lattice : using both strip and strip.left

Dear all,


I'm routinely using lattice and ggplot2, I wish to create a lattice theme
that looks not too dissimilar to ggplot's defaults so I can include both
graphs in a document with a consistent look.

To illustrate my questions, consider the following example:

library(ggplot2)
library(lattice)

# example data
x <- seq(0, 10, len = 100)
y1 <- jitter(sin(x), 1000)
y2 <- 0.5*jitter(cos(x), 1000)

df <- melt( data.frame(x=x, one=y1, two=y2, condition1=factor(c("a",
"b")), condition2=factor(c("1","1", "2", "2"))),
                       id=c("x", "condition1", "condition2"))

# custom colors
myColors <- c( "#E41A1C", "#377EB8")

# here is the ggplot2 version
p <- qplot(x,value, data=df, facets = condition1 ~ condition2,
colour=variable)
p <- p + scale_colour_manual(values = myColors)
print(p)

# lattice version
lattice.options(default.theme = canonical.theme(color = T))
trellis.par.set("strip.border" = list(col="white"))
trellis.par.set("background" = list(col="white"))
trellis.par.set("axis.line" = list(col="darkgrey"))
trellis.par.set("strip.background" = list(col="darkgrey"))
trellis.par.set("plot.symbol" = list(col = myColors, pch=16, cex=0.8))


p2 <- xyplot(value ~ x | condition1 + condition2, data=df, groups =
variable,
       strip=strip.custom(which.given=1),
strip.left=strip.custom(which.given=2)  ,
      panel = function(x, y, ...) {
               panel.fill(grey(0.95), border="white")
               panel.grid(h=-1, v=-1, col="white", col.line="white",
lty=1, lwd=2.5)
        lpoints(x, y, pch=16, col=1:2, cex=1)
      },
 key = simpleKey(levels(df$variable), space = "right"))

print(p2)

Several things resist me, I welcome any input,

- with two levels of facetting, i often find convenient to layout the graphs
in a 2d, rectangular matrix, and have vertical and horizontal strips as in
ggplot2. Using strip and strip.left as in the example above leaves some
blanks where the other strip is expected. Can this be tuned?

- in addition to the main grid, I'd like to set a finer, secondary grid,
that subdivides it in halves. I can't find how to do this using panel.grid

- the axes should be white, but trellis.par.set("axis.line" =
list(col="white")) removes the tick marks altogether. Is there a way to get
rid off the line but keep the tick marks? There is a new setting for this in
base graphics, I guess there must be one in lattice with an appropriate call
to grid?

- to clip the background color to the plotting region as opposed to the
whole page, I use panel.fill, maybe there's a better way (a setting outside
the plotting function)?