ggplot: how to remove unused factor levels from a facet?

Question

The following code

d1 = data.frame(y=1:2,group=factor(c(\'A\',\'B\'), levels=c(\'A\',\'B\',\'C\')), fac = \'f1\')
d2 = data.frame(y=1:3,group=factor(c(\'A\',\'B\         


        

Answer 1

Setting scales = free in facet grid will do the trick:

facet_grid( ~ fac, scales = "free")