使用 forest 或 Tikz 绘制重叠组

Question

我该如何绘制类似这样的图像（请原谅这张极其糟糕的 Paint 图像）

抱歉，我无法提供任何确切的代码，但我基本上不知道该怎么做。希望您能理解。提前谢谢。

Answer 1

为原帖者指明正确方向

\RequirePackage[dvipsnames]{xcolor}

\documentclass[tikz]{standalone}
\usetikzlibrary{automata,positioning,fit,backgrounds}
\tikzset{
    back/.style={circle, 
        inner sep=0.2cm,
        rounded corners=3mm},
}

\begin{document}
    \begin{tikzpicture}[
        circ/.style={shape=circle, minimum size=1cm, draw, fill=white, outer sep=+0pt},
        back/.style={circle, inner sep=0.2cm, rounded corners=3mm}
        ]
        \draw
                node[circ]         (A1) at (0,0) {A1}
                node[circ]         (A2) at (2,2) {A2}
                node[circ]        (A3)  at (3,4) {A3}
                node[circ]         (A4) at (2,5) {A4};
\begin{pgfonlayer}{background}
    \node [back, fill=black!10,
    fit=(A1) (A2),
    label={[xshift=-2mm]above left:{\tiny black circle}}] {};
    \node [back, fill=red!10, 
    fit=(A2) (A3) (A4),
    label={[xshift=-2mm]above right:{\tiny red circle}}] {};
\end{pgfonlayer}
                
    \end{tikzpicture}
\end{document}