The
levelplot and
contourplot
functions are done by common code and differ only in the default
settings of the listed arguments.
The following arguments have special meaning within these functions.
The common meanings for these and all other arguments are listed separately
under
trellis.args.
ARGUMENTS:
formula
a formula, in general, its form is:
z ~ x * y | g1 * g2 * ...
The
z variable is a numeric response,
and
x and
y are the numeric predictors evaluated on a rectangular grid.
The given variables
g1,
g2 ,
... may be omitted.
at
values of
z for the contour lines or breaks between colored regions.
If
at is omitted, it is computed based on the
pretty flag:
if
pretty is
TRUE, the default for
at is
pretty(z,cuts) ;
if
pretty is
FALSE, the default is
seq(min(z),max(z),length=cuts+2) .
col.regions
numeric vector of color numbers used to color the regions between
contour lines.
colorkey
a logical flag or a list of arguments to be passed
to the
color.key function.
If
colorkey is
TRUE,
a color key is placed in the right margin on each page;
if
FALSE, no color key will be displayed.
By default, a color key is displayed if regions are colored, i.e.,
there is a color key on a level plot but not on a contour plot.
If
colorkey is a list
with a component named
space,
space for the color key will be reserved
on the appropriate side of the array of panels;
values for
space are
"top",
"bottom",
"left" , and
"right" .
See the documentation for
color.key for a full description of the other
components of the
colorkey= list.
contour
logical flag.
If
contour is TRUE, a set of labeled
contour lines will be drawn on the plot at the z-values of
at.
cuts
determines the number of levels the range of
z
will be divided into for generating the
at vector.
See the description of
at for details of how its default values are generated
from
cuts and
pretty.
labels
a logical flag,
a character vector of contour labels
or a list that
contains a character vector
along with graphical parameter vectors to control size, color, and font of
the labels.
If
labels is
FALSE, no labels are drawn on the contour lines.
Labels are drawn only if
contour is
TRUE.
pretty
logical, should the generated
at vector be made up of pretty
numbers (useful when labeling contours)?
region
logical flag; if
FALSE, the regions between the
contour lines will not be colored.
VALUE:
an object of class
trellis,
which is automatically plotted by
print.trellis.