Plot Regression Terms for Huge Datasets
Description
Plots regression terms against their predictors, optionally with standard errors and partial residuals in a density plot.
Usage
1 2 3 4 5 6 7 8 9 10 11 12  itermplot(model, data = NULL, envir = environment(formula(model)),
partial.resid = FALSE, scale=0, pixs = 1,
zmax=NULL, ztransf = function(x) {x}, colramp = IDPcolorRamp,
terms = NULL, se = FALSE,
xlabs = NULL, ylabs = NULL, main = NULL,
col.term = "black", lwd.term = 2,
col.se = "gray", lty.se = 2, lwd.se = 1,
col.smth = "darkred", lty.smth = 2,
lwd.smth = 2, span.smth = 2/3,
ask = interactive() && nb.fig < n.tms &&
.Device != "postscript",
use.factor.levels = TRUE, smooth = NULL, ...)

Arguments
model 
Fitted model object 
data 
Data frame in which variables in model can be found 
envir 
Environment in which variables in model can be found 
partial.resid 
Logical; should partial residuals be plotted? 
scale 
A lower limit for the number of units covered by the
limits on the ‘y’ for each plot. The default is 
pixs 
Size of pixel in x and ydirection in [mm] on the plotting device. When x and y are numeric, pixels are square. When x and y are factors, pixels are no longer square. The pixels are enlarged in xdirection. 
zmax 
Maximum number of counts per pixel in the plot. When NULL, each scatter plot has its individual scale. If a number >= maximum number of counts per pixel is supplied, the scale will be identical for all scatter plots. The maximum number of counts per pixel is delivered by the return value. 
ztransf 
Function to transform the number of counts per pixel.
The user has to make sure that the transformed density lies in the
range [0,zmax], where zmax is any positive number (>=2). For
examples see 
colramp 
Color ramp to encode the number of counts within a pixel by color. 
terms 
Numeric. Which terms to plot (default NULL means all terms) 
se 
Logical. Plot pointwise standard errors? 
xlabs 
Vector of labels for the x axes 
ylabs 
Vector of labels for the y axes 
main 
Logical, or vector of main titles; if TRUE, the model's call is taken as main title, NULL or FALSE mean no titles. 
col.term, lwd.term 
Color and line width for the “term curve” 
col.se, lty.se, lwd.se 
Color, line type and line width for the “twicestandarderror curve” when se = TRUE. 
col.smth, lty.smth, lwd.smth 
Color, line type and line width for the smoothed curve 
span.smth 
Smoothing parameter f for 
ask 
Logical. Should user be asked before each plot? cf.

use.factor.levels 
Logical. Should xaxis ticks use factor levels or numbers for factor terms? 
smooth 
NULL or a function with the same arguments as

... 
Other graphical parameters 
Details
itermplot
is a modified version of
termplot
of R V2.3.1. Partial residuals are
displayed here as a density plot and is therfore especially suited for
models of huge datasets.
The model object must have a predict method that accepts type=terms,
eg glm in the base package, coxph and survreg in the survival
package.
For the partial.resid=TRUE option it must have a residuals method that
accepts type="partial", which lm
, glm
and
gam
do.
The data argument should rarely be needed, but in some cases termplot may be unable to reconstruct the original data frame. Using na.action=na.exclude makes these problems less likely.
Nothing sensible happens for interaction terms.
Value
Maximum number of counts per pixel found.
Author(s)
Rene Locher
See Also
termplot
.
Examples
1 2 3 4 5 6 7 8 9 10 11 12 13  r.lm < lm(Sepal.Length~Sepal.Width+Petal.Length+Petal.Width+Species,
data=iris)
par(mfrow=c(2,2),pty="s")
itermplot(r.lm, se = TRUE, partial.res=TRUE, lwd.term = 3,
lwd.se = 2, pixs = 2)
if (require(SwissAir)) {
data(AirQual)
r.lm < lm(log(ad.O3)~log(ad.NOx)+ad.T+ad.Td+ad.WS, data=AirQual)
par(mfrow=c(2,2),pty="s")
itermplot(r.lm, se = TRUE, partial.resid=TRUE, smooth=ipanel.smooth,
lwd.smth = 3, pixs = 1, ask=FALSE)
} else print("Package SwissAir is not available")
