svg("poisson-vs-binomial.svg", width=4, height=4)
x <- 0:10
pmean <- 5
pal <- c("black", "tomato", "royalblue", "darkgreen")
par0 <- par(mar=c(4,4,0.5,0)+0.5)
plot.new(); plot.window(range(x), c(0,max(dbinom(x, 10, pmean/10))))
axis(1); axis(2); title(xlab=expression(k), ylab=expression(Density(k)))
abline(h=0, lwd=0.1)
lines(x, dpois(x, pmean), type="h", lwd=2, col=pal[[1]])
for (i in 1:3) {
  n <- c(10, 20, 1000)[[i]]
  y <- dbinom(x, n, pmean/n)
  lines(x, y, type="b", col=pal[[i+1]], pch=NA, lty=3, lwd=0.5)
  points(x, y, col=pal[[i+1]], lwd=2)
}
legend("topright", expression(Poisson(lambda==5),
    Binom(n==10),Binom(n==20),Binom(n==1000)),
  lwd=2, lty=c(1,NA,NA,NA), pch=c(NA,1,1,1), col=pal, cex=0.6)
par(par0)
dev.off()