Python nn.moments函数代码示例

def batch_normalize(tensor_in, epsilon=1e-5, convnet=False, decay=0.9, scale_after_normalization=True):
    """Batch Normalization

  Args:
    tensor_in: input Tensor, 4D shape: [batch, in_height, in_width, in_depth].
    epsilon : A float number to avoid being divided by 0.
    decay: decay rate for exponential moving average.
    convnet: Whether this is for convolutional net use. If this is True,
      moments will sum across axis [0, 1, 2]. Otherwise, only [0].
    scale_after_normalization: Whether to scale after normalization.
  """
    shape = tensor_in.get_shape().as_list()

    with vs.variable_scope("batch_norm"):
        gamma = vs.get_variable("gamma", [shape[-1]], initializer=init_ops.random_normal_initializer(1.0, 0.02))
        beta = vs.get_variable("beta", [shape[-1]], initializer=init_ops.constant_initializer(0.0))
        ema = moving_averages.ExponentialMovingAverage(decay=decay)
        if convnet:
            assign_mean, assign_var = nn.moments(tensor_in, [0, 1, 2])
        else:
            assign_mean, assign_var = nn.moments(tensor_in, [0])
        ema_assign_op = ema.apply([assign_mean, assign_var])
        ema_mean, ema_var = ema.average(assign_mean), ema.average(assign_var)

        def update_mean_var():
            """Internal function that updates mean and variance during training"""
            with ops.control_dependencies([ema_assign_op]):
                return array_ops_.identity(assign_mean), array_ops_.identity(assign_var)

        is_training = array_ops_.squeeze(ops.get_collection("IS_TRAINING"))
        mean, variance = control_flow_ops.cond(is_training, update_mean_var, lambda: (ema_mean, ema_var))
        return nn.batch_norm_with_global_normalization(
            tensor_in, mean, variance, beta, gamma, epsilon, scale_after_normalization=scale_after_normalization
        )

  def _inverse_log_det_jacobian(self, y, use_saved_statistics=False):
    if not y.shape.is_fully_defined():
      raise ValueError("Input must have shape known at graph construction.")
    input_shape = np.int32(y.shape.as_list())

    if not self.batchnorm.built:
      # Create variables.
      self.batchnorm.build(input_shape)

    event_dims = self.batchnorm.axis
    reduction_axes = [i for i in range(len(input_shape)) if i not in event_dims]

    if use_saved_statistics or not self._training:
      log_variance = math_ops.log(
          self.batchnorm.moving_variance + self.batchnorm.epsilon)
    else:
      # At training-time, ildj is computed from the mean and log-variance across
      # the current minibatch.
      _, v = nn.moments(y, axes=reduction_axes, keepdims=True)
      log_variance = math_ops.log(v + self.batchnorm.epsilon)

    # `gamma` and `log Var(y)` reductions over event_dims.
    # Log(total change in area from gamma term).
    log_total_gamma = math_ops.reduce_sum(math_ops.log(self.batchnorm.gamma))

    # Log(total change in area from log-variance term).
    log_total_variance = math_ops.reduce_sum(log_variance)
    # The ildj is scalar, as it does not depend on the values of x and are
    # constant across minibatch elements.
    return log_total_gamma - 0.5 * log_total_variance

  def test_virtual_statistics(self):
    """Check that `_virtual_statistics` gives same result as `nn.moments`."""
    random_seed.set_random_seed(1234)

    batch_axis = 0
    partial_batch = random_ops.random_normal([4, 5, 7, 3])
    single_example = random_ops.random_normal([1, 5, 7, 3])
    full_batch = array_ops.concat([partial_batch, single_example], axis=0)

    for reduction_axis in range(1, 4):
      # Get `nn.moments` on the full batch.
      reduction_axes = list(range(4))
      del reduction_axes[reduction_axis]
      mom_mean, mom_variance = nn.moments(full_batch, reduction_axes)

      # Get virtual batch statistics.
      vb_reduction_axes = list(range(4))
      del vb_reduction_axes[reduction_axis]
      del vb_reduction_axes[batch_axis]
      vbn = virtual_batchnorm.VBN(partial_batch, reduction_axis)
      vb_mean, mean_sq = vbn._virtual_statistics(
          single_example, vb_reduction_axes)
      vb_variance = mean_sq - math_ops.square(vb_mean)
      # Remove singleton batch dim for easy comparisons.
      vb_mean = array_ops.squeeze(vb_mean, batch_axis)
      vb_variance = array_ops.squeeze(vb_variance, batch_axis)

      with self.cached_session(use_gpu=True) as sess:
        vb_mean_np, vb_var_np, mom_mean_np, mom_var_np = sess.run([
            vb_mean, vb_variance, mom_mean, mom_variance])

      self.assertAllClose(mom_mean_np, vb_mean_np)
      self.assertAllClose(mom_var_np, vb_var_np)

  def call(self, inputs):
    # Compute the axes along which to reduce the mean / variance
    input_shape = inputs.shape
    ndims = len(input_shape)

    # Calculate the moments on the last axis (layer activations).
    mean, variance = nn.moments(inputs, self.axis, keep_dims=True)

    # Broadcasting only necessary for norm where the axis is not just
    # the last dimension
    broadcast_shape = [1] * ndims
    for dim in self.axis:
      broadcast_shape[dim] = input_shape.dims[dim].value
    def _broadcast(v):
      if (v is not None and len(v.shape) != ndims and
          self.axis != [ndims - 1]):
        return array_ops.reshape(v, broadcast_shape)
      return v
    scale, offset = _broadcast(self.gamma), _broadcast(self.beta)

    # Compute layer normalization using the batch_normalization function.
    outputs = nn.batch_normalization(
        inputs,
        mean,
        variance,
        offset=offset,
        scale=scale,
        variance_epsilon=self.epsilon)

    # If some components of the shape got lost due to adjustments, fix that.
    outputs.set_shape(input_shape)

    return outputs

 def _update_mean_var():
   """Internal function that updates mean and variance during training."""
   axis = [0, 1, 2] if convnet else [0]
   mean, var = nn.moments(tensor_in, axis)
   update_moving_mean = moving_averages.assign_moving_average(
       moving_mean, mean, decay)
   update_moving_var = moving_averages.assign_moving_average(
       moving_var, var, decay)
   with ops.control_dependencies([update_moving_mean, update_moving_var]):
     return array_ops_.identity(mean), array_ops_.identity(var)

def _normalize_patches(patches):
  """Normalize patches by their mean and standard deviation.

  Args:
      patches: (tensor) The batch of patches (batch, size, size, channels).
  Returns:
      Tensor (batch, size, size, channels) of the normalized patches.
  """
  patches = array_ops.concat(patches, 0)
  mean, variance = nn.moments(patches, [1, 2, 3], keep_dims=True)
  patches = (patches - mean) / math_ops.sqrt(variance)
  return array_ops.reshape(patches, [array_ops.shape(patches)[0], -1])

 def series_start_updates():
   # If this is the lowest-time chunk that we have seen so far, update
   # series start moments to reflect that. Note that these statistics are
   # "best effort", as there are race conditions in the update (however,
   # they should eventually converge if the start of the series is
   # presented enough times).
   mean, variance = nn.moments(
       values[min_time_batch, :self._starting_variance_window_size],
       axes=[0])
   return control_flow_ops.group(
       state_ops.assign(statistics.series_start_moments.mean, mean),
       state_ops.assign(statistics.series_start_moments.variance,
                        variance))

def batch_norm(x, deterministic, alpha=0.9, shift=True, scope='bn'):
    with vs.variable_scope(scope):
        dtype = x.dtype
        input_shape = x.get_shape().as_list()
        feat_dim = input_shape[-1]
        axes = range(len(input_shape)-1)
        
        if shift:
            beta = vs.get_variable(
                    scope+"_beta", shape=[feat_dim],
                    initializer=init_ops.zeros_initializer, dtype=dtype)
        else:
            beta = vs.get_variable(
                scope+"_beta", shape=[feat_dim],
                initializer=init_ops.zeros_initializer, 
                dtype=dtype, trainable=False)
        
        gamma = vs.get_variable(
                    scope+"_gamma", shape=[feat_dim],
                    initializer=init_ops.constant_initializer(0.1), dtype=dtype)
        
        mean = vs.get_variable(scope+"_mean", shape=[feat_dim],
                                       initializer=init_ops.zeros_initializer,
                                       dtype=dtype, trainable=False)
        
        var = vs.get_variable(scope+"_var", shape=[feat_dim],
                                          initializer=init_ops.ones_initializer,
                                          dtype=dtype, trainable=False)
        
        counter = vs.get_variable(scope+"_counter", shape=[],
                                          initializer=init_ops.constant_initializer(0),
                                          dtype=tf.int64, trainable=False)
        
        zero_cnt = vs.get_variable(scope+"_zero_cnt", shape=[],
                                          initializer=init_ops.constant_initializer(0),
                                          dtype=tf.int64, trainable=False)
        
        batch_mean, batch_var = moments(x, axes, name=scope+'_moments')
        
        mean, var = cond(math_ops.equal(counter, zero_cnt), lambda: (batch_mean, batch_var), 
                         lambda: (mean, var))
        
         
        mean, var, counter = cond(deterministic, lambda: (mean, var, counter), 
                                 lambda: ((1-alpha) * batch_mean + alpha * mean, 
                                         (1-alpha) * batch_var + alpha * var, 
                                         counter + 1))
        normed = batch_normalization(x, mean, var, beta, gamma, 1e-8)
    return normed

  def test_statistics(self):
    """Check that `_statistics` gives the same result as `nn.moments`."""
    random_seed.set_random_seed(1234)

    tensors = random_ops.random_normal([4, 5, 7, 3])
    for axes in [(3), (0, 2), (1, 2, 3)]:
      vb_mean, mean_sq = virtual_batchnorm._statistics(tensors, axes)
      mom_mean, mom_var = nn.moments(tensors, axes)
      vb_var = mean_sq - math_ops.square(vb_mean)

      with self.cached_session(use_gpu=True) as sess:
        vb_mean_np, vb_var_np, mom_mean_np, mom_var_np = sess.run([
            vb_mean, vb_var, mom_mean, mom_var])

      self.assertAllClose(mom_mean_np, vb_mean_np)
      self.assertAllClose(mom_var_np, vb_var_np)

  def _testGlobalGradient(self, from_y="mean"):
    with self.test_session():
      x_shape = [3, 5, 4, 2]
      x_val = np.random.random_sample(x_shape).astype(np.float64)
      x = constant_op.constant(x_val)
      x.set_shape(x_shape)

      axes = [0, 1, 2]
      y_shape = [2]  # Depth of x
      out_mean, out_var = nn.moments(x, axes)
      if from_y == "mean":
        y = out_mean
      elif from_y == "var":
        y = out_var
      err = gc.ComputeGradientError(x, x_shape, y, y_shape)
      print "Moments %s gradient err = %g" % (from_y, err)
      self.assertLess(err, 1e-11)

    def RunMomentTest(self, shape, global_norm):
        with self.test_session():
            # shape = [batch, width, height, depth]
            assert len(shape) == 4

            x_numpy = np.random.normal(size=shape).astype(np.float32)
            x = constant_op.constant(x_numpy)

            axes = [0, 1, 2] if global_norm else [0]
            mean, var = nn.moments(x, axes)

            num_elements = np.prod([shape[i] for i in axes])

            ax = (0, 1, 2) if global_norm else (0)
            expected_mean = np.sum(x_numpy, axis=ax) / num_elements
            expected_mean_squared = np.multiply(expected_mean, expected_mean)
            expected_x_squared = np.sum(np.multiply(x_numpy, x_numpy), axis=ax) / num_elements
            expected_variance = expected_x_squared - expected_mean_squared

            # Check that the moments are correct.
            self.assertAllClose(expected_mean, mean.eval())
            self.assertAllClose(expected_variance, var.eval())

  def call(self, inputs, training=False):
    # First, compute the axes along which to reduce the mean / variance,
    # as well as the broadcast shape to be used for all parameters.
    input_shape = inputs.get_shape()
    ndim = len(input_shape)
    reduction_axes = list(range(len(input_shape)))
    del reduction_axes[self.axis]
    broadcast_shape = [1] * len(input_shape)
    broadcast_shape[self.axis] = input_shape[self.axis].value

    # Determines whether broadcasting is needed.
    needs_broadcasting = (sorted(reduction_axes) != range(ndim)[:-1])

    # Determine boolean training boolean value. May be False, True, None.
    # If None, it is assumed that `training` is a variable to be used in `cond`.
    if isinstance(training, bool):
      training_bool = training
    else:
      try:
        training_bool = tensor_util.constant_value(training)
      except TypeError:
        training_bool = None

    # Obtain current current batch mean, variance, if necessary.
    if training_bool is not False:
      # Use a copy of moving_mean as a shift to compute more reliable moments.
      shift = math_ops.add(self.moving_mean, 0)
      if needs_broadcasting:
        shift = array_ops.reshape(shift, broadcast_shape)
        broadcast_mean, broadcast_variance = nn.moments(
            inputs, reduction_axes, shift=shift, keep_dims=True)
        mean = array_ops.reshape(broadcast_mean, [-1])
        variance = array_ops.reshape(broadcast_variance, [-1])
      else:
        mean, variance = nn.moments(inputs, reduction_axes, shift=shift)

    # Prepare updates if necessary.
    if training_bool is not False and not self.updates:
      mean_update = moving_averages.assign_moving_average(
          self.moving_mean, mean, self.momentum, zero_debias=False)
      variance_update = moving_averages.assign_moving_average(
          self.moving_variance, variance, self.momentum, zero_debias=False)
      # In the future this should be refactored into a self.add_update
      # methods in order to allow for instance-based BN layer sharing
      # across unrelated input streams (e.g. like in Keras).
      self.updates.append(mean_update)
      self.updates.append(variance_update)

    # Normalize batch.
    if needs_broadcasting:
      # In this case we must explictly broadcast all parameters.
      broadcast_moving_mean = array_ops.reshape(self.moving_mean,
                                                broadcast_shape)
      broadcast_moving_variance = array_ops.reshape(self.moving_variance,
                                                    broadcast_shape)
      if self.center:
        broadcast_beta = array_ops.reshape(self.beta, broadcast_shape)
      else:
        broadcast_beta = None
      if self.scale:
        broadcast_gamma = array_ops.reshape(self.gamma, broadcast_shape)
      else:
        broadcast_gamma = None

      if training_bool is not False:
        normed_inputs_training = nn.batch_normalization(inputs,
                                                        broadcast_mean,
                                                        broadcast_variance,
                                                        broadcast_beta,
                                                        broadcast_gamma,
                                                        self.epsilon)
      normed_inputs = nn.batch_normalization(inputs,
                                             broadcast_moving_mean,
                                             broadcast_moving_variance,
                                             broadcast_beta,
                                             broadcast_gamma,
                                             self.epsilon)
    else:
      # No need for broadcasting.
      if training_bool is not False:
        normed_inputs_training = nn.batch_normalization(
            inputs,
            mean,
            variance,
            self.beta if self.center else None,
            self.gamma if self.scale else None,
            self.epsilon)
      normed_inputs = nn.batch_normalization(inputs,
                                             self.moving_mean,
                                             self.moving_variance,
                                             self.beta if self.center else None,
                                             self.gamma if self.scale else None,
                                             self.epsilon)

    # Return the proper output depending on the boolean training phase.
    if training_bool is True:
      return normed_inputs_training
    if training_bool is False:
      return normed_inputs
    return control_flow_ops.cond(training,
#.........这里部分代码省略.........

  def call(self, inputs, training=False):
    if self.fused:
      return self._fused_batch_norm(inputs, training=training)

    # First, compute the axes along which to reduce the mean / variance,
    # as well as the broadcast shape to be used for all parameters.
    input_shape = inputs.get_shape()
    ndim = len(input_shape)
    reduction_axes = list(range(len(input_shape)))
    del reduction_axes[self.axis]
    broadcast_shape = [1] * len(input_shape)
    broadcast_shape[self.axis] = input_shape[self.axis].value

    # Determines whether broadcasting is needed.
    needs_broadcasting = (sorted(reduction_axes) != list(range(ndim))[:-1])

    scale, offset = self.gamma, self.beta

    # Determine a boolean value for `training`: could be True, False, or None.
    training_value = utils.constant_value(training)
    if training_value is not False:
      # Some of the computations here are not necessary when training==False
      # but not a constant. However, this makes the code simpler.
      mean, variance = nn.moments(inputs, reduction_axes)
      mean = _smart_select(training,
                           lambda: mean,
                           lambda: self.moving_mean)
      variance = _smart_select(training,
                               lambda: variance,
                               lambda: self.moving_variance)

      if self.renorm:
        r, d, new_mean, new_variance = self._renorm_correction_and_moments(
            mean, variance, training)
        # When training, the normalized values (say, x) will be transformed as
        # x * gamma + beta without renorm, and (x * r + d) * gamma + beta
        # = x * (r * gamma) + (d * gamma + beta) with renorm.
        scale = array_ops.stop_gradient(r, name='renorm_r')
        offset = array_ops.stop_gradient(d, name='renorm_d')
        if self.gamma is not None:
          scale *= self.gamma
          offset *= self.gamma
        if self.beta is not None:
          offset += self.beta
      else:
        new_mean, new_variance = mean, variance

      # Update moving averages when training, and prevent updates otherwise.
      decay = _smart_select(training, lambda: self.momentum, lambda: 1.)
      mean_update = moving_averages.assign_moving_average(
          self.moving_mean, new_mean, decay, zero_debias=False)
      variance_update = moving_averages.assign_moving_average(
          self.moving_variance, new_variance, decay, zero_debias=False)

      self.add_update(mean_update, inputs=inputs)
      self.add_update(variance_update, inputs=inputs)

    else:
      mean, variance = self.moving_mean, self.moving_variance

    def _broadcast(v):
      if needs_broadcasting and v is not None:
        # In this case we must explicitly broadcast all parameters.
        return array_ops.reshape(v, broadcast_shape)
      return v

    return nn.batch_normalization(inputs,
                                  _broadcast(mean),
                                  _broadcast(variance),
                                  _broadcast(offset),
                                  _broadcast(scale),
                                  self.epsilon)

def batch_norm(inputs,
               decay=0.999,
               center=True,
               scale=False,
               epsilon=0.001,
               activation_fn=None,
               updates_collections=ops.GraphKeys.UPDATE_OPS,
               is_training=True,
               reuse=None,
               variables_collections=None,
               outputs_collections=None,
               trainable=True,
               scope=None):
  """Adds a Batch Normalization layer from http://arxiv.org/abs/1502.03167.
    "Batch Normalization: Accelerating Deep Network Training by Reducing
    Internal Covariate Shift"
    Sergey Ioffe, Christian Szegedy
  Can be used as a normalizer function for conv2d and fully_connected.
  Args:
    -inputs: a tensor of size `[batch_size, height, width, channels]`
            or `[batch_size, channels]`.
    -decay: decay for the moving average.
    -center: If True, subtract `beta`. If False, `beta` is ignored.
    -scale: If True, multiply by `gamma`. If False, `gamma` is
      not used. When the next layer is linear (also e.g. `nn.relu`), this can be
      disabled since the scaling can be done by the next layer.
    -epsilon: small float added to variance to avoid dividing by zero.
    -activation_fn: Optional activation function.
    -updates_collections: collections to collect the update ops for computation.
      If None, a control dependency would be added to make sure the updates are
      computed.
    -is_training: whether or not the layer is in training mode. In training mode
      it would accumulate the statistics of the moments into `moving_mean` and
      `moving_variance` using an exponential moving average with the given
      `decay`. When it is not in training mode then it would use the values of
      the `moving_mean` and the `moving_variance`.
    -reuse: whether or not the layer and its variables should be reused. To be
      able to reuse the layer scope must be given.
    -variables_collections: optional collections for the variables.
    -outputs_collections: collections to add the outputs.
    -trainable: If `True` also add variables to the graph collection
      `GraphKeys.TRAINABLE_VARIABLES` (see tf.Variable).
    -scope: Optional scope for `variable_op_scope`.
  Returns:
    a tensor representing the output of the operation.
  """
  with variable_scope.variable_op_scope([inputs],scope, 'BatchNorm', reuse=reuse) as sc:
    inputs_shape = inputs.get_shape()
    dtype = inputs.dtype.base_dtype
    axis = list(range(len(inputs_shape) - 1))
    params_shape = inputs_shape[-1:]
    # Allocate parameters for the beta and gamma of the normalization.
    beta, gamma = None, None
    if center:
      beta_collections = utils.get_variable_collections(variables_collections,'beta')
      beta = variables.model_variable('beta',shape=params_shape,dtype=dtype,initializer=init_ops.zeros_initializer,collections=beta_collections,trainable=trainable)
    if scale:
      gamma_collections = utils.get_variable_collections(variables_collections,'gamma')
      gamma = variables.model_variable('gamma',shape=params_shape,dtype=dtype,initializer=init_ops.ones_initializer,collections=gamma_collections,trainable=trainable)
    # Create moving_mean and moving_variance variables and add them to the
    # appropiate collections.
    moving_mean_collections = utils.get_variable_collections(variables_collections, 'moving_mean')
    moving_mean = variables.model_variable('moving_mean',shape=params_shape,dtype=dtype,initializer=init_ops.zeros_initializer,trainable=False,collections=moving_mean_collections)
    moving_variance_collections = utils.get_variable_collections(variables_collections, 'moving_variance')
    moving_variance = variables.model_variable('moving_variance',shape=params_shape,dtype=dtype,initializer=init_ops.ones_initializer,trainable=False,collections=moving_variance_collections)
    if is_training:
      # Calculate the moments based on the individual batch.
      mean, variance = nn.moments(inputs, axis, shift=moving_mean)
      # Update the moving_mean and moving_variance moments.
      update_moving_mean = moving_averages.assign_moving_average(moving_mean, mean, decay)
      update_moving_variance = moving_averages.assign_moving_average(moving_variance, variance, decay)
      if updates_collections is None:
        # Make sure the updates are computed here.
        with ops.control_dependencies([update_moving_mean,update_moving_variance]):
          outputs = nn.batch_normalization(inputs, mean, variance, beta, gamma, epsilon)
      else:
        # Collect the updates to be computed later.
        ops.add_to_collections(updates_collections, update_moving_mean)
        ops.add_to_collections(updates_collections, update_moving_variance)
        outputs = nn.batch_normalization(inputs, mean, variance, beta, gamma, epsilon)
    else:
      outputs = nn.batch_normalization(
          inputs, moving_mean, moving_variance, beta, gamma, epsilon)
    outputs.set_shape(inputs.get_shape())
    if activation_fn:
      outputs = activation_fn(outputs)
    return utils.collect_named_outputs(outputs_collections, sc.name, outputs)

 def _moments(self, inputs, reduction_axes, keep_dims):
   return nn.moments(inputs, reduction_axes, keep_dims=keep_dims)