<code>

ordered(c('A','B','AB','O'),levels=c('A','B','AB','O'))->todo
as.integer(todo)->todo

binary<-function(p_number,n=3) {
  bsum<-0
  bexp<-1
  while (p_number > 0) {
     digit<-p_number %% 2
     p_number<-floor(p_number / 2)
     bsum<-bsum + digit * bexp
     bexp<-bexp * 10
  }
n<-max(n,nchar(bsum))
sprintf(paste0("%0",n,"d"),bsum)
}

sapply(todo, binary)


</code>