# Copyright (c) 2015-present, Facebook, Inc.
# All rights reserved.
#
# This source code is licensed under the CC-by-NC license found in the
# LICENSE file in the root directory of this source tree.

#! /usr/bin/env python2

import libfb.py.mkl  # noqa

import numpy as np
from libfb import testutil

import faiss


class TestClustering(testutil.BaseFacebookTestCase):

    def test_clustering(self):
        d = 64
        n = 1000
        np.random.seed(123)
        x = np.random.random(size=(n, d)).astype('float32')

        km = faiss.Kmeans(d, 32, niter=10)
        err32 = km.train(x)

        # check that objective is decreasing
        prev = 1e50
        for o in km.obj:
            self.assertGreater(prev, o)
            prev = o

        km = faiss.Kmeans(d, 64, niter=10)
        err64 = km.train(x)

        # check that 64 centroids give a lower quantization error than 32
        self.assertGreater(err32, err64)


class TestPCA(testutil.BaseFacebookTestCase):

    def test_pca(self):
        d = 64
        n = 1000
        np.random.seed(123)
        x = np.random.random(size=(n, d)).astype('float32')

        pca = faiss.PCAMatrix(d, 10)
        pca.train(x)
        y = pca.apply_py(x)

        # check that energy per component is decreasing
        column_norm2 = (y**2).sum(0)

        prev = 1e50
        for o in column_norm2:
            self.assertGreater(prev, o)
            prev = o


class TestProductQuantizer(testutil.BaseFacebookTestCase):

    def test_pq(self):
        d = 64
        n = 1000
        cs = 4
        np.random.seed(123)
        x = np.random.random(size=(n, d)).astype('float32')
        pq = faiss.ProductQuantizer(d, cs, 8)
        pq.train(x)
        codes = pq.compute_codes(x)
        x2 = pq.decode(codes)
        diff = ((x - x2)**2).sum()

        # print "diff=", diff
        # diff= 1807.98
        self.assertGreater(2500, diff)