Lattice densityplot with semitransparent filled regions

Hello,

I'm doing some graphics for a paper and a need customize such with filled
region above the density curve. My attempts I get something very near what
I need, but I don't solve the problem of use semitransparent filled. Below
a minimal reproducible code. Someone has any idea?

require(lattice)

# toy data...
dt <- expand.grid(A=1:2, B=1:3, y=1:50)
dt$y <- rnorm(nrow(dt), dt$B, dt$A)

# regular plot...
densityplot(~y|B, groups=A, data=dt, plot.points="rug")

# the actual panel...
panel.densityplot

# so, I edit this...
my.panel.densityplot <-
function (x, darg = list(n = 30), plot.points = "jitter", ref = FALSE,
? ?groups = NULL, weights = NULL, jitter.amount = 0.01 *
diff(current.panel.limits()$ylim),
? ?type = "p", ..., identifier = "density")
{
? ?if (ref) {
? ? ? ?reference.line <- trellis.par.get("reference.line")
? ? ? ?panel.abline(h = 0, col = reference.line$col, lty =
reference.line$lty,
? ? ? ? ? ?lwd = reference.line$lwd, identifier = paste(identifier,
? ? ? ? ? ? ? ?"abline"))
? ?}
? ?if (!is.null(groups)) {
? ? ? ?panel.superpose(x, darg = darg, plot.points = plot.points,
? ? ? ? ? ?ref = FALSE, groups = groups, weights = weights,
? ? ? ? ? ?panel.groups = panel.densityplot, jitter.amount =
jitter.amount, # alterei para my.panel....
? ? ? ? ? ?type = type, ...)
? ?}
? ?else {
? ? ? ?switch(as.character(plot.points), `TRUE` = panel.xyplot(x = x,
? ? ? ? ? ?y = rep(0, length(x)), type = type, ..., identifier =
identifier),
? ? ? ? ? ?rug = panel.rug(x = x, start = 0, end = 0, x.units = c("npc",
? ? ? ? ? ? ? ?"native"), type = type, ..., identifier = paste(identifier,
? ? ? ? ? ? ? ?"rug")), jitter = panel.xyplot(x = x, y = jitter(rep(0,
? ? ? ? ? ? ? ?length(x)), amount = jitter.amount), type = type,
? ? ? ? ? ? ? ?..., identifier = identifier))
? ? ? ?density.fun <- function(x, weights, subscripts = TRUE,
? ? ? ? ? ?darg, ...) {
? ? ? ? ? ?do.call("density", c(list(x = x, weights =
weights[subscripts]),
? ? ? ? ? ? ? ?darg))
? ? ? ?}
? ? ? ?if (sum(!is.na(x)) > 1) {
? ? ? ? ? ?h <- density.fun(x = x, weights = weights, ..., darg = darg)
? ? ? ? ? ?lim <- current.panel.limits()$xlim
? ? ? ? ? ?id <- h$x > min(lim) & h$x < max(lim)
? ? ? ? ? ?panel.lines(x = h$x[id], y = h$y[id], ..., identifier =
identifier)
## line above was added
? ? ? ? ? ?panel.polygon(x=h$x[id], y = h$y[id], ..., identifier =
identifier, alpha=0.2)
? ? ? ?}
? ?}
}

# my customized plot, I want semitransparent colors
# and use the colors of trellis.par.set("superpose.polygon") to fill
densityplot(~y|B, groups=A, data=dt,
? ? ? ? ? ?plot.points="rug", col=2:3,
? ? ? ? ? ?panel=panel.superpose,
? ? ? ? ? ?panel.groups=my.panel.densityplot)

Thanks!
Walmes.

==========================================================================
Walmes Marques Zeviani
LEG (Laborat?rio de Estat?stica e Geoinforma??o, 25.450418 S, 49.231759 W)
Departamento de Estat?stica - Universidade Federal do Paran?
fone: (+55) 41 3361 3573
VoIP: (3361 3600) 1053 1173
e-mail: walmes at ufpr.br
twitter: @walmeszeviani
homepage: http://www.leg.ufpr.br/~walmes
linux user number: 531218
==========================================================================

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