LaTeX forum ⇒ Graphics, Figures & Tables ⇒ Venn Diagrams and Intersection Points

[asmithb]

Dear Community,

I want to graph some Venn diagrams and highlight some intersection points, as shown on this website: https://verfassungsblog.de/veto-players ... -part-1-2/

I have added the picture of the website I am interested in. I want to highlight point SQ and the point where A and B intersect. However, I only find codes to highlight the intersection areas (but not the points themselves) and to magnify the intersection points (though I am not interested in magnifying such points).

Thank you very much for your support

[Bartman]

If you use tikz for the drawing, the intersection points can be calculated. You can use the assigned names or choose them yourself.

[asmithb]

Could you please help me? So far I have just made the following Venn diagram and labeled the point SQ:

[\documentclass{article}


\usepackage{tikz}

\RequirePackage{xkeyval}
\RequirePackage{tikz}
\RequirePackage{etoolbox}


\usetikzlibrary{shapes,backgrounds, intersections}




\begin{document}


\begin{tikzpicture}

\begin{scope} [fill opacity = .4]

\draw (-5,5) rectangle (5,-6);

\draw[fill=green, draw = black] (-1.5,1) circle (3);
\draw[fill=blue, draw = black] (1.5,1) circle (3);
\draw[fill=red, draw = black] (0,-2) circle (3);

\begin{scope}
\clip \firstcircle;
\clip \secondcircle;
\draw[fill=white];
\end{scope}



\node at (-4,5.2) {\LARGE\textbf{X}};
\node at (-3,4) {\LARGE\textbf{A}};
\node at (3,4) {\LARGE\textbf{B}};
\node at (-3,-4) {\LARGE\textbf{C}};
\node at (0,0) {\LARGE\textbf{0}};
\node at (0,-1.5) {\small\textbf{SQ}};
\end{scope}

\draw[help lines](-5,5) grid (5,-6);

\end{tikzpicture}

\end{document}][/code]

[asmithb]

Could you please help me? So far I have just made the following Venn diagram and labeled the point SQ:

[\documentclass{article}


\usepackage{tikz}

\RequirePackage{xkeyval}
\RequirePackage{tikz}
\RequirePackage{etoolbox}


\usetikzlibrary{shapes,backgrounds, intersections}




\begin{document}


\begin{tikzpicture}

\begin{scope} [fill opacity = .4]

\draw (-5,5) rectangle (5,-6);

\draw[fill=green, draw = black] (-1.5,1) circle (3);
\draw[fill=blue, draw = black] (1.5,1) circle (3);
\draw[fill=red, draw = black] (0,-2) circle (3);

\begin{scope}
\clip \firstcircle;
\clip \secondcircle;
\draw[fill=white];
\end{scope}



\node at (-4,5.2) {\LARGE\textbf{X}};
\node at (-3,4) {\LARGE\textbf{A}};
\node at (3,4) {\LARGE\textbf{B}};
\node at (-3,-4) {\LARGE\textbf{C}};
\node at (0,0) {\LARGE\textbf{0}};
\node at (0,-1.5) {\small\textbf{SQ}};
\end{scope}

\draw[help lines](-5,5) grid (5,-6);

\end{tikzpicture}

\end{document}

[rais]

Your code errs out (neither \firstcircle nor \secondcircle is defined).
Perhaps something like this?

Code: [Select all] [Expand/Collapse] [Download] ({untitled.tex})

\documentclass{article}
 
\usepackage{tikz}
 
\usetikzlibrary{intersections}
 
\begin{document}
 
\begin{tikzpicture}
 
\begin{scope} [fill opacity = .4]
 
\draw (-5,5) rectangle (5,-6);
% name the paths:
\path[name path=A, draw, fill=green] (-1.5,1) circle (3) node(NA){};
\path[name path=B, draw, fill=blue] (1.5,1) circle (3) node(NB){};
\path[name path=C, draw, fill=red] (0,-2) circle (3) node(NC){};
\begin{scope}[fill opacity=1]% punch out the intersecting area of cicles A and B:
\clip (NB) circle (2.99297);% half the line width smaller than the circle's radius
% to keep the circle's line (B) intact.
% (= 3cm - 0.2pt * 2.54cm/in / 72.27pt/in)
\fill[white] (NA) circle (2.99297);% same here for circle A
\end{scope}% end the scope to be able to draw something outside its clip area
 
% get the intersection points between circles A and B:
\path[name intersections={of=A and B}];
\begin{scope}[fill opacity=1]% put some solid dots at the intersecting points:
\fill (intersection-1) circle (3pt) node[above]{$y$}; 
\fill (intersection-2) circle (3pt) node[below=3pt]{SQ};
\end{scope}
 
\node at (-4,5.2) {\LARGE\textbf{X}};
\node at (-3,4) {\LARGE\textbf{A}};
\node at (3,4) {\LARGE\textbf{B}};
\node at (-3,-4) {\LARGE\textbf{C}};
\node at (0,0) {\LARGE\textbf{0}};
\node at (0,-1.5) {\small\textbf{SQ}};
\end{scope}
 
\draw[help lines](-5,5) grid (5,-6);
 
\end{tikzpicture}
 
\end{document}

BTW: you should refrain from using \RequirePackage inside your document. That's more suited for packages / classes. Besides, \usepackage is even less to type

KR
Rainer