Color map of Poland for the New Year

To celebrate the New Year I decided to plot map of Poland in our national colors.

It was not so difficult using maps  package. Here is the result:

and the code I used to generate it:

library(maps)

x.mid <- function(x1, x2, y1, y2, y.mid) {

      x1 + ((x2 - x1) / (y2 - y1)) * (y.mid - y1)

}

poland <- map("world","poland", fill=T, col="#D4213D")

mid <- mean(poland$range[3:4])

upper <- poland$y > mid

cut1 <- which.max(diff(upper))

x.first <- x.mid(poland$x[cut1], poland$x[cut1 + 1],

                 poland$y[cut1], poland$y[cut1 + 1], mid)

cut2 <- which.min(diff(upper))

x.last <- x.mid(poland$x[cut2], poland$x[cut2 + 1],

                 poland$y[cut2], poland$y[cut2 + 1], mid)

                         

upperx <- c(x.first,poland$x[upper],x.last)

uppery <- c(mid, poland$y[upper], mid)

polygon(upperx, uppery, col="white")