# STATS 4CI3 January 30, 2019

# Generate from a mixture of Normals

rmixnorm <- function(n, p, mu, s) {
  # p is the vector of mixing proportions
  # mu is the vector of means
  # s is the vector of standard deviations
  
  K <- length(p)
  # I will use explicit recycling here
  if (length(mu)!=K){
    if (length(mu)>k) {
      warning(paste("Only first ",K,
                    " means used.", sep=""))
      mu <- mu[1:k]
    }
    else {
      if (length(mu)%%K>0) 
        warning("Length of p is not a multiple of 
                length of mu")
      mu <- rep(mu, length=K)
    }
  }
  if (length(s)!=K){
    if (length(s)>k) {
      warning(paste("Only first ",K,
                     " sds used.", sep=""))
      s <- s[1:k]
    }
    else {
      if (length(s)%%K!=0) 
          warning("Length of p is not a multiple of 
                  length of s")
      s <- rep(s, length=K)
    }
  }
  Z <- sample(K, n, prob=p, replace=T)
  rnorm(n, mu[Z], s[Z])
}