Hi all, I'm trying to plot error bars in a lattice plot generated with xyplot. Deepayan Sarkar has provided a very useful solution for simple circumstances (https://stat.ethz.ch/pipermail/r-help/2005-October/081571.html), yet I am having trouble getting it to work when the "groups" setting is enabled in xyplot (i.e. multiple lines). To illustrate this, consider the singer data generated by the above linked solution previously submitted:
##################### library(lattice) singer.split <- with(singer, split(height, voice.part)) singer.ucl <- sapply(singer.split, function(x) { st <- boxplot.stats(x) c(st$stats[3], st$conf) }) singer.ucl <- as.data.frame(t(singer.ucl)) names(singer.ucl) <- c("median", "lower", "upper") singer.ucl$voice.part <- factor(rownames(singer.ucl), levels = rownames(singer.ucl)) #now let's split up the voice.part factor into two factors, singer.ucl$voice=factor(rep(c(1,2),4)) singer.ucl$range=factor(rep(c("Bass","Tenor","Alto","Soprano"),each=2)) #here's Deepayan's previous solution, slightly modified to depict # the dependent variable (median) and the error bars on the y-axis # and the independent variable (voice.part) on the x-axis prepanel.ci <- function(x, y, ly, uy, subscripts, ...) { x <- as.numeric(x) ly <- as.numeric(ly[subscripts]) uy <- as.numeric(uy[subscripts]) list(ylim = range(y, uy, ly, finite = TRUE)) } panel.ci <- function(x, y, ly, uy, subscripts, pch = 16, ...) { x <- as.numeric(x) y <- as.numeric(y) ly <- as.numeric(ly[subscripts]) uy <- as.numeric(uy[subscripts]) panel.arrows(x, ly, x, uy, col = "black", length = 0.25, unit = "native", angle = 90, code = 3) panel.xyplot(x, y, pch = pch, ...) } #this graph works xyplot(median ~ voice.part, data=singer.ucl, ly = singer.ucl$lower, uy = singer.ucl$upper, prepanel = prepanel.ci, panel = panel.ci, type="b" ) #this one does not (it will plot, but will not seperate the groups) xyplot(median ~ voice, groups=range, data=singer.ucl, ly = singer.ucl$lower, uy = singer.ucl$upper, prepanel = prepanel.ci, panel = panel.ci, type="b" ) #################################### Any suggestions? -- Mike Lawrence [EMAIL PROTECTED] "The road to Wisdom? Well, it's plain and simple to express: Err and err and err again, but less and less and less." - Piet Hein ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html