On Monday 26 July 2004 18:17, Dirk Eddelbuettel wrote: > I've been scrathing my head over this one. Suppose I have a > data.frame which maps to a 'n x k' lattice, and that one of those > cells is empty. > > An artificial example is generated by > > Q<-data.frame(x1=sample(c("A","B"),10,replace=TRUE), > x2=c("C", rep("D",9)), y=rnorm(10)) > > where by having only one obs. for the first level of the second > factor x2, we ensure that there won't be full combinations of x1 and > x2.
The empty cell is not the issue, rather it's the fact that the panel that gets the first observation (x2 = "C") has only that one single observation. So for that panel, sd(x, na.rm = TRUE) = NA, hence dnorm(<mesh points>, mean = <whatever>, sd = NA) eventually produces a bunch of NA's, which grid.lines tries to draw. grid.lines has known issues with NA's, and I would guess that's what causes the broken pdf. The good news is that there doesn't seem to be any problems in r-devel (possibly because grid handles NA's better now). The natural workaround for your code would be to skip the panel.mathdensity call unless length(x) > 1. Deepayan > This seems to trip panel.mathdensity(), but only when printing to > pdf, and I can't find a way to avoid it. Consider > > > stopifnot(require(lattice)) > stopifnot(require(grid)) > > pdf("testfile.pdf") > Q<-data.frame(x1=sample(c("A","B"),10,replace=TRUE), > x2=c("C", rep("D",9)), y=rnorm(10)) > print(histogram(~ y | x1+x2, data=Q, > panel = function(x, ...) { > if (length(x) > 0) { > panel.histogram(x, ...) > panel.mathdensity(dmath = dnorm, col = "black", > args = list(mean=mean(x, > na.rm=TRUE), sd=sd(x, na.rm=TRUE))) } > })) > dev.off() > > > where the resulting pdf file is broken if and only if the > panel.mathdensity call is present. Without it, it works. To the > screen, it works with and without -- but copying to pdf again breaks > the pdf file if > panel.mathdensity is used. > > It is possible that I am overlooking something simple -- or is it a > genuine bug? > > Platform is win2k, R version is 1.9.1. > > Thanks for any pointers, Dirk ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html