Python math_ops.abs函数代码示例

def _ForUsingWhile(start,
                   limit,
                   delta,
                   inputs,
                   forbody,
                   name=None,
                   hostmem=None):
  """Helper to implement a For loop using a While."""
  # To support negative delta (e.g., range(100, 0, -3)), we iterate
  # over the range(n) and use iter * delta + start as the real
  # iteration index. (e.g., for i in range(34): iter = i * (-3) +
  # 100).
  d = math_ops.abs(delta)
  # XLA on TPUs doesn't support integer division
  n = math_ops.cast(
      math_ops.cast((math_ops.abs(limit - start) + d - 1), dtypes.float32) /
      math_ops.cast(d, dtypes.float32), dtypes.int32)

  # Carried loop variables ("extra_args") are implicitly added to the input list
  # of the WhileBody function. WhileCond does not call forbody, and so does not
  # depend on any of forbody's extra_args. Since WhileCond and WhileBody
  # must have identical inputs, we have to augment the cond signature to take
  # the same types as the carried loop variables.
  body_sig = [dtypes.int32] * 4 + list(forbody.declared_input_types)[1:]

  cond_name = "%s_Cond" % forbody.name

  @function.Defun(*body_sig, func_name=cond_name)
  def WhileCond(i, n, *args):
    del args
    return i < n

  body_name = "%s_Body" % forbody.name

  @function.Defun(*body_sig, func_name=body_name)
  def WhileBody(i, n, start, delta, *args):
    """A While wrapper for forbody that handles loop-carried captured inputs."""
    for_result = forbody(start + i * delta, *args)
    # Nullary functions return an Operation. Normal functions can't do this
    # because their return values are converted to Tensors.
    if isinstance(for_result, ops.Operation):
      for_result = ()
    # Unary functions return a single Tensor value.
    elif isinstance(for_result, ops.Tensor):
      for_result = (for_result,)
    return (i + 1, n, start, delta) + tuple(for_result)

  if hostmem is not None:
    hostmem = [0, 1, 2, 3] + [(4 + _) for _ in hostmem]
  else:
    hostmem = [0, 1, 2, 3]

  results = While(
      input_=[0, n, start, delta] + inputs,
      cond=WhileCond,
      body=WhileBody,
      name=name,
      hostmem=hostmem)
  # Slice off the loop-carried captured inputs.
  return list(results[4:len(results)])

 def GetParams(self):
   """Test for rank 2 input in TF-TRT."""
   input_names = ["input", "input2"]
   # Two paths: first with rank 2 input, second with rank 4 input.
   input_dims = [[12, 5], [12, 5, 2, 2]]
   output_name = "output"
   g = ops.Graph()
   with g.as_default():
     outputs = []
     for i in range(2):
       x = array_ops.placeholder(
           dtype=dtypes.float32, shape=input_dims[i], name=input_names[i])
       c = constant_op.constant(1.0, name="c%d_1" % i)
       q = math_ops.add(x, c, name="add%d_1" % i)
       q = math_ops.abs(q, name="abs%d_1" % i)
       c = constant_op.constant(2.2, name="c%d_2" % i)
       q = math_ops.add(q, c, name="add%d_2" % i)
       q = math_ops.abs(q, name="abs%d_2" % i)
       c = constant_op.constant(3.0, name="c%d_3" % i)
       q = math_ops.add(q, c, name="add%d_3" % i)
       if i == 0:
         for j in range(2):
           q = array_ops.expand_dims(q, -1, name="expand%d_%d" % (i, j))
       q = gen_math_ops.reciprocal(q, name="reciprocal%d" % i)
       outputs.append(q)
     # Combine both paths
     q = math_ops.add(outputs[0], outputs[1], name="add")
     array_ops.squeeze(q, name=output_name)
   return trt_test.TfTrtIntegrationTestParams(
       gdef=g.as_graph_def(),
       input_names=input_names,
       input_dims=input_dims,
       output_names=[output_name],
       expected_output_dims=[tuple(input_dims[1])])

def _assert_close(expected, actual, rtol=1e-04, name='assert_close'):
  with ops.name_scope(name, 'assert_close', (expected, actual, rtol)) as scope:
    expected = ops.convert_to_tensor(expected, name='expected')
    actual = ops.convert_to_tensor(actual, name='actual')
    rdiff = math_ops.abs(expected - actual, 'diff') / math_ops.abs(expected)
    rtol = ops.convert_to_tensor(rtol, name='rtol')
    return check_ops.assert_less(
        rdiff,
        rtol,
        data=('Condition expected =~ actual did not hold element-wise:'
              'expected = ', expected, 'actual = ', actual, 'rdiff = ', rdiff,
              'rtol = ', rtol,),
        name=scope)

 def _apply_sparse_shared(self, grad, var, indices,
                          scatter_add, scatter_update):
   beta1_power = self._get_beta_accumulators()
   beta1_power = math_ops.cast(beta1_power, var.dtype.base_dtype)
   lr_t = math_ops.cast(self._lr_t, var.dtype.base_dtype)
   beta1_t = math_ops.cast(self._beta1_t, var.dtype.base_dtype)
   beta2_t = math_ops.cast(self._beta2_t, var.dtype.base_dtype)
   epsilon_t = math_ops.cast(self._epsilon_t, var.dtype.base_dtype)
   # m_t = beta1 * m + (1 - beta1) * g_t
   m = self.get_slot(var, "m")
   m_slice = array_ops.gather(m, indices)
   m_t_slice = m_slice * beta1_t + grad * (1 - beta1_t)
   with ops.control_dependencies([m_t_slice]):
     m_t = scatter_update(m, indices, m_t_slice)
   # u_t = max(beta2 * u, abs(g_t))
   v = self.get_slot(var, "v")
   v_slice = array_ops.gather(v, indices)
   v_t_slice = math_ops.maximum(v_slice * beta2_t, math_ops.abs(grad))
   with ops.control_dependencies([v_t_slice]):
     v_t = scatter_update(v, indices, v_t_slice)
   # theta_t = theta - lr / (1 - beta1^t) * m_t / u_t
   var_slice = -lr_t / (1 - beta1_power) * (m_t_slice /
                                            (v_t_slice + epsilon_t))
   with ops.control_dependencies([var_slice]):
     var_update = scatter_add(var, indices, var_slice)
   return control_flow_ops.group(*[var_update, m_t, v_t])

def absolute_loss(predicted, target, name=None):
  """Computes and returns the per-example absolute loss.

  Computes the per-example absolute value of the 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 absolute losses.

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

  """
  with ops.op_scope([predicted, target], name, "absolute_loss") as scope:
    predicted = ops.convert_to_tensor(predicted, name="predicted")
    target = ops.convert_to_tensor(target, name="target")
    predicted.get_shape().assert_is_compatible_with(target.get_shape())
    return math_ops.abs(target - predicted, name=scope)

  def __call__(self, shape, dtype=None, partition_info=None):
    if dtype is None:
      dtype = self.dtype
    # Check the shape
    if len(shape) < 2:
      raise ValueError("The tensor to initialize must be "
                       "at least two-dimensional")
    # Flatten the input shape with the last dimension remaining
    # its original shape so it works for conv2d
    num_rows = 1
    for dim in shape[:-1]:
      num_rows *= dim
    num_cols = shape[-1]
    flat_shape = (num_rows, num_cols)

    # Generate a random matrix
    a = random_ops.random_normal(flat_shape, dtype=dtype, seed=self.seed)
    # Compute the qr factorization
    q, r = linalg_ops.qr(a, full_matrices=False)
    # Make Q uniform
    square_len = math_ops.minimum(num_rows, num_cols)
    d = array_ops.diag_part(r[:square_len, :square_len])
    ph = d / math_ops.abs(d)
    q *= ph
    # Pad zeros to Q (if rows smaller than cols)
    if num_rows < num_cols:
      padding = array_ops.zeros([num_rows, num_cols - num_rows], dtype=dtype)
      q = array_ops.concat([q, padding], 1)
    return self.gain * array_ops.reshape(q, shape)

  def _resource_apply_sparse(self, grad, var, indices):
    var_dtype = var.dtype.base_dtype
    lr_t = self._decayed_lr(var_dtype)

    beta_1_t = self._get_hyper('beta_1', var_dtype)
    beta_2_t = self._get_hyper('beta_2', var_dtype)
    local_step = math_ops.cast(self.iterations + 1, var_dtype)
    beta_1_power = math_ops.pow(beta_1_t, local_step)
    epsilon_t = self._get_hyper('epsilon', var_dtype)

    # m_t = beta1 * m + (1 - beta1) * g_t
    m = self.get_slot(var, 'm')
    m_slice = array_ops.gather(m, indices)
    m_t_slice = m_slice * beta_1_t + grad * (1 - beta_1_t)
    with ops.control_dependencies([m_t_slice]):
      m_t = self._resource_scatter_update(m, indices, m_t_slice)

    # u_t = max(beta2 * u, abs(g_t))
    v = self.get_slot(var, 'v')
    v_slice = array_ops.gather(v, indices)
    v_t_slice = math_ops.maximum(v_slice * beta_2_t, math_ops.abs(grad))
    with ops.control_dependencies([v_t_slice]):
      v_t = self._resource_scatter_update(v, indices, v_t_slice)
    # theta_t = theta - lr / (1 - beta1^t) * m_t / u_t
    var_slice = -lr_t / (1 - beta_1_power) * (
        m_t_slice / (v_t_slice + epsilon_t))
    with ops.control_dependencies([var_slice]):
      var_update = self._resource_scatter_add(var, indices, var_slice)
    return control_flow_ops.group(*[var_update, m_t, v_t])

def assert_close(
    x, y, data=None, summarize=None, message=None, name="assert_close"):
  """Assert that that x and y are within machine epsilon of each other.

  Args:
    x: Numeric `Tensor`
    y: Numeric `Tensor`
    data: The tensors to print out if the condition is `False`. Defaults to
      error message and first few entries of `x` and `y`.
    summarize: Print this many entries of each tensor.
    message: A string to prefix to the default message.
    name: A name for this operation (optional).

  Returns:
    Op raising `InvalidArgumentError` if |x - y| > machine epsilon.
  """
  message = message or ""
  x = ops.convert_to_tensor(x, name="x")
  y = ops.convert_to_tensor(y, name="y")

  if x.dtype.is_integer:
    return check_ops.assert_equal(
        x, y, data=data, summarize=summarize, message=message, name=name)

  with ops.name_scope(name, "assert_close", [x, y, data]):
    tol = np.finfo(x.dtype.as_numpy_dtype).resolution
    if data is None:
      data = [
          message,
          "Condition x ~= y did not hold element-wise: x = ", x.name, x, "y = ",
          y.name, y
      ]
    condition = math_ops.reduce_all(math_ops.less_equal(math_ops.abs(x-y), tol))
    return control_flow_ops.Assert(
        condition, data, summarize=summarize)

def exact_laplacian_kernel(x, y, stddev):
  """Computes exact Laplacian kernel value(s) for tensors x and y using stddev.

  The Laplacian kernel for vectors u, v is defined as follows:
       K(u, v) = exp(-||u-v|| / stddev)
  where the norm is the l1-norm. x, y can be either vectors or matrices. If they
  are vectors, they must have the same dimension. If they are matrices, they
  must have the same number of columns. In the latter case, the method returns
  (as a matrix) K(u, v) values for all pairs (u, v) where u is a row from x and
  v is a row from y.

  Args:
    x: a tensor of rank 1 or 2. It's shape should be either [dim] or [m, dim].
    y: a tensor of rank 1 or 2. It's shape should be either [dim] or [n, dim].
    stddev: The width of the Gaussian kernel.

  Returns:
    A single value (scalar) with shape (1, 1)  if x, y are vectors or a matrix
    of shape (m, n) with entries K(u, v) (where K is the Laplacian kernel) for
    all (u,v) pairs where u, v are rows from x and y respectively.

  Raises:
    InvalidShapeError: if the shapes of x, y are not compatible.
  """
  x_aligned, y_aligned = _align_matrices(x, y)
  diff_l1_norm = math_ops.reduce_sum(
      math_ops.abs(math_ops.subtract(x_aligned, y_aligned)), 2)
  return math_ops.exp(-diff_l1_norm / stddev)

 def __call__(self, x):
   regularization = 0.
   if self.l1:
     regularization += math_ops.reduce_sum(self.l1 * math_ops.abs(x))
   if self.l2:
     regularization += math_ops.reduce_sum(self.l2 * math_ops.square(x))
   return regularization

 def testChi2WithAbsDf(self):
   with self.cached_session():
     df_v = np.array([-1.3, -3.2, 5], dtype=np.float64)
     chi2 = chi2_lib.Chi2WithAbsDf(df=df_v)
     self.assertAllClose(
         math_ops.floor(math_ops.abs(df_v)).eval(),
         chi2.df.eval())

  def __call__(self, shape, dtype=None, partition_info=None):
    if dtype is None:
      dtype = self.dtype
    # Check the shape
    if len(shape) < 2:
      raise ValueError("The tensor to initialize must be "
                       "at least two-dimensional")
    # Flatten the input shape with the last dimension remaining
    # its original shape so it works for conv2d
    num_rows = 1
    for dim in shape[:-1]:
      num_rows *= dim
    num_cols = shape[-1]
    flat_shape = (num_cols, num_rows) if num_rows < num_cols else (num_rows,
                                                                   num_cols)

    # Generate a random matrix
    a = random_ops.random_normal(flat_shape, dtype=dtype, seed=self.seed)
    # Compute the qr factorization
    q, r = linalg_ops.qr(a, full_matrices=False)
    # Make Q uniform
    d = array_ops.diag_part(r)
    ph = d / math_ops.abs(d)
    q *= ph
    if num_rows < num_cols:
      q = array_ops.matrix_transpose(q)
    return self.gain * array_ops.reshape(q, shape)

  def test_bad_kernel_approximation(self, initializer, scale, exact_kernel_fn):
    """Approximation is bad when output dimension is small."""
    # Two distinct inputs.
    x = constant_op.constant([[1.0, -1.0, 0.5]])
    y = constant_op.constant([[-1.0, 1.0, 1.0]])

    small_output_dim = 10
    random_seed.set_random_seed(1234)
    # Initialize layer.
    rff_layer = kernel_layers.RandomFourierFeatures(
        output_dim=small_output_dim,
        kernel_initializer=initializer,
        scale=scale,
        name='random_fourier_features')

    # Apply layer to both inputs.
    output_x = math.sqrt(2.0 / small_output_dim) * rff_layer.apply(x)
    output_y = math.sqrt(2.0 / small_output_dim) * rff_layer.apply(y)

    # The inner products of the outputs (on inputs x and y) approximates the
    # real value of the RBF kernel but poorly since the output dimension of the
    # layer is small.
    exact_kernel_value = exact_kernel_fn(x, y)
    approx_kernel_value = kernelized_utils.inner_product(output_x, output_y)
    abs_error = math_ops.abs(exact_kernel_value - approx_kernel_value)
    if not context.executing_eagerly():
      with self.cached_session() as sess:
        keras_backend._initialize_variables(sess)
        abs_error_eval = sess.run([abs_error])
        self.assertGreater(abs_error_eval[0][0], 0.05)
        self.assertLess(abs_error_eval[0][0], 0.5)
    else:
      self.assertGreater(abs_error, 0.05)
      self.assertLess(abs_error, 0.5)

def huber_loss(labels, predictions, weights=1.0, delta=1.0, scope=None,
               loss_collection=ops.GraphKeys.LOSSES,
               reduction=Reduction.WEIGHTED_SUM_BY_NONZERO_WEIGHTS):
  """Adds a Huber Loss term to the training procedure.

  For each value x in `error=labels-predictions`, the following is calculated:

  ```
    0.5 * x^2                  if |x| <= d
    0.5 * d^2 + d * (|x| - d)  if |x| > d
  ```

  where d is `delta`.

  See: https://en.wikipedia.org/wiki/Huber_loss

  `weights` acts as a coefficient for the loss. If a scalar is provided, then
  the loss is simply scaled by the given value. If `weights` is a tensor of size
  [batch_size], then the total loss for each sample of the batch is rescaled
  by the corresponding element in the `weights` vector. If the shape of
  `weights` matches the shape of `predictions`, then the loss of each
  measurable element of `predictions` is scaled by the corresponding value of
  `weights`.

  Args:
    labels: The ground truth output tensor, same dimensions as 'predictions'.
    predictions: The predicted outputs.
    weights: Optional `Tensor` whose rank is either 0, or the same rank as
      `labels`, and must be broadcastable to `labels` (i.e., all dimensions must
      be either `1`, or the same as the corresponding `losses` dimension).
    delta: `float`, the point where the huber loss function
      changes from a quadratic to linear.
    scope: The scope for the operations performed in computing the loss.
    loss_collection: collection to which the loss will be added.
    reduction: Type of reduction to apply to loss.

  Returns:
    A scalar `Tensor` that returns the weighted loss.

  Raises:
    ValueError: If the shape of `predictions` doesn't match that of `labels` or
      if the shape of `weights` is invalid.
  """
  with ops.name_scope(scope, "huber_loss",
                      (predictions, labels, weights)) as scope:
    predictions = math_ops.to_float(predictions)
    labels = math_ops.to_float(labels)
    predictions.get_shape().assert_is_compatible_with(labels.get_shape())
    error = math_ops.subtract(predictions, labels)
    abs_error = math_ops.abs(error)
    quadratic = math_ops.minimum(abs_error, delta)
    # The following expression is the same in value as
    # tf.maximum(abs_error - delta, 0), but importantly the gradient for the
    # expression when abs_error == delta is 0 (for tf.maximum it would be 1).
    # This is necessary to avoid doubling the gradient, since there is already a
    # nonzero contribution to the gradient from the quadratic term.
    linear = (abs_error - quadratic)
    losses = 0.5 * quadratic**2 + delta * linear
    return compute_weighted_loss(
        losses, weights, scope, loss_collection, reduction=reduction)

    def inner_loss(y_true, y_pred):
        delta = math_ops.abs(math_ops.subtract(y_pred, y_true))
        losses = math_ops.square(delta)
        if clip > 0.0:
            losses = tf.where(delta < clip, 0.5 * losses, delta - 0.5)

        return losses