I would like to draw horizontal or vertical lines on a heatmap to highlight the clusters at some specified cut depth of the dendrogram. As a hacked example, the following code would work if I could set the coordinates of the top and bottom of the false color image correctly (ymin and ymax), but the correct values seem to depend on the output device and its size. I realize that heatmaps use a 2x2 layout which makes the coordinate system non-obvious, but the result seems very difficult to customize. I would appreciate any suggestions for manual or pre-made solutions.
Example: set.seed(2) x <- matrix(rnorm(1000),ncol=10) #obviously no real clusters here... row.hclust <- hclust(dist(x)) row.dendro <- as.dendrogram(row.hclust) heatmap(x, Rowv=row.dendro) row.cut <- cutree(row.hclust,3)[row.hclust$order] cutpoints <- which(row.cut[-1]!=row.cut[-length(row.cut)]) ymin <- par("usr")[3] #in general incorrect ymax <- par("usr")[4] #in general incorrect for (i in cutpoints){ thisy <- ymin + (ymax-ymin)*(i-1)/nrow(x) abline(h=thisy,lw=3) } ______________________________________________ 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.