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* Licensed to the Apache Software Foundation (ASF) under one
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* 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
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package hivemall.ftvec.selection;
import hivemall.utils.hadoop.HiveUtils;
import hivemall.utils.hadoop.WritableUtils;
import hivemall.utils.lang.Preconditions;
import hivemall.utils.math.StatsUtils;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
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.exec.UDFArgumentLengthException;
import org.apache.hadoop.hive.ql.exec.UDFArgumentTypeException;
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.io.DoubleWritable;
import org.apache.hadoop.hive.serde2.objectinspector.ListObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.objectinspector.PrimitiveObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
@Description(name = "chi2",
value = "_FUNC_(array<array<number>> observed, array<array<number>> expected)"
+ " - Returns chi2_val and p_val of each columns as <array<double>, array<double>>")
@UDFType(deterministic = true, stateful = false)
public final class ChiSquareUDF extends GenericUDF {
private ListObjectInspector observedOI;
private ListObjectInspector observedRowOI;
private PrimitiveObjectInspector observedElOI;
private ListObjectInspector expectedOI;
private ListObjectInspector expectedRowOI;
private PrimitiveObjectInspector expectedElOI;
private int nFeatures = -1;
private double[] observedRow = null; // to reuse
private double[] expectedRow = null; // to reuse
private double[][] observed = null; // shape = (#features, #classes)
private double[][] expected = null; // shape = (#features, #classes)
private List<DoubleWritable>[] result;
@SuppressWarnings("unchecked")
@Override
public ObjectInspector initialize(ObjectInspector[] OIs) throws UDFArgumentException {
if (OIs.length != 2) {
throw new UDFArgumentLengthException("Specify two arguments: " + OIs.length);
}
if (!HiveUtils.isNumberListListOI(OIs[0])) {
throw new UDFArgumentTypeException(0,
"Only array<array<number>> type argument is acceptable but " + OIs[0].getTypeName()
+ " was passed as `observed`");
}
if (!HiveUtils.isNumberListListOI(OIs[1])) {
throw new UDFArgumentTypeException(1,
"Only array<array<number>> type argument is acceptable but " + OIs[1].getTypeName()
+ " was passed as `expected`");
}
this.observedOI = HiveUtils.asListOI(OIs[1]);
this.observedRowOI = HiveUtils.asListOI(observedOI.getListElementObjectInspector());
this.observedElOI = HiveUtils.asDoubleCompatibleOI(observedRowOI.getListElementObjectInspector());
this.expectedOI = HiveUtils.asListOI(OIs[0]);
this.expectedRowOI = HiveUtils.asListOI(expectedOI.getListElementObjectInspector());
this.expectedElOI = HiveUtils.asDoubleCompatibleOI(expectedRowOI.getListElementObjectInspector());
this.result = new List[2];
List<ObjectInspector> fieldOIs = new ArrayList<ObjectInspector>();
fieldOIs.add(ObjectInspectorFactory.getStandardListObjectInspector(PrimitiveObjectInspectorFactory.writableDoubleObjectInspector));
fieldOIs.add(ObjectInspectorFactory.getStandardListObjectInspector(PrimitiveObjectInspectorFactory.writableDoubleObjectInspector));
return ObjectInspectorFactory.getStandardStructObjectInspector(
Arrays.asList("chi2", "pvalue"), fieldOIs);
}
@Override
public List<DoubleWritable>[] evaluate(DeferredObject[] dObj) throws HiveException {
List<?> observedObj = observedOI.getList(dObj[0].get()); // shape = (#classes, #features)
List<?> expectedObj = expectedOI.getList(dObj[1].get()); // shape = (#classes, #features)
if (observedObj == null || expectedObj == null) {
return null;
}
final int nClasses = observedObj.size();
Preconditions.checkArgument(nClasses == expectedObj.size(), UDFArgumentException.class);
// explode and transpose matrix
for (int i = 0; i < nClasses; i++) {
Object observedObjRow = observedObj.get(i);
Object expectedObjRow = expectedObj.get(i);
Preconditions.checkNotNull(observedObjRow, UDFArgumentException.class);
Preconditions.checkNotNull(expectedObjRow, UDFArgumentException.class);
if (observedRow == null) {
observedRow = HiveUtils.asDoubleArray(observedObjRow, observedRowOI, observedElOI,
false);
expectedRow = HiveUtils.asDoubleArray(expectedObjRow, expectedRowOI, expectedElOI,
false);
nFeatures = observedRow.length;
observed = new double[nFeatures][nClasses];
expected = new double[nFeatures][nClasses];
} else {
HiveUtils.toDoubleArray(observedObjRow, observedRowOI, observedElOI, observedRow,
false);
HiveUtils.toDoubleArray(expectedObjRow, expectedRowOI, expectedElOI, expectedRow,
false);
}
for (int j = 0; j < nFeatures; j++) {
observed[j][i] = observedRow[j];
expected[j][i] = expectedRow[j];
}
}
Map.Entry<double[], double[]> chi2 = StatsUtils.chiSquare(observed, expected);
result[0] = WritableUtils.toWritableList(chi2.getKey(), result[0]);
result[1] = WritableUtils.toWritableList(chi2.getValue(), result[1]);
return result;
}
@Override
public void close() throws IOException {
// help GC
this.observedRow = null;
this.expectedRow = null;
this.observed = null;
this.expected = null;
this.result = null;
}
@Override
public String getDisplayString(String[] children) {
final StringBuilder sb = new StringBuilder();
sb.append("chi2");
sb.append("(");
if (children.length > 0) {
sb.append(children[0]);
for (int i = 1; i < children.length; i++) {
sb.append(", ");
sb.append(children[i]);
}
}
sb.append(")");
return sb.toString();
}
}