node-nlp/test/classifiers/bayes-classifier.test.js

Library for NLU (Natural Language Understanding) done in Node.js

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const { BayesClassifier } = require('../../lib');

function getClassifier2() {
  const classifier = new BayesClassifier({});
  classifier.addObservation([1, 1, 1, 0, 0, 0], 'one');
  classifier.addObservation([1, 0, 1, 0, 0, 0], 'one');
  classifier.addObservation([1, 1, 1, 0, 0, 0], 'one');
  classifier.addObservation([1, 1, 1, 1, 0, 0], 'one');

  classifier.addObservation([0, 0, 0, 1, 1, 1], 'two');
  classifier.addObservation([0, 0, 0, 1, 0, 1], 'two');
  classifier.addObservation([0, 0, 0, 1, 1, 0], 'two');
  return classifier;
}

function addObservations3a(classifier) {
  classifier.addObservation([1, 1, 1, 0, 0, 0, 0, 0, 0], 'one');
  classifier.addObservation([1, 0, 1, 0, 0, 0, 0, 0, 0], 'one');
  classifier.addObservation([1, 1, 1, 0, 0, 0, 0, 0, 0], 'one');
  classifier.addObservation([0, 0, 0, 1, 1, 1, 0, 0, 0], 'two');
  classifier.addObservation([0, 0, 0, 1, 0, 1, 0, 0, 0], 'two');
  classifier.addObservation([0, 0, 0, 1, 1, 0, 0, 0, 0], 'two');
}

function addObservations3b(classifier) {
  classifier.addObservation([0, 0, 0, 0, 0, 0, 1, 1, 1], 'three');
  classifier.addObservation([0, 0, 0, 0, 0, 0, 1, 0, 1], 'three');
  classifier.addObservation([0, 0, 0, 0, 0, 0, 1, 1, 0], 'three');
}

function getClassifier3() {
  const classifier = new BayesClassifier({});
  addObservations3a(classifier);
  addObservations3b(classifier);
  return classifier;
}

describe('Get classifications', () => {
  test('Should get correct clasifications for basic examples', () => {
    const classifier = getClassifier2();
    const classifications1 = classifier.getClassifications([1, 1, 1, 0, 0, 0]);
    expect(classifications1).toHaveLength(2);
    expect(classifications1[0].label).toEqual('one');
    expect(classifications1[1].label).toEqual('two');
    const classifications2 = classifier.getClassifications([0, 0, 0, 0, 1, 1]);
    expect(classifications2).toHaveLength(2);
    expect(classifications2[0].label).toEqual('two');
    expect(classifications2[1].label).toEqual('one');
  });
  test('Should get correct clasifications for more complex examples', () => {
    const classifier = getClassifier3();
    const classifications1 = classifier.getClassifications([
      1,
      1,
      0,
      0,
      0,
      0,
      1,
      0,
      0,
    ]);
    expect(classifications1).toHaveLength(3);
    expect(classifications1[0].label).toEqual('one');
    const classifications2 = classifier.getClassifications([
      0,
      0,
      1,
      1,
      1,
      0,
      0,
      0,
      1,
    ]);
    expect(classifications2).toHaveLength(3);
    expect(classifications2[0].label).toEqual('two');
    const classifications3 = classifier.getClassifications([
      1,
      0,
      0,
      0,
      1,
      0,
      0,
      1,
      1,
    ]);
    expect(classifications3).toHaveLength(3);
    expect(classifications3[0].label).toEqual('three');
  });
  test('Smoothing can be changed', () => {
    const classifier = getClassifier3();
    classifier.setSmoothing(0.5);
    expect(classifier.smoothing).toEqual(0.5);
    const classifications1 = classifier.getClassifications([
      1,
      1,
      0,
      0,
      0,
      0,
      1,
      0,
      0,
    ]);
    expect(classifications1).toHaveLength(3);
    expect(classifications1[0].label).toEqual('one');
    const classifications2 = classifier.getClassifications([
      0,
      0,
      1,
      1,
      1,
      0,
      0,
      0,
      1,
    ]);
    expect(classifications2).toHaveLength(3);
    expect(classifications2[0].label).toEqual('two');
    const classifications3 = classifier.getClassifications([
      1,
      0,
      0,
      0,
      1,
      0,
      0,
      1,
      1,
    ]);
    expect(classifications3).toHaveLength(3);
    expect(classifications3[0].label).toEqual('three');
  });
});