如何在 pgfplots 中绘制穿过组图的线？

Question

这个问题让我在过去 10-20 小时里抓狂不已。我有一个组图 (pgfplots)，其中有两个图一个在另一个之下。我想画一条垂直线（例如 x=150e-6 处的帮助线），穿过所有图。

axis在环境内绘图时，nextgroupplot我可以使用类似这样的方法：\draw[thin] (axis cs:150e-6,\pgfkeysvalueof{/pgfplots/ymin}) -- (axis cs:150e-6,\pgfkeysvalueof{/pgfplots/ymax});但这只允许我在其中一个子图上绘图。如果我超出轴环境，我可以在整个上绘图{tikzpicture}，但我不能使用轴参考。

\begin{figure*}[h]
\centering
\begin{tikzpicture}

\begin{groupplot}[
      group style = {group size=1 by 2, x descriptions at=edge bottom, vertical sep=0.2cm},
      ytick={0, 1.8},
      ymin=0,
      ymax=3,
      xmin=0,
      xmax=550e-6,
      change x base=true,
      x SI prefix=micro]

\nextgroupplot
\addplot table [x index = {0}, y index = {1}, col sep=comma] {plots/plot1reduced.csv};

\nextgroupplot[x unit=s]
\addplot table [x index = {0}, y index = {3}, col sep=comma] {plots/plot1reduced.csv};

\draw[thin] (axis cs:150e-6,\pgfkeysvalueof{/pgfplots/ymin}) -- (axis cs:150e-6,\pgfkeysvalueof{/pgfplots/ymax});

\end{groupplot}
\end{tikzpicture}
\caption{Case 1}
\label{fig:case1plot}
\end{figure*}

Answer 1

\coordinate您可以在顶部和底部添加groupplot，然后使用它们作为参考绘制线条。

\documentclass{standalone}

\usepackage{pgfplots}
\usepgfplotslibrary{groupplots,units}
\begin{document}
\begin{tikzpicture}

\begin{groupplot}[
      group style = {group size=1 by 2, x descriptions at=edge bottom, vertical sep=0.2cm},
      ytick={0, 1.8},
      ymin=-3,
      ymax=3,
      xmin=0,
      xmax=3]

\nextgroupplot
\addplot {x};
\coordinate (top) at (axis cs:1,\pgfkeysvalueof{/pgfplots/ymax});

\nextgroupplot[x unit=s]
\addplot {-x};

\coordinate (bot) at (axis cs:1,\pgfkeysvalueof{/pgfplots/ymin});

\end{groupplot}
\draw [thin] (top) -- (bot);
\end{tikzpicture}
\end{document}

Answer 2

你可以这样做

\draw[thick,red] (group c1r1.north) -- (group c1r2.south);

代码：

\documentclass{standalone}

\usepackage{pgfplots}
\usepgfplotslibrary{groupplots,units}
\pgfplotsset{compat=1.11}
\begin{document}
\begin{tikzpicture}

\begin{groupplot}[
      group style = {group size=1 by 2, x descriptions at=edge bottom, vertical sep=0.2cm},
      ytick={0, 1.8},
      ymin=-3,
      ymax=3,
      xmin=0,
      xmax=3]

\nextgroupplot
\addplot {x};

\nextgroupplot[x unit=s]
\addplot {-x};

\end{groupplot}
\draw[thick,red]
(group c1r1.north) -- (group c1r2.south);
\draw[thick,blue]
([xshift=-11mm]group c1r1.north) -- ([xshift=-11mm]group c1r2.south);
\end{tikzpicture}
\end{document}