maia-util/es6/count_rows.js

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

import copy_point_set from './copy_point_set'
import sort_rows from './sort_rows'
import array_equals from './array_equals'
import array_approx_equals from './array_approx_equals'

/**
 * This function counts rows of the input `point_set`, weighted, if desired, by
 * values in `wght_idx`.
 *
 * @author Tom Collins and Christian Coulon
 * @comment 7th November 2015
 * @param {PointSet} point_set - A point set
 * @param {number} [wght_idx] - The dimension of each point that should be used
 * to weight the count. If left undefined, each occurrence of a point will
 * increment the count of that point by 1.
 * @return {Object} [PointSet, number[]] An array whose first element is a
 * {@link PointSet} (unique and lexicographically ascending version of the
 * input), and whose second element is a (possibly weighted) count of those
 * points in the input.
 *
 * @example
 *     var ps = [[64, 2], [65, 1], [67, 1], [67, 1]];
 * var w = 1;
 * count_rows(ps, w)
 * →
 * [
 *   [
 *     [64, 2], [65, 1], [67, 1]
 *   ],
 *   [
 *     2, // One occurrence of [64, 2] in input point set, with weight 2.
 *     1, // One occurrence of [65, 1] in input point set, with weight 1.
 *     2 // Two occurrences of [67, 1] in input point set, each with weight 1.
 *   ]
 * ]
 */
export default function count_rows(point_set, wght_idx, approx = false){
  // No check on point_set credentials at present...
  if (wght_idx !== undefined && wght_idx < point_set[0].length){
    // Make a copy of the point_set, where wght_idx values are in the final
    // dimension of each point.
    var arr = copy_point_set(point_set);
    var arr2 = [];
    for (let i = 0; i < arr.length; i++){
      var curr_rmv = point_set[i][wght_idx];
      // console.log('curr_rmv:');
      // console.log(curr_rmv);
      arr[i].splice(wght_idx, 1);
      // console.log('arr[i]:');
      // console.log(arr[i]);
      arr2.push(arr[i].concat([curr_rmv]));
    }
    // Sort the rows of a copy of the dataset.
    var E = sort_rows(arr2);
    var F = E[0];
    // var g = E[1];
    // Create a new variable that will contain the unique rows of the dataset.
    var k = point_set[0].length - 1;
    var U = [];
    // Create a new variable that will contain the count of each unique row in
    // the original dataset.
    var v = [];
    U[0] = F[0].slice(0, k);
    v[0] = F[0][k];
    var i = 1; // Increment over F and g.
    var j = 1; // Increment over U and v.
    while (i < point_set.length){
      if (approx){
        if (array_approx_equals(F[i].slice(0, k),F[i - 1].slice(0, k))){
          v[j - 1] = v[j - 1] + F[i][k];
        }
        else{
          U[j] = F[i].slice(0, k);
          v[j] = F[i][k];
          j++;
        }
      }
      else {
        if (array_equals(F[i].slice(0, k),F[i - 1].slice(0, k))){
          v[j - 1] = v[j - 1] + F[i][k];
        }
        else{
          U[j] = F[i].slice(0, k);
          v[j] = F[i][k];
          j++;
        }
      }
      i++;
    }
  }
  else{
    // Sort the rows of a copy of the dataset.
    var E = sort_rows(point_set);
    var F = E[0];
    // var g = E[1];
    // Create a new variable that will contain the unique rows of the dataset.
    var k = point_set[0].length;
    var U = [];
    // Create a new variable that will contain the count of each unique row in
    // the original dataset.
    var v = [];
    U[0] = F[0];
    v[0] = 1;
    var i = 1; // Increment over F and g.
    var j = 1; // Increment over U and v.
    while (i < point_set.length){
      if (approx){
        if (array_approx_equals(F[i],F[i - 1])){
          v[j - 1]++;
        }
        else{
          U[j] = F[i];
          v[j] = 1;
          j++;
        }
      }
      else {
        if (array_equals(F[i],F[i - 1])){
          v[j - 1]++;
        }
        else{
          U[j] = F[i];
          v[j] = 1;
          j++;
        }
      }
      i++;
    }
  }
  return [U.slice(0, j), v.slice(0, j)];
}