tf.contrib.kfac.loss_functions.CategoricalLogitsNegativeLogProbLoss

Class CategoricalLogitsNegativeLogProbLoss

Inherits From: DistributionNegativeLogProbLoss, NaturalParamsNegativeLogProbLoss

Defined in tensorflow/contrib/kfac/python/ops/loss_functions.py.

Neg log prob loss for a categorical distribution parameterized by logits.

Note that the Fisher (for a single case) of a categorical distribution, with respect to the natural parameters (i.e. the logits), is given by:

F = diag(p) - p*p^T

where p = softmax(logits). F can be factorized as F = B * B^T where

B = diag(q) - p*q^T

where q is the entry-wise square root of p. This is easy to verify using the fact that q^T*q = 1.

Properties

dist

The underlying tf.distributions.Distribution.

fisher_factor_inner_shape

The shape of the tensor returned by multiply_fisher_factor.

fisher_factor_inner_static_shape

Static version of fisher_factor_inner_shape.

hessian_factor_inner_shape

The shape of the tensor returned by multiply_hessian_factor.

hessian_factor_inner_static_shape

Static version of hessian_factor_inner_shape.

inputs

The inputs to the loss function (excluding the targets).

params

Parameters to the underlying distribution.

targets

The targets being predicted by the model.

Returns:

None or Tensor of appropriate shape for calling self._evaluate() on.

Methods

__init__

__init__(
    logits,
    targets=None,
    seed=None
)

Instantiates a CategoricalLogitsNegativeLogProbLoss.

Args:

• logits: Tensor of shape [batch_size, output_size]. Parameters for underlying distribution.
• targets: None or Tensor of shape [output_size]. Each elements contains an index in [0, output_size).
• seed: int or None. Default random seed when sampling.

evaluate

evaluate()

Evaluate the loss function on the targets.

evaluate_on_sample

evaluate_on_sample(seed=None)

Evaluates the log probability on a random sample.

Args:

• seed: int or None. Random seed for this draw from the distribution.

Returns:

Log probability of sampled targets, summed across examples.

multiply_fisher

multiply_fisher(vector)

Right-multiply a vector by the Fisher.

Args:

• vector: The vector to multiply. Must be the same shape(s) as the 'inputs' property.

Returns:

The vector right-multiplied by the Fisher. Will be of the same shape(s) as the 'inputs' property.

multiply_fisher_factor

multiply_fisher_factor(vector)

Right-multiply a vector by a factor B of the Fisher.

Here the 'Fisher' is the Fisher information matrix (i.e. expected outer- product of gradients) with respect to the parameters of the underlying probability distribtion (whose log-prob defines the loss). Typically this will be block-diagonal across different cases in the batch, since the distribution is usually (but not always) conditionally iid across different cases.

Note that B can be any matrix satisfying B * B^T = F where F is the Fisher, but will agree with the one used in the other methods of this class.

Args:

• vector: The vector to multiply. Must be of the shape given by the 'fisher_factor_inner_shape' property.

Returns:

The vector right-multiplied by B. Will be of the same shape(s) as the 'inputs' property.

multiply_fisher_factor_replicated_one_hot

multiply_fisher_factor_replicated_one_hot(index)

Right-multiply a replicated-one-hot vector by a factor B of the Fisher.

Here the 'Fisher' is the Fisher information matrix (i.e. expected outer- product of gradients) with respect to the parameters of the underlying probability distribtion (whose log-prob defines the loss). Typically this will be block-diagonal across different cases in the batch, since the distribution is usually (but not always) conditionally iid across different cases.

A 'replicated-one-hot' vector means a tensor which, for each slice along the batch dimension (assumed to be dimension 0), is 1.0 in the entry corresponding to the given index and 0 elsewhere.

Note that B can be any matrix satisfying B * B^T = H where H is the Fisher, but will agree with the one used in the other methods of this class.

Args:

• index: A tuple representing in the index of the entry in each slice that is 1.0. Note that len(index) must be equal to the number of elements of the 'fisher_factor_inner_shape' tensor minus one.

Returns:

The vector right-multiplied by B. Will be of the same shape(s) as the 'inputs' property.

multiply_fisher_factor_transpose

multiply_fisher_factor_transpose(vector)

Right-multiply a vector by the transpose of a factor B of the Fisher.

Here the 'Fisher' is the Fisher information matrix (i.e. expected outer- product of gradients) with respect to the parameters of the underlying probability distribtion (whose log-prob defines the loss). Typically this will be block-diagonal across different cases in the batch, since the distribution is usually (but not always) conditionally iid across different cases.

Note that B can be any matrix satisfying B * B^T = F where F is the Fisher, but will agree with the one used in the other methods of this class.

Args:

• vector: The vector to multiply. Must be the same shape(s) as the 'inputs' property.

Returns:

The vector right-multiplied by B^T. Will be of the shape given by the 'fisher_factor_inner_shape' property.

multiply_hessian

multiply_hessian(vector)

Right-multiply a vector by the Hessian.

Here the 'Hessian' is the Hessian matrix (i.e. matrix of 2nd-derivatives) of the loss function with respect to its inputs.

Args:

• vector: The vector to multiply. Must be the same shape(s) as the 'inputs' property.

Returns:

The vector right-multiplied by the Hessian. Will be of the same shape(s) as the 'inputs' property.

multiply_hessian_factor

multiply_hessian_factor(vector)

Right-multiply a vector by a factor B of the Hessian.

Here the 'Hessian' is the Hessian matrix (i.e. matrix of 2nd-derivatives) of the loss function with respect to its inputs. Typically this will be block-diagonal across different cases in the batch, since the loss function is typically summed across cases.

Note that B can be any matrix satisfying B * B^T = H where H is the Hessian, but will agree with the one used in the other methods of this class.

Args:

• vector: The vector to multiply. Must be of the shape given by the 'hessian_factor_inner_shape' property.

Returns:

The vector right-multiplied by B. Will be of the same shape(s) as the 'inputs' property.

multiply_hessian_factor_replicated_one_hot

multiply_hessian_factor_replicated_one_hot(index)

Right-multiply a replicated-one-hot vector by a factor B of the Hessian.

Here the 'Hessian' is the Hessian matrix (i.e. matrix of 2nd-derivatives) of the loss function with respect to its inputs. Typically this will be block-diagonal across different cases in the batch, since the loss function is typically summed across cases.

A 'replicated-one-hot' vector means a tensor which, for each slice along the batch dimension (assumed to be dimension 0), is 1.0 in the entry corresponding to the given index and 0 elsewhere.

Note that B can be any matrix satisfying B * B^T = H where H is the Hessian, but will agree with the one used in the other methods of this class.

Args:

• index: A tuple representing in the index of the entry in each slice that is 1.0. Note that len(index) must be equal to the number of elements of the 'hessian_factor_inner_shape' tensor minus one.

Returns:

The vector right-multiplied by B^T. Will be of the same shape(s) as the 'inputs' property.

multiply_hessian_factor_transpose

multiply_hessian_factor_transpose(vector)

Right-multiply a vector by the transpose of a factor B of the Hessian.

Here the 'Hessian' is the Hessian matrix (i.e. matrix of 2nd-derivatives) of the loss function with respect to its inputs. Typically this will be block-diagonal across different cases in the batch, since the loss function is typically summed across cases.

Note that B can be any matrix satisfying B * B^T = H where H is the Hessian, but will agree with the one used in the other methods of this class.

Args:

• vector: The vector to multiply. Must be the same shape(s) as the 'inputs' property.

Returns:

The vector right-multiplied by B^T. Will be of the shape given by the 'hessian_factor_inner_shape' property.

sample

sample(seed)

Sample 'targets' from the underlying distribution.