[r] ggplot2: sorting a plot

I've recently been struggling with a related issue, discussed at length here: Order of legend entries in ggplot2 barplots with coord_flip() .

As it happens, the reason I had a hard time explaining my issue clearly, involved the relation between (the order of) factors and coord_flip(), as seems to be the case here.

I get the desired result by adding + xlim(rev(levels(x$variable))) to the ggplot statement:

ggplot(x, aes(x=variable,y=value)) + geom_bar() + 
scale_y_continuous("",formatter="percent") + coord_flip() 
+  xlim(rev(levels(x$variable)))

This reverses the order of factors as found in the original data frame in the x-axis, which will become the y-axis with coord_flip(). Notice that in this particular example, the variable also happen to be in alphabetical order, but specifying an arbitrary order of levels within xlim() should work in general.