Python utils.gaussian_kernel_matrix方法代碼示例

# 需要導入模塊: import utils [as 別名]
# 或者: from utils import gaussian_kernel_matrix [as 別名]
def maximum_mean_discrepancy(x, y, kernel=utils.gaussian_kernel_matrix):
  r"""Computes the Maximum Mean Discrepancy (MMD) of two samples: x and y.

  Maximum Mean Discrepancy (MMD) is a distance-measure between the samples of
  the distributions of x and y. Here we use the kernel two sample estimate
  using the empirical mean of the two distributions.

  MMD^2(P, Q) = || \E{\phi(x)} - \E{\phi(y)} ||^2
              = \E{ K(x, x) } + \E{ K(y, y) } - 2 \E{ K(x, y) },

  where K = <\phi(x), \phi(y)>,
    is the desired kernel function, in this case a radial basis kernel.

  Args:
      x: a tensor of shape [num_samples, num_features]
      y: a tensor of shape [num_samples, num_features]
      kernel: a function which computes the kernel in MMD. Defaults to the
              GaussianKernelMatrix.

  Returns:
      a scalar denoting the squared maximum mean discrepancy loss.
  """
  with tf.name_scope('MaximumMeanDiscrepancy'):
    # \E{ K(x, x) } + \E{ K(y, y) } - 2 \E{ K(x, y) }
    cost = tf.reduce_mean(kernel(x, x))
    cost += tf.reduce_mean(kernel(y, y))
    cost -= 2 * tf.reduce_mean(kernel(x, y))

    # We do not allow the loss to become negative.
    cost = tf.where(cost > 0, cost, 0, name='value')
  return cost 

# 需要導入模塊: import utils [as 別名]
# 或者: from utils import gaussian_kernel_matrix [as 別名]
def mmd_loss(source_samples, target_samples, weight, scope=None):
  """Adds a similarity loss term, the MMD between two representations.

  This Maximum Mean Discrepancy (MMD) loss is calculated with a number of
  different Gaussian kernels.

  Args:
    source_samples: a tensor of shape [num_samples, num_features].
    target_samples: a tensor of shape [num_samples, num_features].
    weight: the weight of the MMD loss.
    scope: optional name scope for summary tags.

  Returns:
    a scalar tensor representing the MMD loss value.
  """
  sigmas = [
      1e-6, 1e-5, 1e-4, 1e-3, 1e-2, 1e-1, 1, 5, 10, 15, 20, 25, 30, 35, 100,
      1e3, 1e4, 1e5, 1e6
  ]
  gaussian_kernel = partial(
      utils.gaussian_kernel_matrix, sigmas=tf.constant(sigmas))

  loss_value = maximum_mean_discrepancy(
      source_samples, target_samples, kernel=gaussian_kernel)
  loss_value = tf.maximum(1e-4, loss_value) * weight
  assert_op = tf.Assert(tf.is_finite(loss_value), [loss_value])
  with tf.control_dependencies([assert_op]):
    tag = 'MMD Loss'
    if scope:
      tag = scope + tag
    tf.summary.scalar(tag, loss_value)
    tf.losses.add_loss(loss_value)

  return loss_value 

# 需要導入模塊: import utils [as 別名]
# 或者: from utils import gaussian_kernel_matrix [as 別名]
def test_mmd_name(self):
    with self.test_session():
      x = tf.random_uniform((2, 3), seed=1)
      kernel = partial(utils.gaussian_kernel_matrix, sigmas=tf.constant([1.]))
      loss = losses.maximum_mean_discrepancy(x, x, kernel)

      self.assertEquals(loss.op.name, 'MaximumMeanDiscrepancy/value') 

# 需要導入模塊: import utils [as 別名]
# 或者: from utils import gaussian_kernel_matrix [as 別名]
def test_mmd_is_zero_when_inputs_are_same(self):
    with self.test_session():
      x = tf.random_uniform((2, 3), seed=1)
      kernel = partial(utils.gaussian_kernel_matrix, sigmas=tf.constant([1.]))
      self.assertEquals(0, losses.maximum_mean_discrepancy(x, x, kernel).eval()) 

# 需要導入模塊: import utils [as 別名]
# 或者: from utils import gaussian_kernel_matrix [as 別名]
def test_fast_mmd_is_similar_to_slow_mmd(self):
    with self.test_session():
      x = tf.constant(np.random.normal(size=(2, 3)), tf.float32)
      y = tf.constant(np.random.rand(2, 3), tf.float32)

      cost_old = MaximumMeanDiscrepancySlow(x, y, [1.]).eval()
      kernel = partial(utils.gaussian_kernel_matrix, sigmas=tf.constant([1.]))
      cost_new = losses.maximum_mean_discrepancy(x, y, kernel).eval()

      self.assertAlmostEqual(cost_old, cost_new, delta=1e-5) 

# 需要導入模塊: import utils [as 別名]
# 或者: from utils import gaussian_kernel_matrix [as 別名]
def test_mmd_is_zero_when_distributions_are_same(self):

    with self.test_session():
      x = tf.random_uniform((1000, 10), seed=1)
      y = tf.random_uniform((1000, 10), seed=3)

      kernel = partial(utils.gaussian_kernel_matrix, sigmas=tf.constant([100.]))
      loss = losses.maximum_mean_discrepancy(x, y, kernel=kernel).eval()

      self.assertAlmostEqual(0, loss, delta=1e-4) 

# 需要導入模塊: import utils [as 別名]
# 或者: from utils import gaussian_kernel_matrix [as 別名]
def __init__(self, encoder, configs):
        super(MMD, self).__init__()
        self.sigmas = torch.FloatTensor([
            1e-6, 1e-5, 1e-4, 1e-3, 1e-2, 1e-1,
            1, 5, 10, 15, 20, 25, 30, 35, 100,
            1e3, 1e4, 1e5, 1e6
        ])
        if configs.cuda:
            self.sigmas = self.sigmas.cuda()
        self.gaussian_kernel = partial(utils.gaussian_kernel_matrix, sigmas=self.sigmas)