ai.djl.training.tracker.FactorTracker 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.tracker;
import ai.djl.util.Preconditions;
/**
* {@code FactorTracker} is an implementation of {@link Tracker} which is updated by a
* multiplicative factor.
*
* @see For
* tracking learning rates, this section in the D2L chapter on learning rate scheduling
*/
public class FactorTracker implements Tracker {
private float baseValue;
private float factor;
private int maxUpdates;
/**
* Creates a new instance of {@code FactorTracker}.
*
* @param builder the builder to create a new instance of {@code FactorTracker}
*/
public FactorTracker(Builder builder) {
this.baseValue = builder.baseValue;
this.factor = builder.factor;
this.maxUpdates = builder.maxUpdates;
}
/**
* Creates a new builder.
*
* @return a new builder
*/
public static Builder builder() {
return new Builder();
}
/** {@inheritDoc} */
@Override
public float getNewValue(int numUpdate) {
if (numUpdate > maxUpdates) {
numUpdate = maxUpdates;
}
return (float) (baseValue * Math.pow(factor, numUpdate));
}
/** The Builder to construct an {@link FactorTracker} object. */
public static final class Builder {
private float baseValue;
private float factor;
Float min;
Integer maxUpdates;
private Builder() {}
/**
* Sets the initial value after no steps.
*
* @param baseValue the initial value
* @return this {@code Builder}
*/
public Builder setBaseValue(float baseValue) {
this.baseValue = baseValue;
return this;
}
/**
* Sets the value of the multiplicative factor.
*
* @param factor the value of the multiplicative factor
* @return this {@code Builder}
*/
public Builder setFactor(float factor) {
if (factor > 1f) {
throw new IllegalArgumentException("factor should be no more than 1");
}
this.factor = factor;
return this;
}
/**
* Sets the minimum value.
*
* This is equivalent to the max updates. Only one can be set.
*
* @param min the minimum value
* @return this {@code Builder}
*/
public Builder optMinValue(float min) {
this.min = min;
return this;
}
/**
* Sets the maximum number of updates after which the value should remain constant.
*
* @param maxUpdates the maximum number of updates after which the value should remain
* constant
* @return this {@code Builder}
*/
public Builder optMaxUpdates(int maxUpdates) {
this.maxUpdates = maxUpdates;
return this;
}
/**
* Builds a {@link FactorTracker} block.
*
* @return the {@link FactorTracker} block
*/
public FactorTracker build() {
Preconditions.checkArgument(factor != 0, "You must set a factor");
if (min != null) {
Preconditions.checkArgument(
maxUpdates == null, "You can not set both maxUpdates and a min value");
Preconditions.checkArgument(
min < baseValue, "The min must be smaller than the base value");
maxUpdates =
Math.toIntExact(Math.round(Math.log(min / baseValue) / Math.log(factor)));
} else if (maxUpdates == null) {
// Default to no max if none set
maxUpdates = Integer.MAX_VALUE;
}
return new FactorTracker(this);
}
}
}