Question

I have been working on Venn Diagrams in GNU R. I have tried using the packages venneuler and VennDiagram. I find that VennDiagram has a lot more granular control, but it seems to lack the documentation to fill in all the details. The closest I can find is this PPT file.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3041657/bin/1471-2105-12-35-S4.PPT which I found from the URL: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3041657/

Here are my issues with using VennDiagram.

For the code

require(VennDiagram)
venn.diagram(list(B = 1:2000, A = 200:400),fill = c("yellow", "blue"), 
alpha = c(0.8, 0.8), cex =1.5, cat.pos=0, cat.fontface = 4,
lty = 1, fontfamily =3, filename = "test001.jpeg");

(I had an image here, but since I am new I do not have rights to post the image. Please generate the image from the code above.)

I can make a subset (hence a circle within a circle). But I am not finding a way to do the following:

1. Make BC to show as the equal of B^C. No, a literal “B^C” does not work. I would think there is a way to relabel the sets in a different property, but I have not seen a way to do it.
2. To position the labels of B^C and A^C within the sets and not on the outside as currently shown. I tried cat.pos=”inner” but that way not a valid property. I also tried cat.pos=c(0,0) in the hope that I could feed it as an X,Y where X & Y are from the center of the circle, but it did not produce any different results.

---

Thanks to DWin, here is the code to complete my diagram to the exercise.
Suppose that A ⊂ B. Show that B^c ⊂ A^c.

require(VennDiagram)
plot.new()
venn.plot <- venn.diagram(
x = list(B = 1:200, A = 20:40), category.names= expression(B, A), 
          fill = c("yellow", "blue"), alpha = c(0.8, 0.8), cex =1.5, 
          cat.pos=0, cat.dist=c(-.1, -.1),  filename = NULL) ;
grid.draw(venn.plot); # grid graphic requires explicit print or draw operation
grid.text(expression(B^c),x=0.2,y=0.95)
grid.text(expression(A^c),x=0.16,y=0.95)
grid.text(expression(A^c),x=0.16,y=0.75)

Answer 1

Perhaps something like this:

 venn.diagram(list(B = 1:200, A = 20:40), category.names= expression(B^c, A), 
            fill = c("yellow", "blue"), alpha = c(0.8, 0.8), cex =1.5, cat.pos=0, 
            cat.dist=c(.1, -.1), cat.fontface = 4,lty = 1, fontfamily =3,
            filename = "test001.jpeg")

To get the labels inside the circles, supply ‘cat.dist’ with negative values. The trick is that the reference point is radial distance from the boundary at 12 o’clock rather than from the center. The documentation says that the category.names argument is interpreted with plotmath syntax. The superscript operation in plotmath is done with the “^” operator. I have here moved the A” inside while leaving the B^c outside to suggest that it is the area outside the B circle that is being labeled. (I also improved the plotting time by making the example smaller.) I tried drawing three labels but that does not seem to “part of the package”.

Here’s a way you can annotate with grid.text() on the screen device:

plot.new()
venn.plot <- venn.diagram(
 x = list(B = 1:200, A = 20:40), category.names= expression(B^c, A), 
          fill = c("yellow", "blue"), alpha = c(0.8, 0.8), cex =1.5, 
          cat.pos=0, cat.dist=c(.05, -.1),  filename = NULL) ;
 grid.draw(venn.plot); # grid graphic requires explicit print or draw operation
 grid.text("B",x=0.8)
# then you can save to file