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

[David Winsemius]

On Jun 7, 2012, at 11:34 AM, maxbre wrote:

> a new session of R with the following sessionInfo()
>
>

Part of the confusion may be that you have reversed the colors for  
mean and median in two different examples. The other confusion may be  
that mean(log(.)) != log(mean(.))


> this is the code I run
>
> #start
>
> library(lattice); library(latticeExtra)
>
>
> #example with user function
>
> 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(variety ~ yield | site, data = barley,
>        scales=list(x=list(log=TRUE)),
>        layout = c(1,6),
>        panel = function(x,y,...) {
>          panel.dotplot(x,y,...)
>          median.values <- median(x)
>          panel.abline(v=median.values, col.line="red")
>        })
>
> mean.values<-tapply(barley$yield, barley$site, mean)
>
> addLine(v=log10(mean.values), once=TRUE, col="blue")
>
>
> # example with panel.abline
>
> dotplot(variety ~ yield | site, data = barley,
>        scales=list(x=list(log=TRUE)),
>        layout = c(1,6),
>        panel = function(x,y,...) {
>          panel.dotplot(x,y,...)
>          mean.values <- mean(x)   #omitted in second run
>          panel.abline(v=mean.values, col.line="red")   #omitted in  
> second
> run
>          median.values <- median(x)
>          panel.abline(v=median.values, col.line="blue")
>        })
>
> #end
>
> this are the two different results I’ve got:
>
> example with user defined function
> http://r.789695.n4.nabble.com/file/n4632706/example_with_user_function.png
>
> example with panel.abline
> http://r.789695.n4.nabble.com/file/n4632706/example_with_panel_abline.png
>
> and now I’m really confused of what I’m doing and seeing…
>
>
>
> --
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>
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David Winsemius, MD
West Hartford, CT