The simplest way is to use clip(): > clip(0, 33, -1, 0) > polygon(ff,gg,col=2) > clip(0, 33, 0, 1) > polygon(ff,gg,col=4)
------------------------------------- David L Carlson Department of Anthropology Texas A&M University College Station, TX 77840-4352 -----Original Message----- From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On Behalf Of mamuash bukana Sent: Friday, February 28, 2014 9:11 AM To: r-help@r-project.org Subject: [R] Conditional polygon colouring Dear R users I want to paint parts of a polygon with different colours conditional to values of the variable. Example: f<-seq(1,33) g<-sin(f) i<-rep(0,33) ff<-c(f,rev(f)) gg<-c(g,rev(i)) plot(ff,gg,type="n") polygon(ff,gg,col=2) # but I wanted to plot areas below and above the x-axis with different colours. In this attempt, I tried the following: g2<-array(NA,33) for(j in 1:33){ g2[j]<-ifelse(g[j]<=0,0,g[j]) } gg2<-c(g2,i) plot(ff,gg,type="n") polygon(ff,gg,col=2) lines(polygon(ff,gg2,col=4)) # but in this plot there are many overlaps on the x-axis when 0 is substituted for negative g values. May someone suggest me how to plot the two regions (above and below x-axis) without affecting the actual plot region with different colours please? ______________________________________________ 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. ______________________________________________ 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.
