Changing format of some axis labels in ggplot2 according to condition

Question

I have a ggplot and I want to highlight only some specific x-axis labels according to a predefined condition.

I know that axis text is controlled by

Answer 1

You can include for example ifelse() function inside element_text() to have different labels.

ggplot(iris,aes(Species,Petal.Length))+geom_boxplot()+
  theme(axis.text.x=
          element_text(face=ifelse(levels(iris$Species)=="setosa","bold","italic")))

Or you can provide vector of values inside element_text() the same length as number of levels.

ggplot(iris,aes(Species,Petal.Length))+geom_boxplot()+
 theme(axis.text.x = element_text(face=c("bold","italic","bold"),
                                   size=c(11,12,13)))