def unregularized_loss(self, examples):
"""Add operations to compute the loss (without the regularization loss).
Args:
examples: Examples to compute unregularized loss on.
Returns:
An Operation that computes mean (unregularized) loss for given set of
examples.
Raises:
ValueError: if examples are not well defined.
"""
self._assertSpecified(['example_labels', 'example_weights',
'sparse_features', 'dense_features'], examples)
self._assertList(['sparse_features', 'dense_features'], examples)
with name_scope('sdca/unregularized_loss'):
predictions = math_ops.cast(
self._linear_predictions(examples), dtypes.float64)
labels = math_ops.cast(
convert_to_tensor(examples['example_labels']), dtypes.float64)
weights = math_ops.cast(
convert_to_tensor(examples['example_weights']), dtypes.float64)
if self._options['loss_type'] == 'logistic_loss':
return math_ops.reduce_sum(math_ops.mul(
sigmoid_cross_entropy_with_logits(predictions, labels),
weights)) / math_ops.reduce_sum(weights)
if self._options['loss_type'] in ['hinge_loss', 'smooth_hinge_loss']:
# hinge_loss = max{0, 1 - y_i w*x} where y_i \in {-1, 1}. So, we need to
# first convert 0/1 labels into -1/1 labels.
all_ones = array_ops.ones_like(predictions)
adjusted_labels = math_ops.sub(2 * labels, all_ones)
# Tensor that contains (unweighted) error (hinge loss) per
# example.
error = nn_ops.relu(math_ops.sub(all_ones, math_ops.mul(adjusted_labels,
predictions)))
weighted_error = math_ops.mul(error, weights)
return math_ops.reduce_sum(weighted_error) / math_ops.reduce_sum(
weights)
# squared loss
err = math_ops.sub(labels, predictions)
weighted_squared_err = math_ops.mul(math_ops.square(err), weights)
# SDCA squared loss function is sum(err^2) / (2*sum(weights))
return (math_ops.reduce_sum(weighted_squared_err) /
(2.0 * math_ops.reduce_sum(weights)))
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