mathjs/lib/esm/function/set/setMultiplicity.js

import { flatten } from '../../utils/array.js';
import { factory } from '../../utils/factory.js';
var name = 'setMultiplicity';
var dependencies = ['typed', 'size', 'subset', 'compareNatural', 'Index'];
export var createSetMultiplicity = /* #__PURE__ */factory(name, dependencies, (_ref) => {
  var {
    typed,
    size,
    subset,
    compareNatural,
    Index
  } = _ref;

  /**
   * Count the multiplicity of an element in a multiset.
   * A multi-dimension array will be converted to a single-dimension array before the operation.
   *
   * Syntax:
   *
   *    math.setMultiplicity(element, set)
   *
   * Examples:
   *
   *    math.setMultiplicity(1, [1, 2, 2, 4])    // returns 1
   *    math.setMultiplicity(2, [1, 2, 2, 4])    // returns 2
   *
   * See also:
   *
   *    setDistinct, setSize
   *
   * @param {number | BigNumber | Fraction | Complex} e  An element in the multiset
   * @param {Array | Matrix}     a  A multiset
   * @return {number}            The number of how many times the multiset contains the element
   */
  return typed(name, {
    'number | BigNumber | Fraction | Complex, Array | Matrix': function numberBigNumberFractionComplexArrayMatrix(e, a) {
      if (subset(size(a), new Index(0)) === 0) {
        // if empty, return 0
        return 0;
      }

      var b = flatten(Array.isArray(a) ? a : a.toArray());
      var count = 0;

      for (var i = 0; i < b.length; i++) {
        if (compareNatural(b[i], e) === 0) {
          count++;
        }
      }

      return count;
    }
  });
});