It is not clear to me what you mean by "expressions" in this context. Dimension names but be character strings -- see ?dimnames, which says:
"The dimnames of a matrix or array can be NULL or a list of the same length as dim(x). If a list, its components are either NULL or a character vector with positive length of the appropriate dimension of x. " If somehow you expect plotmath type drawn objects or R expression objects, then you are confused. If I am just misunderstanding what you want, then I am confused. -- Bert On Thu, Oct 4, 2012 at 7:27 AM, Hofert Jan Marius <[email protected]> wrote: > Hi, > > I would like to use the dim names of an array as labels in a plot. In the > case of character labels, this is no problem. However, if I would like to > pass expressions through array dim names, they only appear as character > labels in the plot and are not evaluated as expressions (see the minimal > example below). How can this be done? > > Cheers, > > Marius > > > require(grid) > > tau <- c(0.25, 0.75) > alpha <- c(0.95, 0.99, 0.999) > a <- array(1:6, dim=c(2,3), dimnames=list(tau=tau, alpha=alpha)) > > taulabs <- as.expression(lapply(tau, function(t) bquote(tau==.(t)))) > dimnames(a)$tau <- taulabs # does not create expressions > dimnames(a) # => no expressions > dimnames(a)$tau[[1]] <- taulabs[1] > dimnames(a)$tau[[2]] <- taulabs[2] > dimnames(a) # => now characters > > gl <- grid.layout(1, 2, default.units="inch", widths=c(2,2), heights=c(2,2)) > ## grid.show.layout(gl) > pushViewport(viewport(layout=gl)) > > pushViewport(viewport(layout.pos.row=1, layout.pos.col=1)) > grid.rect(gp=gpar(col=NA, fill="gray80")) > grid.text(dimnames(a)[["tau"]][1], x=0.5, y=0.5) > upViewport() > > pushViewport(viewport(layout.pos.row=1, layout.pos.col=2)) > grid.rect(gp=gpar(col=NA, fill="gray50")) > grid.text(dimnames(a)[["tau"]][2], x=0.5, y=0.5) > upViewport() > > ______________________________________________ > [email protected] 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. -- Bert Gunter Genentech Nonclinical Biostatistics Internal Contact Info: Phone: 467-7374 Website: http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm ______________________________________________ [email protected] 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.
