ai.djl.training.evaluator.AbstractAccuracy Maven / Gradle / Ivy
/*
* Copyright 2019 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.evaluator;
import ai.djl.ndarray.NDArray;
import ai.djl.ndarray.NDList;
import ai.djl.util.Pair;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
/**
* {@code Accuracy} is an {@link Evaluator} that computes the accuracy score.
*
* The accuracy score is defined as \(accuracy(y, \hat{y}) =
* \frac{1}{n}\sum_{i=0}^{n-1}1(\hat{y_i} == y_i)\)
*/
public abstract class AbstractAccuracy extends Evaluator {
protected Map correctInstances;
protected int axis;
/**
* Creates an accuracy evaluator that computes accuracy across axis 1.
*
* @param name the name of the evaluator, default is "Accuracy"
*/
public AbstractAccuracy(String name) {
this(name, 1);
}
/**
* Creates an accuracy evaluator.
*
* @param name the name of the evaluator, default is "Accuracy"
* @param axis the axis that represent classes in prediction, default 1
*/
public AbstractAccuracy(String name, int axis) {
super(name);
correctInstances = new ConcurrentHashMap<>();
this.axis = axis;
}
/**
* A helper for classes extending {@link AbstractAccuracy}.
*
* @param labels the labels to get accuracy for
* @param predictions the predictions to get accuracy for
* @return a pair(number of total values, ndarray int of correct values)
*/
protected abstract Pair accuracyHelper(NDList labels, NDList predictions);
/** {@inheritDoc} */
@Override
public NDArray evaluate(NDList labels, NDList predictions) {
return accuracyHelper(labels, predictions).getValue();
}
/** {@inheritDoc} */
@Override
public void addAccumulator(String key) {
totalInstances.put(key, 0L);
correctInstances.put(key, 0L);
}
/** {@inheritDoc} */
@Override
public void updateAccumulator(String key, NDList labels, NDList predictions) {
Pair update = accuracyHelper(labels, predictions);
totalInstances.compute(key, (k, v) -> v + update.getKey());
correctInstances.compute(key, (k, v) -> v + update.getValue().sum().getLong());
}
/** {@inheritDoc} */
@Override
public void resetAccumulator(String key) {
totalInstances.compute(key, (k, v) -> 0L);
correctInstances.compute(key, (k, v) -> 0L);
}
/** {@inheritDoc} */
@Override
public float getAccumulator(String key) {
Long total = totalInstances.get(key);
if (total == null || total == 0) {
return Float.NaN;
}
return (float) correctInstances.get(key) / totalInstances.get(key);
}
}