Visualization of regression functions for two variables

Plot method for visualizing how two variables interact to affect the response in regression models.

Usage

# S3 method for class 'visreg2d'
plot(
  x,
  plot.type = c("image", "persp", "rgl", "gg"),
  xlab,
  ylab,
  zlab,
  color,
  print.cond = FALSE,
  whitespace = 0.2,
  ...
)

Arguments

x: A [visreg2d()] object.
plot.type: The style of plot to be produced. The following options are supported: * `image`: a filled contour * `gg`: a filled contour plot using ggplot2 * `persp`: a 3 dimensional perspective plot * `rgl`: a version of the perspective plot that can be rotated (requires the rgl package to be installed)
xlab: Axis label for x variable
ylab: Axis label for y variable
zlab: Axis label for outcome
color: For `plot.type='persp'` or `plot.type='rgl'`, the color of the surface. For `plot.type='image'` or `plot.type='gg'`, a vector of colors used to establish a color palette.
print.cond: 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.
whitespace: When `xvar` or `yvar` is a factor, `whitespace` determines the amount of space in between the factors. Default is 0.2, meaning that 20 percent of the axis is whitespace.
...: Graphical parameters can be passed to the function to customize the plots.

References

Breheny P and Burchett W. (2017) Visualization of regression models using visreg. *R Journal*, **9**: 56-71. doi:10.32614/RJ-2017-046

Author

Patrick Breheny and Woodrow Burchett

Examples

fit <- lm(Ozone ~ Solar.R + Wind + Temp + I(Wind^2) + I(Temp^2) +
I(Wind*Temp)+I(Wind*Temp^2) + I(Temp*Wind^2) + I(Temp^2*Wind^2),
data=airquality)

visreg2d(fit, x="Wind", y="Temp", plot.type="image")

visreg2d(fit, x="Wind", y="Temp", plot.type="image",
         color=c("purple", "green", "red"))

visreg2d(fit, x="Wind", y="Temp", plot.type="persp")


## Requires the rgl package
# \donttest{
visreg2d(fit,x="Wind",y="Temp",plot.type="rgl")
#> Loading required namespace: rgl
#> Warning: RGL: unable to open X11 display
#> Warning: 'rgl.init' failed, will use the null device.
#> See '?rgl.useNULL' for ways to avoid this warning.
# }

## Requires the ggplot2 package
# \donttest{
visreg2d(fit, x="Wind", y="Temp", plot.type="gg")

# }