/*
* 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.knn.distance;
import hivemall.model.FeatureValue;
import hivemall.utils.hadoop.HiveUtils;
import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.UDFArgumentException;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.udf.UDFType;
import org.apache.hadoop.hive.ql.udf.generic.GenericUDF;
import org.apache.hadoop.hive.serde2.objectinspector.ListObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
import org.apache.hadoop.io.FloatWritable;
@Description(name = "manhattan_distance", value = "_FUNC_(list x, list y) - Returns sum(|x - y|)")
@UDFType(deterministic = true, stateful = false)
public final class ManhattanDistanceUDF extends GenericUDF {
private ListObjectInspector arg0ListOI, arg1ListOI;
@Override
public ObjectInspector initialize(ObjectInspector[] argOIs) throws UDFArgumentException {
if (argOIs.length != 2) {
throw new UDFArgumentException("manhattan_distance takes 2 arguments");
}
this.arg0ListOI = HiveUtils.asListOI(argOIs[0]);
this.arg1ListOI = HiveUtils.asListOI(argOIs[1]);
return PrimitiveObjectInspectorFactory.writableFloatObjectInspector;
}
@Override
public FloatWritable evaluate(DeferredObject[] arguments) throws HiveException {
List<String> ftvec1 = HiveUtils.asStringList(arguments[0], arg0ListOI);
List<String> ftvec2 = HiveUtils.asStringList(arguments[1], arg1ListOI);
float d = (float) manhattanDistance(ftvec1, ftvec2);
return new FloatWritable(d);
}
public static double manhattanDistance(final List<String> ftvec1, final List<String> ftvec2) {
final FeatureValue probe = new FeatureValue();
final Map<String, Float> map = new HashMap<String, Float>(ftvec1.size() * 2 + 1);
for (String ft : ftvec1) {
if (ft == null) {
continue;
}
FeatureValue.parseFeatureAsString(ft, probe);
float v1 = probe.getValueAsFloat();
String f1 = probe.getFeature();
map.put(f1, v1);
}
double d = 0.d;
for (String ft : ftvec2) {
if (ft == null) {
continue;
}
FeatureValue.parseFeatureAsString(ft, probe);
String f2 = probe.getFeature();
float v2f = probe.getValueAsFloat();
Float v1 = map.remove(f2);
if (v1 == null) {
d += Math.abs(v2f);
} else {
float v1f = v1.floatValue();
float diff = v1f - v2f;
d += Math.abs(diff);
}
}
for (Map.Entry<String, Float> e : map.entrySet()) {
float v1f = e.getValue();
d += Math.abs(v1f);
}
return d;
}
@Override
public String getDisplayString(String[] children) {
return "manhattan_distance(" + Arrays.toString(children) + ")";
}
}