# Copyright 2016 The TensorFlow Authors. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may not
# use this file except in compliance with the License.  You may obtain a copy of
# the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  See the
# License for the specific language governing permissions and limitations under
# the License.
# ==============================================================================

"""Tests for clustering_ops."""

from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

import numpy as np
# pylint: disable=unused-import
import tensorflow as tf
# pylint: enable=unused-import


class KmeansPlusPlusInitializationTest(tf.test.TestCase):

  # All but one input point are close to (101, 1). With uniform random sampling,
  # it is highly improbable for (-1, -1) to be selected.
  def setUp(self):
    self._points = np.array([
        [100., 0.],
        [101., 2.],
        [102., 0.],
        [100., 1.],
        [100., 2.],
        [101., 0.],
        [101., 0.],
        [101., 1.],
        [102., 0.],
        [-1., -1.]
    ]).astype(np.float32)

  def runTestWithSeed(self, seed):
    with self.test_session():
      sampled_points = tf.contrib.factorization.kmeans_plus_plus_initialization(
          self._points, 3, seed, (seed % 5) - 1)
      self.assertAllClose(sorted(sampled_points.eval().tolist()), [
          [-1., -1.],
          [101., 1.],
          [101., 1.]
      ], atol=1.0)

  def testBasic(self):
    for seed in range(100):
      self.runTestWithSeed(seed)


# A simple test that can be verified by hand.
class NearestCentersTest(tf.test.TestCase):

  def setUp(self):
    self._points = np.array([
        [100., 0.],
        [101., 2.],
        [99., 2.],
        [1., 1.]
    ]).astype(np.float32)

    self._centers = np.array([
        [100., 0.],
        [99., 1.],
        [50., 50.],
        [0., 0.],
        [1., 1.]
    ]).astype(np.float32)

  def testNearest1(self):
    with self.test_session():
      [indices, distances] = tf.contrib.factorization.nearest_neighbors(
          self._points, self._centers, 1)
      self.assertAllClose(indices.eval(), [[0], [0], [1], [4]])
      self.assertAllClose(distances.eval(), [[0.], [5.], [1.], [0.]])

  def testNearest2(self):
    with self.test_session():
      [indices, distances] = tf.contrib.factorization.nearest_neighbors(
          self._points, self._centers, 2)
      self.assertAllClose(indices.eval(),
                          [[0, 1], [0, 1], [1, 0], [4, 3]])
      self.assertAllClose(distances.eval(),
                          [[0., 2.], [5., 5.], [1., 5.], [0., 2.]])


# A test with large inputs.
class NearestCentersLargeTest(tf.test.TestCase):

  def setUp(self):
    num_points = 1000
    num_centers = 2000
    num_dim = 100
    max_k = 5
    # Construct a small number of random points and later tile them.
    points_per_tile = 10
    assert num_points % points_per_tile == 0
    points = np.random.standard_normal([points_per_tile, num_dim]).astype(
        np.float32)
    # Construct random centers.
    self._centers = np.random.standard_normal([num_centers, num_dim]).astype(
        np.float32)
    # Exhaustively compute expected nearest neighbors.
    def squared_distance(x, y):
      return np.linalg.norm(x - y, ord=2) ** 2
    nearest_neighbors = [sorted([(squared_distance(point, self._centers[j]), j)
                                 for j in range(num_centers)])[:max_k]
                         for point in points]
    expected_nearest_neighbor_indices = np.array(
        [[i for _, i in nn] for nn in nearest_neighbors])
    expected_nearest_neighbor_squared_distances = np.array(
        [[dist for dist, _ in nn] for nn in nearest_neighbors])
    # Tile points and expected results to reach requested size (num_points)
    (self._points,
     self._expected_nearest_neighbor_indices,
     self._expected_nearest_neighbor_squared_distances) = (
         np.tile(x, (num_points / points_per_tile, 1))
         for x in (points,
                   expected_nearest_neighbor_indices,
                   expected_nearest_neighbor_squared_distances))

  def testNearest1(self):
    with self.test_session():
      [indices, distances] = tf.contrib.factorization.nearest_neighbors(
          self._points, self._centers, 1)
      self.assertAllClose(indices.eval(),
                          self._expected_nearest_neighbor_indices[:, [0]])
      self.assertAllClose(
          distances.eval(),
          self._expected_nearest_neighbor_squared_distances[:, [0]])

  def testNearest5(self):
    with self.test_session():
      [indices, distances] = tf.contrib.factorization.nearest_neighbors(
          self._points, self._centers, 5)
      self.assertAllClose(indices.eval(),
                          self._expected_nearest_neighbor_indices[:, 0:5])
      self.assertAllClose(
          distances.eval(),
          self._expected_nearest_neighbor_squared_distances[:, 0:5])


if __name__ == '__main__':
  np.random.seed(0)
  tf.test.main()
