Multi years calendar by R and ggplot2

gistfile1.r

library(ggplot2)

f <- function(y1, y2) {
	d <- seq.Date(as.Date(paste(y1, "-01-01", sep = "")), as.Date(paste(y2, "-12-31", sep = "")), "day")
	z <- data.frame(
  D = as.numeric(format(d, "%d")), 
  W = format(d, "%w"),
  M = as.numeric(format(d, "%m")),
  Y = format(d, "%Y"))
  
ggplot(z, aes(D, M, fill = W)) + 
  geom_tile(colour = "grey20", alpha = 0.75) + 
  facet_grid(Y~.) + 
  scale_y_continuous(trans = "reverse", breaks = 1:12) + 
  scale_fill_manual(values = c("skyblue", rep("white", 5), "aquamarine")) +
  opts(legend.position = "none", axis.title.x = theme_blank(), axis.title.y = theme_blank(), panel.margin = unit(0.1, "lines"))
  }
  
f(2012, 2015)