Specify font family of labels at a time in ggplot2

While opts() offers the way to specify font family for each text element,
theme(base_family=…) enables to set the font family of all text elements at a time.
The “default” can be overwritten by opts().

 

sans default:

qplot(1:10, 1:10, label=letters[1:10], colour=1:10, geom="text", main="sans family") + theme_grey(base_family="sans")

 

serif default:

qplot(1:10, 1:10, label=letters[1:10], colour=1:10, geom="text", main="serif family") + theme_grey(base_family="serif")

 

serif default but xlab is sans

qplot(1:10, 1:10, label=letters[1:10], colour=1:10, geom="text", main="serif family") + theme_grey(base_family="serif") +
  xlab("here is sans") + opts(axis.title.x=theme_text(family="sans"))

 

Note that font family in geom_text() is determined via different way, so theme_*(base_family) has no effect on geom_text().