maia-util/dist/intersection.js

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

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = intersection;

var _lex_less_or_equal = require('./lex_less_or_equal');

var _lex_less_or_equal2 = _interopRequireDefault(_lex_less_or_equal);

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

/**
 * This function returns the intersection of two multidimensional numeric,
 * arrays, assuming both are already in increasing lexicographic order to
 * achieve O(n) computational complexity.
 *
 * @author Tom Collins
 * @comment 30th June 2022
 * @param {number[]} arr0 - An array.
 * @param {number[]} arr1 - An array.
 * @param {(boolean|number)} index - Indicates whether and which indices to
 * record as belonging to the intersection. Takes value 0 if recording indices
 * from arr0; value 1 if recording indices from arr0; true if recording indices
 * from both; and false otherwise.
 * @return {number[]} An array.
 *
 * @example
 *     intersection([[1, 4], [2, -2]], [[-2, 3], [2, -2], [4, 1]])
 * →
 * [[2, -2]]
 */
function intersection(arr0, arr1) {
  var index = arguments.length > 2 && arguments[2] !== undefined ? arguments[2] : false;

  var ans = [];
  var indices = void 0;
  if (index === 0 || index === 1 || index) {
    indices = [];
  }
  var i = 0; // Counter for arr0.
  var j = 0; // Counter for arr1.
  while (i < arr0.length && j < arr1.length) {
    // console.log("i:", i, "j:", j)
    var c = (0, _lex_less_or_equal2.default)(arr0[i], arr1[j]);
    // console.log("c:", c)
    if (c < 0) {
      j++;
    } else if (c > 0) {
      i++;
    } else {
      ans.push(arr0[i]);
      // Handle recording of indices.
      if (index === 0) {
        indices.push(i);
      } else if (index === 1) {
        indices.push(j);
      } else if (index) {
        indices[0].push(i);
        indices[1].push(j);
      }
      i++;
      j++;
    }
  }
  if (index === 0 || index === 1 || index) {
    return [ans, indices];
  } else {
    return ans;
  }
}