ai.djl.training.loss.IndexLoss Maven / Gradle / Ivy
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/*
* Copyright 2021 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License"). You may not use this file except in compliance
* with the License. A copy of the License is located at
*
* http://aws.amazon.com/apache2.0/
*
* or in the "license" file accompanying this file. This file is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES
* OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions
* and limitations under the License.
*/
package ai.djl.training.loss;
import ai.djl.ndarray.NDArray;
import ai.djl.ndarray.NDList;
/**
* A wrapper for a {@link Loss} that evaluates on only a particular {@link NDArray} in the
* predictions and/or labels {@link NDList}s.
*/
public class IndexLoss extends Loss {
private Loss loss;
private Integer predictionsIndex;
private Integer labelsIndex;
/**
* Constructs an {@link IndexLoss} with the same index for both predictions and labels.
*
* @param loss the base evaluator
* @param index the index for both predictions and labels
*/
public IndexLoss(Loss loss, int index) {
this(loss, index, index);
}
/**
* Constructs an {@link IndexLoss}.
*
* @param loss the base evaluator
* @param predictionsIndex the predictions index
* @param labelsIndex the labels index
*/
public IndexLoss(Loss loss, Integer predictionsIndex, Integer labelsIndex) {
super(loss.getName());
this.loss = loss;
this.predictionsIndex = predictionsIndex;
this.labelsIndex = labelsIndex;
}
/** {@inheritDoc} */
@Override
public NDArray evaluate(NDList labels, NDList predictions) {
return loss.evaluate(getLabels(labels), getPredictions(predictions));
}
private NDList getPredictions(NDList predictions) {
if (predictionsIndex == null) {
return predictions;
}
return new NDList(predictions.get(predictionsIndex));
}
private NDList getLabels(NDList labels) {
if (labelsIndex == null) {
return labels;
}
return new NDList(labels.get(labelsIndex));
}
}