Adding lines and labels in lattice barchart [R]

Question

Hi, I have two questions concerning customizing a barchart in lattice. I tried to add labels to the barchart respectively edit the scale, but my code doesn't work. What I'm doing wrong? There should be some values including "%".

The second question is how lines can be drawn between the top and the bottom of the plotting area behind the bars and located at the printed scale values. Thank you for any suggestions and help, Sebastian.

Here is the code:

library(lattice)
library(plyr)
data(postdoc, package="latticeExtra")
colnames(postdoc) <- c("Legendtext 1", "2", "3", "4", "5")
colors <- c(rgb(166,27,30,maxColorValue = 255),                             
        rgb(192,80,77,maxColorValue = 255),
        rgb(24,65,83,maxColorValue = 255),
        rgb(60,143,167,maxColorValue = 255),
        rgb(130,184,208,maxColorValue = 255))
colorset <- simpleTheme(col=colors,                                          
                    border="white")
data.p <- prop.table(postdoc, margin=1)
data <- data.p * 100
pl <- barchart(data,
           par.settings = colorset,                                      
           box.ratio = 1,                                                
           xlab = " ",                                                   
           panel = function(...) {   # Code for panel function by rcs (http://stackoverflow.com/questions/3220702/display-values-in-stacked-lattice-barchart-r) - thank you very much!
             panel.barchart(...) 
             tmp <- list(...)
             tmp <- data.frame(x=tmp$x, y=tmp$y)
             # calculate positions of text labels                        
             df <- ddply(tmp, .(y),
                         function(x) {
                           data.frame(x, pos=cumsum(x$x)-x$x/2)
                         })
             panel.text(x=df$pos, y=df$y,                                
                        label=sprintf("%.0f", df$x),                     
                        cex=0.7, col="white")
             panel.axis(side = c("bottom"),
                        at = list(0, 20, 50, 75, 100),
                        labels = list("0%", "25%", "50%", "75%", "100%"),
                        ticks = TRUE)       
           },
           auto.key=list(columns=5, space="bottom",                          
                         cex=0.8, size=1.4, adj=1,
                         between=0.2, between.colums=0.1, 
                         size = 1.3, points = FALSE, rectangles = TRUE))

Answer 1

Question 1: The following works for me (half=FALSE)

panel.axis(side=c("bottom"),
           at=c(0, 25, 50, 75, 100),
           labels=c("0%", "25%", "50%", "75%", "100%"),
           rot=0, half=FALSE, ticks=TRUE)

Question 2: Add a call to panel.grid (or panel.abline) before panel.barchart() in your panel function:

panel.grid(h=FALSE, v=-1)