Is it possible to plot a two-set/disc Venn diagram with proportional discs and intersection without having to use the below "trial-and-error" code? In the example below the left disc has 6 elements (disc area = 6), the right disc has 4 elements (disc area = 4) and the intersection has 2 elements (area = 2)

a1 = 6;
a2 = 4;
a1capa2 = 2;
d = 1.21;
y1[x_] := Sqrt[a1/π - x^2]
y2[x_] := Sqrt[a2/π - (x - d)^2]
    {y1[x], -y1[x], y2[x], -y2[x]}, {x, -2, 4},
    AspectRatio -> Automatic, PlotStyle -> {Black}
x0 = x /. Solve[y1[x] == y2[x], x][[1]]
caparea = 2 (N[Integrate[y2[x], {x, d - Sqrt[a2/π], x0}]] +
    N[Integrate[y1[x], {x, x0, Sqrt[a1/π]}]]

Here I have to guess the distance $d$ between the discs in order to get the intersection area, caparea, to the requested 2. (It also give an imaginary reply, which I find odd.)

enter image description here

I'm looking for a solution where you only input the disc areas, and the intersection area and the distance $d$ is calculated and the graph plotted.

There are several other solutions for Venn diagrams but they all seem to have the same disc size.



1 Answer 1


You could use Region functionality instead. Your disks:

d1 = Disk[{0,0}, Sqrt[6/π]];
d2 = Disk[{d,0}, Sqrt[4/π]];

The intersection area:

area = Assuming[1 < d < 2, Area @ RegionIntersection[d1, d2]];
area //TeXForm

$\frac{-8 \sin ^{-1}\left(\frac{\pi d^2-2}{4 \sqrt{\pi } d}\right)+12 \sec ^{-1}\left(\frac{2 \sqrt{6 \pi } d}{\pi d^2+2}\right)-\sqrt{-\pi ^2 d^4+20 \pi d^2-4}+4 \pi }{2 \pi }$

Solving to find d:

sol = d /. First @ NSolve[area == 2 && 1 < d < 2, d]



Block[{d = sol},
    Graphics[{FaceForm[None], EdgeForm[Black], d1, d2}, Axes->True]

enter image description here


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