The answer to your question is to use a minimal value > 0 for the
argument "coef" of bwplot() such as coef=10^(-10)
Unfortunately, there is a bug in R-2.0.1, lattice 0.10-14, which shows
negative length whiskers for positive values of "coef".
From ?bwplot:
library(lattice)
bwplot(voice.part ~ height, data = singer,
xlab = "Height (inches)", coef = 10^(-10))
[I'm CCing to Deepayan Sarkar, the maintainer of lattice.]
Uwe Ligges
Alexis J. Diamond wrote:
> dear R-help,
>
> i have looked carefully through the R-help archives for information on how
> to suppress whiskers in a bwplot. someone asked this question a while
> ago, but the answer he received is not available in the archives.
>
> but i did manage to get my hands on a panel function (called
> "my.panel") that is supposed to do this (the function is
reproduced at the
> end of the email, below). the problem is that i get an error message
> when i use it in the following way:
>
> ####
> data(singer)
>
> bwplot(voice.part ~ height, data=singer, xlab="Height (inches)",
> panel = "my.panel")
> ####
>
> ### the error message is:
>
> Error in segments(x1 = structure(c(NA, NA, NA, NA), .Names =
c("", "", :
> Argument "x0" is missing, with no default
>
> ###
>
> i don't know if the problem is this panel function, or how I am
> (mis)using it.
> (i've never used a homegrown lattice panel function before.)
>
> i realize that there is an excellent function in Hmisc that generates cool
> bwplots sans whiskers, but those plots are too fancy for my
> current needs.
>
> all i need are regular boxy bwplots without whiskers
> (or umbrellas, as i guess they're also called).
>
> as a quick fix, i've also tried changing the color of the whiskers to
the
> background color to make the whiskers invisible, but this doesn't work
> well when the whiskers perfectly align with the border of the box.
>
> thank you for your help,
>
> alexis diamond
> adiamond at fas.harvard.edu
>
>
> ### my.panel, the function that I've been told can suppress whiskers,
> ### when outline = F
>
> my.panel <- function(x, y, box.ratio = 1, font = box.dot$font, pch =
box.dot$pch,
> cex = box.dot$cex, col = box.dot$col, outline = T, ...)
> {
> ok <- !is.na(x) & !is.na(y)
> x <- x[ok]
> y <- y[ok]
> y.unique <- sort(unique(y))
> width <- box.ratio/(1 + box.ratio)
> w <- width/2
> e <- par("cxy")[1]
> for(Y in y.unique) {
> X <- x[y == Y]
> q <- quantile(X, c(0.75, 0.5, 0.25))
> iqr <- q[1] - q[3]
> d <- q[c(1, 3)] + c(1, -1) * 1.5 * iqr
> up.w <- max(X[X <= d[1]], q[1])
> lo.w <- min(X[X >= d[2]], q[3])
> outliers <- X[X < lo.w | X > up.w]
> X <- c(up.w, q, lo.w)
> median.value <- list(x = X[3], y = Y)
> Box <- list(x1 = X[c(2, 4, 4, 2)], y1 = Y + c( - w,
> - w, w, w), x2 = X[c(4, 4, 2, 2)], y2 = Y +
> c( - w, w, w, - w))
> e <- par("cxy")[1]
> e.l <- min(e, (X[4] - X[5])/2)
> # prevent lower staple ends from touching box
> e.u <- min(e, (X[1] - X[2])/2)
> # prevent upper staple ends from touching box
> staple.ends <- list(x1 = rep(c(X[5], max(X[1] - e.u,
> X[2])), 2), y1 = c(rep(Y - w, 2), rep(Y + w,
> 2)), x2 = rep(c(min(X[5] + e.l, X[4]), X[1]),
> 2), y2 = c(rep(Y - w, 2), rep(Y + w, 2)))
> staple.body <- list(x1 = X[c(1, 5)], y1 = rep(Y - w,
> 2), x2 = X[c(1, 5)], y2 = rep(Y + w, 2))
> dotted.line <- list(x1 = X[c(1, 4)], y1 = c(Y, Y),
> x2 = X[c(2, 5)], y2 = c(Y, Y))
> box.umbrella <- trellis.par.get("box.umbrella")
> box.dot <- trellis.par.get("box.dot")
> box.dot.par <- c(list(pch = pch, cex = cex, col = col,
> font = font), ...)
> do.call("segments", c(staple.ends, box.umbrella))
> do.call("segments", c(staple.body, box.umbrella))
> do.call("segments", c(dotted.line, box.umbrella))
> do.call("segments", c(Box, trellis.par.get(
> "box.rectangle")))
> do.call("points", c(median.value, box.dot.par))
> if(outline & length(outliers) > 0) {
> outliers <- list(x = outliers, y = rep(Y,
> length(outliers)))
> do.call("points", c(outliers, trellis.par.get(
> "plot.symbol"), cex = cex))
> }
> }
> }
>
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