r - ggplot2 - bar plot with both stack and dodge

Question

I am trying to create a barplot using ggplot2 where I am stacking by one variable and dodging by another.

Here is an example data set:

df=data.frame(
  year=rep(c("2010","2011"),each=4),
  treatment=rep(c("Impact","Control")),
  type=rep(c("Phylum1","Phylum2"),each=2),
  total=sample(1:100,8))

I would like to create a barplot where x=treatment, y=total, the stacked variable is type and the dodged variable is year. Of course I can do one or the other:

ggplot(df,aes(y=total,x=treatment,fill=type))+geom_bar(position="dodge",stat="identity")

ggplot(df,aes(y=total,x=treatment,fill=year))+geom_bar(position="dodge",stat="identity")

But not both! Thanks to anyone who can provide advice.

Answer 1

Here's an alternative take using faceting instead of dodging:

ggplot(df, aes(x = year, y = total, fill = type)) +
    geom_bar(position = "stack", stat = "identity") +
    facet_wrap( ~ treatment)

With Tyler's suggested change: + theme(panel.margin = grid::unit(-1.25, "lines"))