R Scale plot elements within PDF of set width and height

Question

Though R plots sent to a PDF can be rescaled at will in an illustration or page layout software, scientific journals often insist that the plots provided have specific dimension

Answer 1

Journals insist on having specific plot dimensions in order to avoid scaling. If made, it can render the font size too small (or large) and inconsistent with the figure caption font size. That is why the plot elements (text, point size, etc.) by design have the same absolute size regardless of pdf size.

You can change the default font size and point size, for example, with:

p <- ggplot(iris, aes(x=Petal.Width, y=Petal.Length, colour=Species)) +
  geom_point(size=1.5) +  # default is 2
  theme_grey(base_size=10)  # default is 12
ggsave("test.1.pdf", p)

The defaults can be changed globally, too:

update_geom_defaults("point", list(size=1.5))
theme_set(theme_grey(base_size=10))