二項分布と正規分布とポアソン分布のずれをアニメーションにする

gistfile1.r

s <- 100
index_h <- 500^(((1:s)-1)/(s-1))
index <- as.integer(c(index_h, rev(index_h)))
for (i in 1:length(index)) {
  png(sprintf("plot_%04d.png", i), width=500, height=500)
  np <- index[i]
  n <- 1000
  p <- np/n
  q <- 1 - p
  x <- 0:n
  xlim <- c(np-n*p*q -10,np+n*p*q +10)
  ylim <- c(0,max(dbinom(x, size=n, prob=p))*1.5)
  plot(dbinom(x, size=n, prob=p),          xlab="", ylab="", xlim=xlim, ylim=ylim, type="l", col="blue")
  par(new=T)
  plot(dnorm(x, mean=n*p, sd=sqrt(n*p*q)), xlab="", ylab="", xlim=xlim, ylim=ylim, type="l", col="green")
  par(new=T)
  plot(dpois(x, lambda=np),                xlab="", ylab="", xlim=xlim, ylim=ylim, type="l", col="red")

  legend("topleft", legend=c("dbinom", "dnorm", "dpois"), col=c("blue", "green", "red"), lty=1)
  text(np, 0, paste0("np=", np))
  
  dev.off()
}