Add common.get_random_ndcg (cont.)

from math import log2

import unittest

from arqmath_eval import get_random_ndcg

class TestGetRandomNDCG(unittest.TestCase):

    def test(self):

        ndcg = get_random_ndcg('task1', 'test')

        expected_judgement = (

            4 * 3.0 +

            4 * 2.0 +

            8 * 1.0 +

            2 * 0.0

        ) / 18

        expected_dcg = 0.0

        for i in range(1, 19):

            expected_dcg += expected_judgement / log2(i + 1)

        expected_idcg = 0.0

        for i in range(1, 5):

            expected_idcg += 3.0 / log2(i + 1)

        for i in range(5, 9):

            expected_idcg += 2.0 / log2(i + 1)

        for i in range(9, 17):

            expected_idcg += 1.0 / log2(i + 1)

        for i in range(17, 19):

            expected_idcg += 0.0 / log2(i + 1)

        expected_ndcg = expected_dcg / expected_idcg

        self.assertEqual(expected_ndcg, ndcg)