When you choose a log scale, ggplot2 formats the breaks like 10^x. I'd like it to not do that. For example, the code below should display a graph with ticks at 1, 2, 5 etc, not 10^0, 10^0.3, 10^0.69 etc.

library(ggplot2)
dfr <- data.frame(x = 1:100, y = rlnorm(100))
breaks <- as.vector(c(1, 2, 5) %o% 10^(-1:1))
p1 <- ggplot(dfr, aes(x, y)) + geom_point() + scale_y_log10(breaks = breaks)
print(p1)

I guess that adding a formatter argument to scale_y_log10 would do the trick, but I'm not sure what to put in the argument, or where the options might be documented.