Using facet_wrap and ggsave in a figure with many panels

Question

I'm trying to generate scatter plots of two variables for several values of a third categorical variable (around 350). Here's my current code:

my.plot <- ggplot(aes(x=first_variable, y=second_variable, color=fourth_variable), data=my.data) + 
           geom_point() +
           facet_wrap(~ third_variable, scales = 'free')
ggsave(filename='test_plot.jpg', plot=my.plot, width=20, height=20, units='in', limitsize=FALSE)

However, the saved figure has font that is too big in relation to a plot area that is skewed and compressed. Is there a way I can shrink each panel's entire contents, font and all, to avoid overlapping and get good plots in the saved file?

These are two samples of the figure.

Answer 1

You can try reducing the size of all of the text with something like + theme(text = element_text(size = 10)), or look through the elements of theme to set text sizes for more specific elements.