Python math_ops.div函数代码示例

def _safe_div(numerator, denominator, name="value"):
  """Computes a safe divide which returns 0 if the denominator is zero.

  Note that the function contains an additional conditional check that is
  necessary for avoiding situations where the loss is zero causing NaNs to
  creep into the gradient computation.

  Args:
    numerator: An arbitrary `Tensor`.
    denominator: `Tensor` whose shape matches `numerator` and whose values are
      assumed to be non-negative.
    name: An optional name for the returned op.

  Returns:
    The element-wise value of the numerator divided by the denominator.
  """
  if isinstance(denominator, float):
    if math_ops.equal(denominator, 0.0):
      return ops.convert_to_tensor(0.0, dtype=numerator.dtype)
    return math_ops.div(numerator, denominator)
  if context.in_eager_mode() and denominator._rank() == 0:  # pylint: disable=protected-access
    if math_ops.equal(denominator, 0.0):
      return ops.convert_to_tensor(0.0, dtype=numerator.dtype)
    return math_ops.div(numerator, denominator)
  return array_ops.where(
      math_ops.greater(denominator, 0),
      math_ops.div(numerator, array_ops.where(
          math_ops.equal(denominator, 0),
          array_ops.ones_like(denominator), denominator)),
      array_ops.zeros_like(numerator),
      name=name)

 def testAssertDivideByZero(self):
   with self.test_session() as sess:
     epsilon = ops.convert_to_tensor(1e-20)
     x = ops.convert_to_tensor(0.0)
     y = ops.convert_to_tensor(1.0)
     z = ops.convert_to_tensor(2.0)
     # assert(epsilon < y)
     # z / y
     with sess.graph.control_dependencies([
         control_flow_ops.Assert(
             math_ops.less(epsilon, y), ["Divide-by-zero"])
     ]):
       out = math_ops.div(z, y)
     self.assertAllEqual(2.0, out.eval())
     # assert(epsilon < x)
     # z / x
     #
     # This tests printing out multiple tensors
     with sess.graph.control_dependencies([
         control_flow_ops.Assert(
             math_ops.less(epsilon, x), ["Divide-by-zero", "less than x"])
     ]):
       out = math_ops.div(z, x)
     with self.assertRaisesOpError("less than x"):
       out.eval()

 def compute_best_f1_score(tp, fp, fn, name):
   precision_at_t = math_ops.div(tp, epsilon + tp + fp,
                                 name='precision_' + name)
   recall_at_t = math_ops.div(tp, epsilon + tp + fn, name='recall_' + name)
   # Compute F1 score.
   f1_at_thresholds = (
       2.0 * precision_at_t * recall_at_t /
       (precision_at_t + recall_at_t + epsilon))
   return math_ops.reduce_max(f1_at_thresholds)

  def inference_graph(self, input_data, **inference_args):
    """Constructs a TF graph for evaluating a random forest.

    Args:
      input_data: A tensor or dict of string->Tensor for the input data.
                  This input_data must generate the same spec as the
                  input_data used in training_graph:  the dict must have
                  the same keys, for example, and all tensors must have
                  the same size in their first dimension.
      **inference_args: Keyword arguments to pass through to each tree.

    Returns:
      A tuple of (probabilities, tree_paths, variance), where variance
      is the variance over all the trees for regression problems only.

    Raises:
      NotImplementedError: If trying to use feature bagging with sparse
        features.
    """
    processed_dense_features, processed_sparse_features, data_spec = (
        data_ops.ParseDataTensorOrDict(input_data))

    probabilities = []
    paths = []
    for i in range(self.params.num_trees):
      with ops.device(self.variables.device_dummies[i].device):
        tree_data = processed_dense_features
        if self.params.bagged_features:
          if processed_sparse_features is not None:
            raise NotImplementedError(
                'Feature bagging not supported with sparse features.')
          tree_data = self._bag_features(i, tree_data)
        probs, path = self.trees[i].inference_graph(
            tree_data,
            data_spec,
            sparse_features=processed_sparse_features,
            **inference_args)
        probabilities.append(probs)
        paths.append(path)
    with ops.device(self.variables.device_dummies[0].device):
      # shape of all_predict should be [batch_size, num_trees, num_outputs]
      all_predict = array_ops.stack(probabilities, axis=1)
      average_values = math_ops.div(
          math_ops.reduce_sum(all_predict, 1),
          self.params.num_trees,
          name='probabilities')
      tree_paths = array_ops.stack(paths, axis=1)
      regression_variance = None
      if self.params.regression:
        expected_squares = math_ops.div(
            math_ops.reduce_sum(all_predict * all_predict, 1),
            self.params.num_trees)
        regression_variance = math_ops.maximum(
            0., expected_squares - average_values * average_values)
      return average_values, tree_paths, regression_variance

def _DivGrad(op, grad):
  """The gradient for the Div operator."""
  x = op.inputs[0]
  y = op.inputs[1]
  sx = array_ops.shape(x)
  sy = array_ops.shape(y)
  rx, ry = gen_array_ops.broadcast_gradient_args(sx, sy)
  x = math_ops.conj(x)
  y = math_ops.conj(y)
  return (array_ops.reshape(math_ops.reduce_sum(math_ops.div(grad, y), rx), sx),
          array_ops.reshape(
              math_ops.reduce_sum(grad * math_ops.div(math_ops.div(-x, y), y),
                                  ry), sy))

  def _update_mask(self, weights, threshold):
    """Updates the mask for a given weight tensor.

    This functions first computes the cdf of the weight tensor, and estimates
    the threshold value such that 'desired_sparsity' fraction of weights
    have magnitude less than the threshold.

    Args:
      weights: The weight tensor that needs to be masked.
      threshold: The current threshold value. The function will compute a new
        threshold and return the exponential moving average using the current
        value of threshold

    Returns:
      new_threshold: The new value of the threshold based on weights, and
        sparsity at the current global_step
      new_mask: A numpy array of the same size and shape as weights containing
        0 or 1 to indicate which of the values in weights falls below
        the threshold

    Raises:
      ValueError: if sparsity is not defined
    """
    if self._sparsity is None:
      raise ValueError('Sparsity variable undefined')

    with ops.name_scope(weights.op.name + '_pruning_ops'):
      abs_weights = math_ops.abs(weights)
      max_value = math_ops.reduce_max(abs_weights)
      histogram = _histogram(
          abs_weights, [0.0, max_value],
          nbins=self._spec.nbins,
          dtype=np.float32)

      cdf = math_ops.cumsum(histogram)
      norm_cdf = math_ops.div(cdf, math_ops.reduce_sum(histogram))
      current_threshold = math_ops.multiply(
          math_ops.div(
              math_ops.reduce_sum(
                  math_ops.cast(
                      math_ops.less(norm_cdf, self._sparsity), np.float32)),
              float(self._spec.nbins)), max_value)

      smoothed_threshold = math_ops.add_n([
          math_ops.multiply(current_threshold, 1 - self._spec.threshold_decay),
          math_ops.multiply(threshold, self._spec.threshold_decay)
      ])
      new_mask = math_ops.cast(
          math_ops.greater(abs_weights, smoothed_threshold), np.float32)
    return smoothed_threshold, new_mask

def _DivGrad(op, grad):
  """The gradient for the Div operator."""
  x = op.inputs[0]
  y = op.inputs[1]
  sx = array_ops.shape(x)
  sy = array_ops.shape(y)
  # pylint: disable=protected-access
  rx, ry = gen_array_ops._broadcast_gradient_args(sx, sy)
  # pylint: enable=protected-access
  x = math_ops.conj(x)
  y = math_ops.conj(y)
  return (array_ops.reshape(math_ops.reduce_sum(math_ops.div(grad, y), rx), sx),
          array_ops.reshape(math_ops.reduce_sum(
              grad * math_ops.div(-x, math_ops.square(y)), ry), sy))

  def GetParams(self):
    """Create a graph containing multiple segment."""
    # TODO(aaroey): test graph with different dtypes.
    dtype = dtypes.float32
    input_name = "input"
    input_dims = [100, 24, 24, 2]
    g = ops.Graph()
    with g.as_default():
      inp = array_ops.placeholder(
          dtype=dtype, shape=[None] + input_dims[1:], name=input_name)
      with g.device("/GPU:0"):
        conv_filter = constant_op.constant(
            [[[[1., 0.5, 4., 6., 0.5, 1.], [1., 0.5, 1., 1., 0.5, 1.]]]],
            name="weights",
            dtype=dtype)
        conv = nn.conv2d(
            input=inp,
            filter=conv_filter,
            strides=[1, 2, 2, 1],
            padding="SAME",
            name="conv")
        c1 = constant_op.constant(
            np.random.randn(input_dims[0], 12, 12, 6), dtype=dtype, name="c1")
        p = math_ops.mul(conv, c1, name="mul")
        c2 = constant_op.constant(
            np.random.randn(input_dims[0], 12, 12, 6), dtype=dtype, name="c2")
        q = math_ops.div(conv, c2, name="div")

        edge = self.trt_incompatible_op(q, name="incompatible")
        edge = math_ops.div(edge, edge, name="div1")
        r = math_ops.add(edge, edge, name="add")

        p = math_ops.sub(p, edge, name="sub")
        q = math_ops.mul(q, edge, name="mul1")
        s = math_ops.add(p, q, name="add1")
        s = math_ops.sub(s, r, name="sub1")
      array_ops.squeeze(s, name=self.output_name)
    return trt_test.TfTrtIntegrationTestParams(
        gdef=g.as_graph_def(),
        input_names=[input_name],
        input_dims=[input_dims],
        # TODO(aaroey): LayoutOptimizer adds additional nodes to the graph which
        # breaks the connection check, fix it.
        # - my_trt_op_0 should have ["mul", "sub", "div1", "mul1", "add1",
        #   "add", "sub1"];
        # - my_trt_op_1 should have ["weights","conv", "div"]
        expected_engines=["my_trt_op_0", "my_trt_op_1"],
        expected_output_dims=(100, 12, 12, 6),
        allclose_atol=1.e-03,
        allclose_rtol=1.e-03)

def _safe_div(numerator, denominator, name="value"):
  """Computes a safe divide which returns 0 if the denominator is zero.

  Note that the function contains an additional conditional check that is
  necessary for avoiding situations where the loss is zero causing NaNs to
  creep into the gradient computation.

  Args:
    numerator: An arbitrary `Tensor`.
    denominator: A `Tensor` whose shape matches `numerator` and whose values are
      assumed to be non-negative.
    name: An optional name for the returned op.

  Returns:
    The element-wise value of the numerator divided by the denominator.
  """
  if compat.forward_compatible(2018, 11, 1):
    return math_ops.div_no_nan(numerator, denominator, name=name)
  return array_ops.where(
      math_ops.greater(denominator, 0),
      math_ops.div(numerator,
                   array_ops.where(
                       math_ops.equal(denominator, 0),
                       array_ops.ones_like(denominator), denominator)),
      array_ops.zeros_like(numerator),
      name=name)

def accuracy(predictions, labels, weights=None):
  """Computes the percentage of times that predictions matches labels.

  Args:
    predictions: the predicted values, a `Tensor` whose dtype and shape
                 matches 'labels'.
    labels: the ground truth values, a `Tensor` of any shape and
            bool, integer, or string dtype.
    weights: None or `Tensor` of float values to reweight the accuracy.

  Returns:
    Accuracy `Tensor`.

  Raises:
    ValueError: if dtypes don't match or
                if dtype is not bool, integer, or string.
  """
  if not (labels.dtype.is_integer or
          labels.dtype in (dtypes.bool, dtypes.string)):
    raise ValueError(
        'Labels should have bool, integer, or string dtype, not %r' %
        labels.dtype)
  if not labels.dtype.is_compatible_with(predictions.dtype):
    raise ValueError('Dtypes of predictions and labels should match. '
                     'Given: predictions (%r) and labels (%r)' %
                     (predictions.dtype, labels.dtype))
  with ops.name_scope('accuracy', values=[predictions, labels]):
    is_correct = math_ops.cast(
        math_ops.equal(predictions, labels), dtypes.float32)
    if weights is not None:
      is_correct = math_ops.mul(is_correct, weights)
      num_values = math_ops.mul(weights, array_ops.ones_like(is_correct))
      return math_ops.div(math_ops.reduce_sum(is_correct),
                          math_ops.reduce_sum(num_values))
    return math_ops.reduce_mean(is_correct)

def squared_loss(predicted, target, name=None):
  """Computes and returns the per-example squared loss, divided by 2.

  Computes the per-example squared difference between the target and
  predicted tensors. The tensors must have the same shape.

  Args:
    predicted: A `Tensor` of shape `[batch_size, dim_1, ..., dim_n]`
      of predicted values.
    target: A `Tensor` of shape `[batch_size, dim_1, ..., dim_n]` of
      target values. The shape of the target tensor should match the
      `predicted` tensor.
    name: A name for the operation (optional).

  Returns:
    A `[batch_size, dim_1, ..., dim_n]` tensor of per-example squared losses.

  Raises:
    ValueError: If `predicted` and `target` shapes do not match.

  """
  with ops.op_scope([predicted, target], name, "squared_loss") as scope:
    predicted = ops.convert_to_tensor(predicted, name="predicted")
    target = ops.convert_to_tensor(target, name="target")
    _validate_predicted_and_target(predicted, target)
    return math_ops.div(math_ops.square(target - predicted), 2.0, name=scope)

def weighted_moving_average(value,
                            decay,
                            weight,
                            truediv=True,
                            collections=None,
                            name=None):
  """Compute the weighted moving average of `value`.

  Conceptually, the weighted moving average is:
    `moving_average(value * weight) / moving_average(weight)`,
  where a moving average updates by the rule
    `new_value = decay * old_value + (1 - decay) * update`
  Internally, this Op keeps moving average variables of both `value * weight`
  and `weight`.

  Args:
    value: A numeric `Tensor`.
    decay: A float `Tensor` or float value.  The moving average decay.
    weight:  `Tensor` that keeps the current value of a weight.
      Shape should be able to multiply `value`.
    truediv:  Boolean, if `True`, dividing by `moving_average(weight)` is
      floating point division.  If `False`, use division implied by dtypes.
    collections:  List of graph collections keys to add the internal variables
      `value * weight` and `weight` to.
      Defaults to `[GraphKeys.GLOBAL_VARIABLES]`.
    name: Optional name of the returned operation.
      Defaults to "WeightedMovingAvg".

  Returns:
    An Operation that updates and returns the weighted moving average.
  """
  # Unlike assign_moving_average, the weighted moving average doesn't modify
  # user-visible variables. It is the ratio of two internal variables, which are
  # moving averages of the updates.  Thus, the signature of this function is
  # quite different than assign_moving_average.
  if collections is None:
    collections = [ops.GraphKeys.GLOBAL_VARIABLES]
  with variable_scope.variable_scope(name, "WeightedMovingAvg",
                                     [value, weight, decay]) as scope:
    value_x_weight_var = variable_scope.get_variable(
        "value_x_weight",
        initializer=init_ops.zeros_initializer(value.get_shape(),
                                               dtype=value.dtype),
        trainable=False,
        collections=collections)
    weight_var = variable_scope.get_variable(
        "weight",
        initializer=init_ops.zeros_initializer(weight.get_shape(),
                                               dtype=weight.dtype),
        trainable=False,
        collections=collections)
    numerator = assign_moving_average(
        value_x_weight_var, value * weight, decay, zero_debias=False)
    denominator = assign_moving_average(
        weight_var, weight, decay, zero_debias=False)

    if truediv:
      return math_ops.truediv(numerator, denominator, name=scope.name)
    else:
      return math_ops.div(numerator, denominator, name=scope.name)

  def setUp(self):
    self.a = variables.VariableV1(2.0, name="a")
    self.b = variables.VariableV1(3.0, name="b")

    self.c = math_ops.multiply(self.a, self.b, name="c")  # Should be 6.0.
    self.d = math_ops.multiply(self.a, self.a, name="d")  # Should be 4.0.

    self.e = math_ops.multiply(self.d, self.c, name="e")  # Should be 24.0.

    self.f_y = constant_op.constant(0.30, name="f_y")
    self.f = math_ops.div(self.b, self.f_y, name="f")  # Should be 10.0.

    # The there nodes x, y and z form a graph with "cross-links" in. I.e., x
    # and y are both direct inputs to z, but x is also a direct input to y.
    self.x = variables.VariableV1(2.0, name="x")  # Should be 2.0
    self.y = math_ops.negative(self.x, name="y")  # Should be -2.0.

    self.z = math_ops.multiply(self.x, self.y, name="z")  # Should be -4.0.

    rewriter_config = rewriter_config_pb2.RewriterConfig(
        disable_model_pruning=True,
        arithmetic_optimization=rewriter_config_pb2.RewriterConfig.OFF,
        constant_folding=rewriter_config_pb2.RewriterConfig.OFF)
    graph_options = config_pb2.GraphOptions(rewrite_options=rewriter_config)
    config = config_pb2.ConfigProto(graph_options=graph_options)
    self.sess = session.Session(config=config)
    self.sess.run(variables.global_variables_initializer())

  def loss(self, logits, target, features):
    """Returns loss tensor for this head.

    The loss returned is the weighted average.

      L = sum_{i} w_{i} * l_{i} / sum_{i} w_{i}

    Args:
      logits: logits, a float tensor.
      target: either a tensor for labels or in multihead case, a dict of string
        to target tensor.
      features: features dict.

    Returns:
      Loss tensor.
    """
    target = target[self.name] if isinstance(target, dict) else target
    loss_unweighted = self._loss_fn(logits, target)

    weight_tensor = self.get_weight_tensor(features)
    if weight_tensor is None:
      return math_ops.reduce_mean(loss_unweighted, name="loss")
    loss_weighted = self._weighted_loss(loss_unweighted, weight_tensor)
    return math_ops.div(
        math_ops.reduce_sum(loss_weighted),
        math_ops.cast(math_ops.reduce_sum(weight_tensor), dtypes.float32),
        name="loss")

  def loss(self, logits, target, features):
    """Returns loss tensor for this head.

    Args:
      logits: logits, a float tensor.
      target: either a tensor for labels or in multihead case, a dict of string
        to target tensor.
      features: features dict.

    Returns:
      Loss tensor.
    """
    target = target[self.name] if isinstance(target, dict) else target
    loss_unweighted = self._loss_fn(logits, target)

    weight_tensor = self.get_weight_tensor(features)
    if weight_tensor is None:
      return math_ops.reduce_mean(loss_unweighted, name="loss")
    else:
      loss_unweighted = array_ops.reshape(loss_unweighted, shape=(-1,))
      loss_weighted = math_ops.mul(
          loss_unweighted, array_ops.reshape(weight_tensor, shape=(-1,)))
      return math_ops.div(
          math_ops.reduce_sum(loss_weighted),
          math_ops.to_float(math_ops.reduce_sum(weight_tensor)),
          name="loss")