子图中 TikZ 图片的对齐

Question

我使用 TikZ 制作了两个图形，我想将它们并排放置。这是在 MWE 中完成的：

\documentclass{memoir} 
\usepackage{graphicx}
\usepackage{tikz}
\newsubfloat{figure}

\begin{document}

\begin{figure}[htbp]
\centering
\subbottom[Convex set]{
    \begin{tikzpicture}
    \draw[rotate=-45,fill=gray!30] (0,0) ellipse (30pt and 45pt);
    \end{tikzpicture}
}
\hspace{1cm}
\subbottom[Non-convex set]{
    \begin{tikzpicture}
    \draw[fill=gray!30] (0,0) to [out=140,in=90] (-1,-1)
    to [out=-90,in=240] (0.8,-0.6)
    to [out=60,in=-60] (1.2,1.2)
    to [out=120,in=90] (0.3,0.7)
    to [out=-90,in=20] (0.3,0)
    to [out=200,in=-40] (0,0);
    \draw (-0.5,-0.5) -- (0.7,0.7);
    \fill (-0.5,-0.5) circle[radius=1.5pt];
    \fill (0.7,0.7) circle[radius=1.5pt];
    \end{tikzpicture}
}
\caption{Graphical interpretation of convex sets.}
\label{fig:convexSet}
\end{figure}

\end{document}

结果是：

问题在于子图的顶部、中心和底部均未对齐。如何解决？是什么原因导致这种错位？TikZ 坐标系使用错误？

Answer 1

我认为to路径使用了一些控制点来扩展第二个图形的边界框。您可以通过\draw (current bounding box.south east) rectangle (current bounding box.north west);在每个末尾添加来看到这一点tikzpicture，这将为您提供以下内容：

如您所见，第二个周围有一些额外的空白。我不知道如何自动修复此问题，但您可以使用以下命令手动设置边界框\useasboundingbox：

\documentclass{memoir} 
\usepackage{graphicx}
\usepackage{tikz}
\newsubfloat{figure}

\begin{document}

\begin{figure}[htbp]
\centering
\subbottom[Convex set]{
    \begin{tikzpicture}
    \draw[rotate=-45,fill=gray!30] (0,0) ellipse (30pt and 45pt);
    %\draw (current bounding box.south east) rectangle (current bounding box.north west);
    \end{tikzpicture}
}
\hspace{1cm}
\subbottom[Non-convex set]{
    \begin{tikzpicture}
    \useasboundingbox (-1,-1.35) rectangle (1.5,1.35); % values found by trial and error
    \draw[fill=gray!30] (0,0) to [out=140,in=90] (-1,-1)
    to [out=-90,in=240] (0.8,-0.6)
    to [out=60,in=-60] (1.2,1.2)
    to [out=120,in=90] (0.3,0.7)
    to [out=-90,in=20] (0.3,0)
    to [out=200,in=-40] (0,0);
    \draw (-0.5,-0.5) -- (0.7,0.7);
    \fill (-0.5,-0.5) circle[radius=1.5pt];
    \fill (0.7,0.7) circle[radius=1.5pt];
    %\draw (current bounding box.south east) rectangle (current bounding box.north west);
    \end{tikzpicture}
}
\caption{Graphical interpretation of convex sets.}
\label{fig:convexSet}
\end{figure}
\end{document}