I'm making some illustrations and it would be convenient to automatically shade the overlapping portions of circles. These illustrations are for Social Choice theory, a field in political science and economics. I've wrestled together some examples so you can see what I mean, but have not mastered the "color overlapping sections" problem (as you will see):
http://pj.freefaculty.org/scraps/t-m15g.pdf The shaded area does not overlap perfectly, mainly because I isolated the points manually with locator(). Tedious! I've not found R functions just for this. Are there any packages? You can get an idea of the problem if you run, for example library(plotrix) example(draw.circle) See the red and the blue circles overlap? What's the best way to "shade in" that overlapping area. I don't have Mathematica anymore, but they seem to be able to do this more-or-less easily http://mathematica.stackexchange.com/questions/2554/how-to-plot-venn-diagrams-with-mathematica I want to make R do same ( or develop package to do it). I was under some pressure to get a graph finished that I linked to above. But I would not want to do it that way again. The shapes won't always be perfect circles, they may be ellipses or other convex shapes. But if I could understand the problem for circles, maybe I could solve for others. Do you have suggestions? I am considering this. Collect the co-ordiates from the circle points C1 <- draw.circle(3.5,7,0.8,border="blue",lty=2,lwd=2) C2 <- draw.circle(2.5,8,0.6,border="red",lty=3,lwd=3) Can I isolate the relevant arcs from C1 and C2? If I could, I'd join them Cjoin <- list(x = c(C1$x, C2$x), y = c(C1$y, C2$y)) And use that for plotting. pj -- Paul E. Johnson Professor, Political Science Assoc. Director 1541 Lilac Lane, Room 504 Center for Research Methods University of Kansas University of Kansas http://pj.freefaculty.org http://quant.ku.edu ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
