Graphics, Figures & Tables

asmithb · Post by **asmithb** » Tue Feb 23, 2021 12:14 pm

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

NEW: TikZ book now 40% off at Amazon.com for a short time.

Bartman · Post by **Bartman** » Tue Feb 23, 2021 6:43 pm

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

asmithb · Post by **asmithb** » Thu Feb 25, 2021 10:27 am

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

Code: Select all

\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 · Post by **rais** » Fri Feb 26, 2021 7:44 pm

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

Code: Select all

\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

asmithb · Post by **asmithb** » Tue Mar 02, 2021 12:48 pm

Thank you very much!

I have one more question. How could I highlight the intersect area (originally filled in white color) with oblique lines or with other styles (not filled entirely with a color)?

How could I draw the intersect of the 3 circles A, B and C, instead of just A and B (as was done in your code).

Bartman · Post by **Bartman** » Tue Mar 02, 2021 3:53 pm

Read chapter 62 "Pattern Library".

Use the \clip command also for the node named NC before the \fill command within the scope environment.

asmithb · Post by **asmithb** » Thu Mar 04, 2021 11:21 am

Thank you for your reply. I have 2 more questions. IIn the following code, I want to keep the circle B lines intact (and the inner side of the intersection filled in white not blue) but do not know how to do it. In addition, I want to point the intersects of A and C, but do not know how to do it. Could you help me?

Code: Select all

\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] (-2,1.5) circle (1.4) 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 circles A and C:

\clip  (NA) circle (3);
%\clip  (NB) circle (1.4);
\clip  (NC) circle (3);


% 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 (3);
\fill[white] (NC) circle (3)% 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-3) circle (3pt) node[above=3pt]{SQ};
\end{scope}
 
\node at (-4,5.2) {\LARGE\textbf{X}};
\node at (-3,4) {\LARGE\textbf{A}};
\node at (-2,1.5) {\LARGE\textbf{B}};
\node at (-3,-4) {\LARGE\textbf{C}};
\node at (0,0) {\LARGE\textbf{0}};

\end{scope}
 
\draw[help lines](-5,5) grid (5,-6);
 
\end{tikzpicture}

rais · Post by **rais** » Sun Mar 07, 2021 7:20 pm

asmithb wrote:IIn the following code, I want to keep the circle B lines intact (and the inner side of the intersection filled in white not blue) but do not know how to do it.

You can do the same thing with circles B and C like I did with circles A and B.
Since I left the calculation for getting radius - half the line width as a comment in the code using the original 3 cm for the radius, it doesn't need a druid to replace 3 cm with 1.4 cm, does it?
On the other hand, you'd have to adapt the calculated values if you change the line width, e.g., to `thick' (0.8 pt). It may be more convenient if the line width could be disregarded completely---which it can, if the circles are drawn after all the clippings are done.

asmithb wrote:In addition, I want to point the intersects of A and C, but do not know how to do it.

Well, instead of or additionally to name intersections={of=A and B} you use name intersections={of=A and C}.
In the code below I used the name option to get AB-* (intersecting points A and B), AC-* (intersecting points A and C), and BC-* (intersecting points B and C).

asmithb wrote: \fill (intersection-3) circle (3pt) node[above=3pt]{SQ};

with circles you only get a third intersecting point if both circles have the same size and origin.

Code: Select all

\documentclass{article}

\usepackage{tikz}

\usetikzlibrary{intersections}

\begin{document}

\begin{tikzpicture}
\def\rA{3}% radius circle A
\def\rB{1.4}% radius circle B
\def\rC{3}% radius circle C
\begin{scope} [fill opacity = .4]

\draw (-5,5) rectangle (5,-6);
% name the paths:
\path[name path=A, fill=green] (-1.5,1) circle (\rA) node(NA){};
\path[name path=B, fill=blue] (-2,1.5) circle (\rB) node(NB){};
\path[name path=C, fill=red] (0,-2) circle (\rC) node(NC){};

\begin{scope}[fill opacity=1]% punch out the intersecting area of circles A and C:
\clip (NA) circle (\rA);
%\clip (NB) circle (\rB);
%\clip (NC) circle (\rC);
\fill[white] (NC) circle (\rC);%
\end{scope}% end the scope to be able to draw something outside its clip area

\begin{scope}[fill opacity=1]% intersecting area C / B:
\clip (NC) circle (\rC);
\fill[cyan] (NB) circle (\rB);
\end{scope}% same here

% get the intersection points between circles A and B:
\path[name intersections={of=A and B, name=AB}];
% get the intersection points between circles A and C:
\path[name intersections={of=A and C, name=AC}];
% get the intersection points between circles B and C:
\path[name intersections={of=B and C, name=BC}];
\begin{scope}[fill opacity=1]
%(re-)draw the circles:
\draw (NA) circle(\rA) (NB) circle (\rB) (NC) circle(\rC);
% put some solid dots at the intersecting points:
% since circle B does not intersect with circle A, there won't be any intersecting points (AB-*)
\fill (AC-1) circle (3pt) node[left=3pt]{SQ};
\fill (AC-2) circle (3pt) node[right=3pt]{SQ$'$};
\fill (BC-1) circle (3pt) +(0,-0.3) node[right]{SQ$''$};
\fill (BC-2) circle (3pt) +(0,-0.3) node[right]{SQ$'''$};
\end{scope}

\node at (-4,5.2) {\LARGE\textbf{X}};
\node at (-3,4) {\LARGE\textbf{A}};
\node at (-2,1.5) {\LARGE\textbf{B}};
\node at (-3,-4) {\LARGE\textbf{C}};
\node at (0,0) {\LARGE\textbf{0}};

\end{scope}

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

\end{tikzpicture}

\end{document}

KR
Rainer

asmithb · Post by **asmithb** » Mon Mar 08, 2021 12:10 pm

Thank you very much!

asmithb · Post by **asmithb** » Wed Mar 10, 2021 12:11 pm

Could you help me create a legend such as the one in the first image I shared (taken from the website)?

LaTeX.org

Graphics, Figures & Tables ⇒ Venn Diagrams and Intersection Points

Venn Diagrams and Intersection Points

Venn Diagrams and Intersection Points

Venn Diagrams and Intersection Points

Venn Diagrams and Intersection Points

Venn Diagrams and Intersection Points

Venn Diagrams and Intersection Points

Venn Diagrams and Intersection Points

Venn Diagrams and Intersection Points

Venn Diagrams and Intersection Points

Venn Diagrams and Intersection Points