cmpstr/dist/cjs/metric/Hamming.cjs

CmpStr is a lightweight, fast and well performing package for calculating string similarity

// CmpStr v3.2.2 build-bb61120-260311 by Paul Köhler @komed3 / MIT License
'use strict';

var Metric = require('./Metric.cjs');
var Errors = require('../utils/Errors.cjs');

class HammingDistance extends Metric.Metric {
  constructor(a, b, opt = {}) {
    super('hamming', a, b, opt, true);
  }
  compute(a, b, m, n, maxLen) {
    if (m !== n) {
      if (this.options.pad !== undefined) {
        if (m < maxLen) a = a.padEnd(maxLen, this.options.pad);
        if (n < maxLen) b = b.padEnd(maxLen, this.options.pad);
        m = n = maxLen;
      } else
        throw new Errors.CmpStrUsageError(
          `Strings must be of equal length for Hamming Distance, a=${m} and b=${n} given, ` +
            `use option.pad for automatic adjustment`,
          { a: m, b: n }
        );
    }
    let dist = 0;
    for (let i = 0; i < m; i++) if (a[i] !== b[i]) dist++;
    return {
      res: m === 0 ? 1 : Metric.Metric.clamp(1 - dist / m),
      raw: { dist }
    };
  }
}
Metric.MetricRegistry.add('hamming', HammingDistance);

exports.HammingDistance = HammingDistance;