R help - Jun 2008 - Coloring Stripchart Points, or Better, Lattice Equivalent

Hi All.

I have the commands below to create a stripchart/plot.  I was hoping to
color the points in the plot by yr, and use a symbol that varied with resp.
However, the outcome makes it appear as though the point by point col and
pch data is not being passed properly.  Any suggestions?

And truthfully, I?d rather be doing this with Lattice, but I?ve tried
several variations of stripplot and can?t even get something with the
general layout of the stripchart version.

Thanks, Bryan
*************
Bryan Hanson
Professor of Chemistry & Biochemistry
DePauw University, Greencastle IN USA

index <- round(runif(100, 1, 100))
resp <- rbinom(100, 1, 0.5)
yr <- rep(c("2005", "2006"), 50)
all <- data.frame(index, resp, yr)
for (n in 1:length(all$index)) {
    if (all$yr[n] == 2005) {all$col[n] <- "red"}
    else {all$col[n] <- "blue"}
    }
for (n in 1:length(all$index)) {
    if (all$resp[n] == 1) {all$sym[n] <- 1}
    else {all$sym[n] <- 3}
    }
stripchart(all$index, method = "stack", ylim = c(0,10), col = all$col,
pch all$sym)

Below is a revised set of code that demonstrates my question a little more
clearly, I hope.

When plotting all the data (5th panel), col & sym don't seem to be
passed
correctly, as the (random) first value for col & sym are used for all points
(run the code, then run it again, you'll see how the 5th panel changes
depending upon col & sym for the first data point).  The 5th panel should
ideally be the "sum" of the 4 panels above, keeping col & sym
intact.

Also, I would rather have this in lattice or ggplot2, if anyone sees how to
convert it.

Thanks once again, several of you have made very useful suggestions off
list.  Bryan

samples <- 100 # must be even
index <- round(runif(samples, 1, 100)) # set up data
resp <- rbinom(samples, 1, 0.5)
yr <- rep(c("2005", "2006"), samples/2)
all <- data.frame(index, resp, yr)
all$sym <- ifelse(all$resp == 1, 1, 3)
all$col <- ifelse(all$yr == 2005, "red", "blue")
all$count <- rep(1, length(all$index))
all <- all[order(all$index, all$yr, all$resp),] # for easier inspection
row.names(all) <- c(1:samples) # for easier inspection

one <- all[(all$yr == 2005 & all$resp == 0),] # First 2005/0 at top
two <- all[(all$yr == 2005 & all$resp == 1),] # Then 2005/1
three <- all[(all$yr == 2006 & all$resp == 0),] # Now 2006/0
four <- all[(all$yr == 2006 & all$resp == 1),] # Finally 2006/1

par(mfrow = c(5, 1))
par(plt = c(0.1, 0.9, 0.25, 0.75))
stripchart(one$index, method = "stack", ylim = c(0,10), xlim =
c(1,100), col
= one$col, pch = one$sym)
mtext("2005/0", side = 3)
stripchart(two$index, method = "stack", ylim = c(0,10), xlim =
c(1,100), col
= two$col, pch = two$sym)
mtext("2005/1", side = 3)
stripchart(three$index, method = "stack", ylim = c(0,10), xlim =
c(1,100),
col = three$col, pch = three$sym)
mtext("2006/0", side = 3)
stripchart(four$index, method = "stack", ylim = c(0,10), xlim =
c(1,100),
col = four$col, pch = four$sym)
mtext("2006/1", side = 3)
stripchart(all$index, method = "stack", ylim = c(0,10), xlim =
c(1,100), col
= all$col, pch = all$sym)
mtext("col & sym always taken from 1st data point when all data is
plotted!", side = 3)