);
    \draw[Arrow] (5.east)--(2.west);
\end{tikzpicture}
\caption{}
\end{figure}

这只是我经常遇到的一个问题的简单示例，它让我无法精确控制更复杂的图表。有人能解释一下为什么会发生这种情况以及可能的解决方法吗？

Answer 1

我不会使用该markings库，尤其是对于路径尖端的箭头。该库已内置于 PGF/TikZ 中，使用当前版本时有很多自定义选项arrows.meta图书馆（与弃用的选项相比，它使用大写的箭头提示名称）。

只需简单操作，-Latex[scale=.8]您就可以调整大小，使其看起来像您的输出，但实际上在末尾放置一个箭头，而无需猜测任何值。

---

tikzcd我添加了由库提供的环境生成的相同图表cd。它使用不同的节点间距离，但可以使用column sep/row sep和不同的s 进行调整。（不过，示例中没有inner sep空节点1和。）3tikzcd

第一个图表还具有库提供的可选设置，cd这对于具有不同高度和深度的更多不同内容的节点可能很有用。

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对于弯曲路径，加载bending库（已设置arrows=[flex]）但arrows=[bend]在这些路径上应用漂亮的箭头提示可能是一个好主意。

代码

\documentclass[tikz]{standalone}
\usetikzlibrary{arrows.meta, cd, decorations.markings, positioning}
\begin{document}
\begin{tikzpicture}[
  % this might be useful for more varied content:
%  nodes=asymmetrical rectangle, commutative diagrams/center yshift=.75ex,
  Arrow/.style={thick, -{Latex[scale=.8]}},
]
\node (1) {};
\node [right=of 1] (2) {E};
\node [right=of 2] (3) {};
\node [right=of 3] (4) {Y};
\node [left =of 1] (5) {C};
\node [above=of 3] (6) {M};

\path[Arrow] (2) edge (4) edge (6)
             (6) edge (4)
             (5) edge[out=-25, in=-122] (4)
                 edge (6) edge (2);
\end{tikzpicture}
\begin{tikzpicture}[Arrow/.style={
  thick, shorten >= 3pt, preaction = decorate,
  decoration={name=markings, mark=at position 1 with {\arrow[thick]{latex}}}}]
\node              (1) {};
\node [right=of 1] (2) {E};
\node [right=of 2] (3) {};
\node [right=of 3] (4) {Y};
\node [left =of 1] (5) {C};
\node [above=of 3] (6) {M};

\draw[Arrow] (2.east)--(4.west);
\draw[Arrow] (2) to (6);
\draw[Arrow] (6) to (4);
\draw[Arrow] (5) to [out=-25, in=-122] (4);
\draw[Arrow] (5) to (6);
\draw[Arrow] (5.east)--(2.west);
\end{tikzpicture}
\begin{tikzcd}[
  arrow style=tikz, >={Latex[scale=.8]},
  arrows=thick, math mode=false, center yshift=+.75ex]
 & & & M \ar[dr] \\
C \ar[rr] \ar[rrru] \ar[rrrr, out=-25, in=-122] 
 & & E \ar[ru] \ar[rr]
     & & Y
\end{tikzcd}
\end{document}

输出

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