Boxplots of a Variogram Cloud Object
DESCRIPTION:
Produces side by side boxplots from a variogram cloud object.
USAGE: 
boxplot.vgram.cloud(x, nint=20, group, style.bxp="att",
                    plot=T, ...)
REQUIRED ARGUMENTS:
x:
an object of class "vgram.cloud".
OPTIONAL ARGUMENTS:
nint:
an integer specifying the number of equal width intervals of x$distance to split up the x$gamma values. This is ignored if group is supplied.
group:
a vector of groups to split x$gamma into. There will be one boxplot drawn for each unique value of group. This must be the same length as x$gamma. If supplied, the value of nint is ignored.
style.bxp:
the style for the boxplots. See the boxplot help file for possible values. The default value of att draws better boxplots for a variogram cloud than the style used in the default boxplot function.
plot:
if TRUE, the boxplot will be produced; otherwise, the calculated summaries of the arguments are invisibly returned.
...:
other arguments to the default boxplot function can be supplied.

Graphical parameters may also be supplied as arguments to this function (see par). In addition, the high-level graphics arguments described under par and the arguments to title may be supplied to this function. However, boxplot will always use linear axes: the log and [xy]axt arguments are ignored.

VALUE:
if plot is TRUE, the function bxp is invoked with these components, plus optional width, varwidth, notch, and style (and associated parameters), to produce the plot. Note that bxp returns a vector of box centers.

if plot is FALSE, an invisible list with the components listed below:

stats:
matrix (of size 5 by the number of boxes) giving the upper extreme (excluding outliers), upper quartile, median, lower quartile, and lower extreme (excluding outliers) for each box. By default, anything farther than 1.5 times the Inter-Quartile Range is considered an outlier. See the Details section below and the range argument above.
n:
the number of observations in each group.
conf:
matrix (of size 2 by the number of boxes) giving approximate 95% confidence limits for the median. The limits are functions of the quartiles, so a few outliers have little effect on them.
out:
optional vector of outlying points (outliers). See the Details section below.
group:
vector giving the box to which each point in out belongs.
names:
names for each box.

SIDE EFFECTS:
If plot is TRUE, a plot is created on the current graphics device.
DETAILS:
This function is a method for the generic function boxplot for class "vgram.cloud". It can be invoked by calling boxplot for an object of the appropriate class, or directly by calling boxplot.vgram.cloud regardless of the class of the object.

By default, whiskers are drawn to the nearest value not beyond a standard span from the quartiles; points beyond (outliers) are drawn individually. Giving range=0 forces whiskers to the full data range. Any positive value of range multiplies the standard span by this amount. The standard span is 1.5*(Inter-Quartile Range).

REFERENCES:
Cressie, Noel. (1993). Statistics For Spatial Data, Revised Edition. Wiley, New York.
SEE ALSO:
boxplot , plot.vgram.cloud , variogram.cloud .
EXAMPLES: 
scallop.vgcld <- variogram.cloud(log(tcatch+1) ~ loc(long,lat),
     data=scallops)
boxplot(scallop.vgcld)