Visualization of regression functions for two variables

Plot method for visualizing how two variables interact to affect the response in regression models, as a ggplot2 raster/contour plot.

Usage

# S3 method for class 'visreg2d'
plot(
  x,
  xlab = NULL,
  ylab = NULL,
  zlab = NULL,
  color,
  print_cond = FALSE,
  whitespace = 0.2,
  plot.type = NULL,
  ...
)

Arguments

x: A visreg2d() object.
xlab, ylab: Axis labels for predictors (default: variable name)
zlab: Label for the color legend (default: outcome variable name)
color: A vector of colors used to establish the color palette for the fill/legend.
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.
plot.type: Deprecated, no longer has any effect. See vignette.
...: Not used.

Value

A ggplot2 object.

Details

For 3-dimensional surface plots, see persp.visreg2d() (static) or rgl::persp3d() (interactive, requires the rgl package).

References

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

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")

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