mathjs/lib/function/set/setSize.js

'use strict';

var flatten = require('../../utils/array').flatten;

function factory (type, config, load, typed) {
  var equal = load(require('../relational/equal'));
  var compareNatural = load(require('../relational/compareNatural'));
  
  /**
   * Count the number of elements of a (multi)set. When a second parameter is 'true', count only the unique values.
   * A multi-dimension array will be converted to a single-dimension array before the operation.
   *
   * Syntax:
   *
   *    math.setSize(set)
   *    math.setSize(set, unique)
   *
   * Examples:
   *
   *    math.setSize([1, 2, 2, 4]);          // returns 4
   *    math.setSize([1, 2, 2, 4], true);    // returns 3
   *
   * See also:
   *
   *    setUnion, setIntersect, setDifference
   *
   * @param {Array | Matrix}    a  A multiset
   * @return {number}            The number of elements of the (multi)set
   */
  var setSize = typed('setSize', {
    'Array | Matrix': function (a) {
      return Array.isArray(a) ? flatten(a).length : flatten(a.toArray()).length;
    },
    'Array | Matrix, boolean': function (a, unique) {
      if (unique === false || a.length === 0) {
        return Array.isArray(a) ? flatten(a).length : flatten(a.toArray()).length;
      }
      else {
        var b = flatten(Array.isArray(a) ? a : a.toArray()).sort(compareNatural);
        var count = 1;
        for (var i=1; i<b.length; i++) {
          if (!equal(b[i], b[i-1])) {
            count++;
          }
        }
        return count;
      }
    }
  });

  return setSize;
}

exports.name = 'setSize';
exports.factory = factory;