A function for visualizing regression models quickly and easily.
Default plots contain a confidence band, prediction line, and partial
residuals. Factors, transformations, conditioning, interactions, and a
variety of other options are supported. The plot.visreg function
accepts a visreg or visregList object as calculated by
visreg and creates the plot.
# S3 method for visreg
plot(x, overlay=FALSE, print.cond=FALSE,
whitespace=0.2, partial=identical(x$meta$trans, I), band=TRUE,
rug=ifelse(partial, 0, 2), strip.names=is.numeric(x$fit[,x$meta$by]),
legend=TRUE, top=c('line', 'points'), gg=FALSE, line.par=NULL,
fill.par=NULL, points.par=NULL, ...)A visreg or visregList object; see
visreg.
When by is specified, by default separate panels are used to
display each cross-section. If overlay=TRUE, these
cross-sections are overlaid on top of each other in a single plot.
If print.cond=TRUE, the explanatory variable values
conditioned on in a conditional plot are printed to the console
(default: FALSE). If print.cond=TRUE and
type="contrast", the conditions will still be printed, but
they have no bearing on the plot unless interactions are present.
When xvar is a factor, whitespace determines the amount of
space in between factors on the x-axis. Default is 0.2, meaning
that 20 percent of the horizontal axis is whitespace.
If partial=TRUE (the default), partial residuals are shown on
the plot.
If band=TRUE (the default), confidence bands are shown on the
plot.
By default, partial residuals are plotted. Alternatively, a
rug may be plotted along the horizontal axis instead.
Setting rug=TRUE turns off partial residuals by default; if
one wants both to be plotted, both rug=TRUE and
partial=TRUE need to be specified. Two types of rug plots
are available. If rug=1 or rug=TRUE, then a basic rug
is drawn on the bottom. If rug=2, then separate rugs are
drawn on the top for observations with positive residuals and on the
bottom for observations with negative residuals. Such plots are
particularly useful in logistic regression (see examples).
When by=TRUE, strip.names=TRUE adds the name of the
by variable to the strip at the top of each panel. Default
is FALSE for factors and TRUE for numeric by
variables. strip.names can also be a character vector, in
which case it replaces the strip names altogether with values chosen
by the user.
For overlay plots, (overlay=TRUE), should visreg create a
legend? If legend=TRUE (the default), a legend is placed in
the top margin.
By default, the model fits 'line' are plotted on top of the
partial residuals; usually this is preferable, but it does run the
risk of obscuring certain residuals. To change this behavior and
plot the partial residuals on top, specify top='points'.
By default (gg=FALSE), visreg will use the
lattice package to render the plot if multiple panels are
required. If gg=TRUE, it will use the ggplot2 package
instead, provided that it is installed.
List of parameters (see par) to pass to
lines(...) when lines are drawn in the plots.
List of parameters (see par) to pass to
polygon(...) when shaded confidence regions are drawn in the
plots.
List of parameters (see par) to pass to
points(...) when partial residuals are drawn in the plots.
Graphical parameters can be passed to the function to customize the
plots. If by=TRUE, lattice parameters can be passed, such as
layout (see examples below).
Breheny, P. and Burchett, W. (2017), Visualizing regression models using visreg. https://journal.r-project.org/archive/2017/RJ-2017-046/index.html
http://pbreheny.github.io/visreg/options.html
visreg
visreg2d
visreg-faq
# NOT RUN {
fit <- lm(Ozone ~ Solar.R + Wind + Temp,data=airquality)
visreg(fit, "Wind", line=list(col="red"), points=list(cex=1, pch=1))
## Changing appearance
visreg(fit, "Wind", line=list(col="red"), points=list(cex=1, pch=1))
## See ?visreg and http://pbreheny.github.io/visreg for more examples
# }
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