#data summary function
data_summary <- function(x) {
  m <- mean(x)
  ymin <- m-sd(x)
  ymax <- m+sd(x)
  return(c(y=m,ymin=ymin,ymax=ymax))
}


#tukeyHSD level letters
getTukeyletters <- function(HSD){
  
  Tukey.labels <- data.frame(letters = multcompLetters(HSD[[1]][,4])["Letters"]$Letters)
  Tukey.labels$names <- rownames(Tukey.labels)
  return(Tukey.labels)
  
}