[R] how to add a vertical line for each panel in a lattice dotplot with log scale?

[Deepayan Sarkar]

On Mon, Jun 11, 2012 at 1:10 PM, maxbre <mbressan at arpa.veneto.it> wrote:
> sorry but I can't close this thread with a viable solution other than the
> following one
> (i.e. by defining an user function to add line);
>
> I understand that the problem is related to the fact that:
> mean(log(.)) != log(mean(.)) is
> but for some reason I can't put all that in practice inside the
> panel.abline(...)
>
> I would appreciate if someone can show me how (sorry but at this point I
> must give up...),

I'm not sure why this is difficult. Once you realize that your problem
was in taking mean of the log-transformed values instead of the
original values, all you need to do is transform back to the original
scale, compute mean, and transform back.

dotplot(date_sampl_time_recs ~ lower_b_i | site, data=teq,
        scales = list(x = list(log=TRUE)),
        xscale.components = xscale.components.logpower,
        layout = c(5,1),
        panel = function(x,y,...) {
            panel.grid(h=53, v=-1, lty="dotted", col="gray")
            panel.dotplot(x,y,...)
            panel.abline(v = median(x), col.line="red", lty="dotted")
            panel.abline(v = log10(mean(10^x)), col.line="blue", lty="dotted")
        }
        )

-Deepayan

> thank you all for the help
>
>
> # code start
>
> addLine<- function(a=NULL, b=NULL, v = NULL, h = NULL, ..., once=F) {
>  tcL <- trellis.currentLayout()
>  k<-0
>  for(i in 1:nrow(tcL))
>    for(j in 1:ncol(tcL))
>      if (tcL[i,j] > 0) {
>        k<-k+1
>        trellis.focus("panel", j, i, highlight = FALSE)
>        if (once) panel.abline(a=a[k], b=b[k], v=v[k], h=h[k], ...) else
>          panel.abline(a=a, b=b, v=v, h=h, ...)
>        trellis.unfocus()
>      }
> }
>
>
>
> dotplot(date_sampl_time_recs ~ lower_b_i | site, data=teq,
>        scales=list(x=list(log=TRUE)),
>        xscale.components = xscale.components.logpower,
>        layout=c(5,1),
>        panel = function(x,y,...) {
>          panel.grid(h=53, v=-1, lty="dotted", col="gray")
>          panel.dotplot(x,y,...)
>          medians <- median(x)
>          panel.abline(v=medians, col.line="red", lty="dotted")
>          }
>        )
>
> medie<-as.vector(tapply(teq$lower_b_i,teq$site,mean))
>
> addLine(v=log10(medie), once=TRUE, col="blue", lty="dotted")
>
> # code end
>
>
>
>
> --
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>
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