Hi, I have a hard time in drawing circle on PCA. I have 60 samples. The corresponding PC1 scores and PC2 scores were stored as "mergedata". Here are the summary of PCs scores.
> range(mergedata[,"PC1"]) [1] 0.0085 0.0100 > range(mergedata[,"PC2"]) [1] 0.0032 0.0075 > mean(mergedata[,"PC1"]) [1] 0.009241667 > mean(mergedata[,"PC2"]) [1] 0.005541667 > dim(mergedata) [1] 60 102 First of all, I need to find the center of the cluster points in PC plot. Then, I would lilke to draw out from that center concentric circles with radius 1 SD, 1.5 SD, 2 SD, 2.5 SD and 3 SD. plot(mergedata[,"PC1"],mergedata[,"PC2"],xlab="PC1",ylab="PC2",xlim=range(mergedata[,"PC1"]),ylim=range(mergedata[,"PC2"]),pch=20,col="blue") ####circle with radius 1SD symbols(mean(mergedata[,"PC1"]),mean(mergedata[,"PC2"]),circle=sd(c(mergedata[,"PC2"],mergedata[,"PC1"])),inches=FALSE,add=TRUE) However, only points were plotted, but the cicle doesn't appear. Could anyone tell me what's wrong with my code? Thanks, Phoebe [[alternative HTML version deleted]] ______________________________________________ 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.