Adding text to panels in lattice barchart

Question

I try to add labels to bars in a lattice barchart with multiple panels. I end up with way too many labels (every label is in every panel).

Here is my code:

Answer 1

The underlying question here is how to add labels to a stacked barchart in lattice. The answer is provided in this question, but since the linked answer doesn't have multiple panels, I recreate a simpler answer using base R here:

You have to modify the panel function as follows:

• Calculate the cumulative sum of x values for each y value
• This is a classic split, apply, combine problem. You can use plyr for this (as in the linked answer), or, as I illustrate, split and do.call:

xx <- do.call(c, unname(lapply(split(x, y), function(t)cumsum(t)-t/2)))

The code:

barchart( 1:10 ~ Petal.Width + Petal.Length | Species, 
          data = iris[c(1:10, 51:60, 101:110), ], 
          stack = TRUE,
          panel=function(x, y, ...) {
            panel.barchart(x, y, ...)
            xx <- do.call(c, unname(lapply(split(x, y), function(t)cumsum(t)-t/2)))
            ltext(xx, y=y, labels=x)
         }
)