Say, I have a GAM that looks like this:
# Load library
library(mgcv)
# Load data
data(mtcars)
# Model for mpg
mpg.gam <- gam(mpg ~ s(hp) + s(wt), data = mtcars)
Now, I'd like to plot the GAM using ggplot2. So, I use plot.gam to produce all the information I need, like this:
foo <- plot(mpg.gam)
This also generates an unwanted figure. (Yes, I realise that I'm complaining that a plotting function plots something...) When using visreg in the same way, I'd simply specify plot = FALSE to suppress the figure, but plot.gam doesn't seem to have this option. My first thought was perhaps invisible would do the job (e.g., invisible(foo <- plot(mpg.gam))), but that didn't seem to work. Is there an easy way of doing this without outputting the unwanted figure to file?
Okay, so I finally figured it out 5 minutes after posting this. There is an option to select which term to plot (e.g., select = 1 is the first term, select = 2 is the second), although the default behaviour is to plot all terms. If, however, I use select = 0 it doesn't plot anything and doesn't give an error, yet returns exactly the same information. Check it out:
# Load library
library(mgcv)
# Load data
data(mtcars)
# Model for mpg
mpg.gam <- gam(mpg ~ s(hp) + s(wt), data = mtcars)
# Produces figures for all terms
foo1 <- plot(mpg.gam)
# Doesn't produce figures
foo2 <- plot(mpg.gam, select = 0)
# Compare objects
identical(foo1, foo2)
[1] TRUE
Bonza!