/*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License 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 hivemall.classifier.multiclass;
import hivemall.model.FeatureValue;
import hivemall.model.Margin;
import javax.annotation.Nonnull;
import org.apache.commons.cli.CommandLine;
import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.UDFArgumentException;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.StructObjectInspector;
@Description(
name = "train_multiclass_pa",
value = "_FUNC_(list<string|int|bigint> features, {int|string} label [, const string options])"
+ " - Returns a relation consists of <{int|string} label, {string|int|bigint} feature, float weight>",
extended = "Build a prediction model by Passive-Aggressive (PA) multiclass classifier")
public class MulticlassPassiveAggressiveUDTF extends MulticlassOnlineClassifierUDTF {
@Override
public StructObjectInspector initialize(ObjectInspector[] argOIs) throws UDFArgumentException {
final int numArgs = argOIs.length;
if (numArgs != 2 && numArgs != 3) {
throw new UDFArgumentException(
"MulticlassPassiveAggressiveUDTF takes 2 or 3 arguments: List<Text|Int|BitInt> features, {Int|Text} label [, constant text options]");
}
return super.initialize(argOIs);
}
@Override
protected void train(@Nonnull final FeatureValue[] features, @Nonnull Object actual_label) {
Margin margin = getMargin(features, actual_label);
float loss = loss(margin);
if (loss > 0.f) { // & missed_label != null
float sqnorm = squaredNorm(features);
if (sqnorm == 0.f) {// avoid divide by zero
return;
}
float coeff = eta(loss, sqnorm);
Object missed_label = margin.getMaxIncorrectLabel();
update(features, coeff, actual_label, missed_label);
}
}
protected float loss(Margin margin) {
return 1.f - margin.get();
}
protected float eta(float loss, float sqnorm) {
return loss / (2.f * sqnorm);
}
@Description(
name = "train_multiclass_pa1",
value = "_FUNC_(list<string|int|bigint> features, {int|string} label [, const string options])"
+ " - Returns a relation consists of <{int|string} label, {string|int|bigint} feature, float weight>",
extended = "Build a prediction model by Passive-Aggressive 1 (PA-1) multiclass classifier")
public static class PA1 extends MulticlassPassiveAggressiveUDTF {
/** Aggressiveness parameter */
protected float c;
@Override
protected CommandLine processOptions(ObjectInspector[] argOIs) throws UDFArgumentException {
final CommandLine cl = super.processOptions(argOIs);
float c = 1.f;
if (cl != null) {
String c_str = cl.getOptionValue("c");
if (c_str != null) {
c = Float.parseFloat(c_str);
if (!(c > 0.f)) {
throw new UDFArgumentException("Aggressiveness parameter C must be C > 0: "
+ c);
}
}
}
this.c = c;
return cl;
}
@Override
protected float eta(float loss, float sqnorm) {
float eta = loss / (2.f * sqnorm);
return Math.min(c, eta);
}
}
@Description(
name = "train_multiclass_pa2",
value = "_FUNC_(list<string|int|bigint> features, {int|string} label [, const string options])"
+ " - Returns a relation consists of <{int|string} label, {string|int|bigint} feature, float weight>",
extended = "Build a prediction model by Passive-Aggressive 2 (PA-2) multiclass classifier")
public static final class PA2 extends PA1 {
@Override
protected float eta(float loss, float sqnorm) {
float eta = loss / ((2.f * sqnorm) + (0.5f / c));
return eta;
}
}
}