reordering geom_bar when using facet_wrap

ggplot2, r

Solution

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)

Problem

What I try to achieve is having the bars ordered by a given variable per panel. A simple example: ``` library(ggplot2) library(plyr) df <- data.frame(fac = c("a", "b", "c", "e", "b", "c", "d"), val = c(1, 2, 7, 4, 5, 3, 1), group = c(1, 1, 1, 1, 2, 2, 2)) p1 <- ggplot(df, aes(x = fac, y = val)) + geom_bar() + facet_wrap(~ group, scales = "free") + coord_flip() p1 p2 <- ggplot(df, aes(x = reorder(fac, val), y = val)) + geom_bar() + facet_wrap(~ group, scales = "free") + coord_flip() p2 ``` p2 does not produce what I want because not every "factor level" appears in all panels. Is there a simple solution already for this problem? One solution I found is the following (calculates the rank for each factor level per group). ``` df2 <- ddply(df, .(group), transform, fac2 = rank(val)) df2$fac2 <- factor(df2$fac2) p3 <- ggplot(df2, aes(x = fac2, y = val)) + facet_wrap(~ group, scales = "free") + geom_bar(stat = "identity") + coord_flip() + opts(panel.margin = unit(2, "lines")) p3 ``` I have to set the labels by my self here. One possible solution is the following (hard coded for this example): ``` grid.newpage() grob <- ggplotGrob(p3) object.path <- grid.ls(getGrob(grob, "axis.text.y", grep = TRUE, global = TRUE), print = FALSE)$name grob <- grid::editGrob(grob, object.path[1], label = c("ABDQ", "M", "A", "B")) grob <- grid::editGrob(grob, object.path[2], label = c("A", "B", "EEEEX")) grid.draw(grob) ``` But there is another problem. I have to set the panel.margin by my self now and it seems to be not possible to do this as I'm only able to set a "global" panel.margin and what I need is one for all 4 sides (or at least 2). Question 1: Is there a simple solution using reorder? Question 2: Is there a solution using scale_x_discrete to get the needed axis? Question 3: I wasn't able to find the needed grid object to manipulate the viewports for the panel.margins. Is there an easy way to manipulate the appropriate grid object? Any ideas?

Original source