maia-util/es6/group_grace_by_contiguous_id.js

Utility math and music functions supporting various applications by Music Artificial Intelligence Algorithms, Inc.

import sort_points_asc_by_id from './sort_points_asc_by_id'

export default function group_grace_by_contiguous_id(grace_array){
  // Tom Collins 18/2/2015.
  // In
  // grace_array Array mandatory
	// An array of grace notes is the input to this function. The function groups
  // these grace notes into new arrays whose membership is determined by
  // contiguity of the id fields. This is to make sure that if several grace
  // notes precede an ordinary note, these are grouped together and (later)
  // attached to this ordinary note.

  var ga = grace_array.sort(sort_points_asc_by_id);
  if (ga.length > 0){
    var gag = [[ga[0]]];
    var gj = 0;
    for (let gi = 1; gi < ga.length; gi++){
      if (parseFloat(ga[gi].ID) ==
          parseFloat(gag[gj][gag[gj].length - 1].ID) + 1){
        gag[gj].push(ga[gi]);
      }
      else{
        gag.push([ga[gi]]);
        gj++;
      }
    }
  }
  else{
    var gag = [];
  }
  return gag;
}