[R] how to suppress whiskers in a bwplot?

[Uwe Ligges]

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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