knn.test.js

import kNN from '../kNN';

describe('kNN', () => {
  it('should throw an error on invalid data', () => {
    expect(() => {
      kNN();
    }).toThrowError('Either dataSet or labels or toClassify were not set');
  });

  it('should throw an error on invalid labels', () => {
    const noLabels = () => {
      kNN([[1, 1]]);
    };
    expect(noLabels).toThrowError('Either dataSet or labels or toClassify were not set');
  });

  it('should throw an error on not giving classification vector', () => {
    const noClassification = () => {
      kNN([[1, 1]], [1]);
    };
    expect(noClassification).toThrowError('Either dataSet or labels or toClassify were not set');
  });

  it('should throw an error on not giving classification vector', () => {
    const inconsistent = () => {
      kNN([[1, 1]], [1], [1]);
    };
    expect(inconsistent).toThrowError('Matrices have different shapes');
  });

  it('should find the nearest neighbour', () => {
    let dataSet;
    let labels;
    let toClassify;
    let expectedClass;

    dataSet = [[1, 1], [2, 2]];
    labels = [1, 2];
    toClassify = [1, 1];
    expectedClass = 1;
    expect(kNN(dataSet, labels, toClassify)).toBe(expectedClass);

    dataSet = [[1, 1], [6, 2], [3, 3], [4, 5], [9, 2], [2, 4], [8, 7]];
    labels = [1, 2, 1, 2, 1, 2, 1];
    toClassify = [1.25, 1.25];
    expectedClass = 1;
    expect(kNN(dataSet, labels, toClassify)).toBe(expectedClass);

    dataSet = [[1, 1], [6, 2], [3, 3], [4, 5], [9, 2], [2, 4], [8, 7]];
    labels = [1, 2, 1, 2, 1, 2, 1];
    toClassify = [1.25, 1.25];
    expectedClass = 2;
    expect(kNN(dataSet, labels, toClassify, 5)).toBe(expectedClass);
  });

  it('should find the nearest neighbour with equal distances', () => {
    const dataSet = [[0, 0], [1, 1], [0, 2]];
    const labels = [1, 3, 3];
    const toClassify = [0, 1];
    const expectedClass = 3;
    expect(kNN(dataSet, labels, toClassify)).toBe(expectedClass);
  });

  it('should find the nearest neighbour in 3D space', () => {
    const dataSet = [[0, 0, 0], [0, 1, 1], [0, 0, 2]];
    const labels = [1, 3, 3];
    const toClassify = [0, 0, 1];
    const expectedClass = 3;
    expect(kNN(dataSet, labels, toClassify)).toBe(expectedClass);
  });
});