reordering geom_bar when using facet_wrap

Question

What I try to achieve is having the bars ordered by a given variable per panel.

A simple example:

    library(ggplot2)
    library(plyr)

    df <         


        

Answer 1

I think that grid.arrange is a much better tool for this than trying to shoehorn free scales into a faceting framework:

library(gridExtra)
q1 <- ggplot(subset(df,group == 1),aes(x = reorder(fac,val),y = val)) + 
        geom_bar() + 
        facet_wrap(~group) + 
        coord_flip()

q2 <- q1 %+% subset(df,group == 2)

grid.arrange(q1,q2,nrow = 1)