preplot.gam
Object
preplot.gam
object.
gplot(x, y, se.y = NULL, xlab = "", ylab = "", residuals = NULL, rugplot = F, scale = 0, se = F, fit = T, ...)
x
variable for plotting
y
; can be
NULL
.
y
; can be
NULL
.
TRUE
, a
rugplot
is produced at the base of the plot
TRUE
, pointwise standard errors are included in the plot
TRUE
, plot a curve to the data.
This is a generic plotting function for representing fitted
gam
functions.
The type of function plot depends on the class of
x
.
Methods exists for several data classes.
The default behavior is to produce no plot and issue a warning.
If
x
is
numeric
, the function is represented by a polygon
connecting the fitted values
y
ordered by
x
.
If the class is
factor
, the values of
y
are constant within
each level of
x
, and the function is represented by a step-function.
If
x
is a
list
(with two numeric variables),
or
matrix
(2 column), the function is represented by a perspective surface.
gplot
is not called directly by users; rather,
it is called by
plot.preplot.gam
, the plot method
for
preplot.gam
objects. Such an object is a list of fitted terms,
each of which has components
x
,
y
,
se.y
, etc,
and
plot.preplot.gam
simply dispatches them as arguments to
gplot
.
Users will occasionally encounter examples where no
gplot
method
corresponding to the data class of
x
exists.
In this case, no plot is produced, and two possible avenues exist.
Either one can write a new
gplot
method for that particular class
which would then be available for all future encounters, or one could
simply construct a plot on a one time basis using the precomputed
data in the
preplot.gam
object.