MarkovMatrix-test.js

import expect from 'expect';
import { countByFrom, probablize } from 'src/MarkovMatrix';

describe('MarkovMatrix', () => {
  it('counts by from-state', () => {
    const input = [
      ['foo', 'bar'],
      ['foo', 'bar'],
      ['foo', 'bar'],
      ['foo', 'baz'],
      ['bar', 'baz'],
      ['bar', 'foo'],
      ['baz', 'bar'],
    ];

    const expected = {
      foo: {
        bar: 3,
        baz: 1,
      },
      bar: {
        foo: 1,
        baz: 1,
      },
      baz: {
        bar: 1,
      },
    };

    expect(countByFrom(input)).toEqual(expected);
  });

  it('probablizes from counts', () => {
    const input = {
      foo: {
        bar: 3,
        baz: 1,
      },
      bar: {
        foo: 1,
        baz: 1,
      },
      baz: {
        bar: 1,
      },
    };
    const expected = {
      foo: {
        bar: 0.75,
        baz: 0.25,
      },
      bar: {
        foo: 0.5,
        baz: 0.5,
      },
      baz: {
        bar: 1,
      },
    };

    expect(probablize(input)).toEqual(expected);
  });

  it('does the whole shebang', () => {
    const input = [
      ['foo', 'bar'],
      ['foo', 'bar'],
      ['foo', 'bar'],
      ['foo', 'baz'],
      ['bar', 'baz'],
      ['bar', 'foo'],
      ['baz', 'bar'],
    ];

    const expected = {
      foo: {
        bar: 0.75,
        baz: 0.25,
      },
      bar: {
        foo: 0.5,
        baz: 0.5,
      },
      baz: {
        bar: 1,
      },
    };

    expect(probablize(countByFrom(input))).toEqual(expected);
  });
});