R/initialize_below.R

In shill1729/synthesizer: Synthesize sounds, melodies, chords, and stochastic compositions

#' Initialize a counterpoint above the cantus firmus
#'
#' @param cf the cantus firmus vector
#' @param mode the mode to compose in
#' @param root the root note in mod 127 the exercise is composed in
#'
#' @description {Initialize a counterpoint below the cantus firmus}
#' @return vector
#' @export initialize_below
initialize_below <- function(cf, mode, root)
{
  # Get length of cantus firmus in number of notes
  n <- length(cf)
  # Initialize counterpoint
  cpt <- matrix(0, nrow = n)
  # First note is either unison, or p8 below
  cpt[1] <- root-sample(c(0, 12), size = 1)
  # Last note is p8
  cpt[n] <- root-12
  if (mode %in% c("phrygian", "locrian")) {
    penultimate_step <- 2
  } else if (mode %in% c("ionian", "dorian", "lydian", "mixolydian",
                         "aeolian")) {
    penultimate_step <- 1
  }
  cpt[n - 1] <- cpt[n] - penultimate_step
  return(cpt)
}