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ArrayFlattenUDF.java
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ArrayFlattenUDF.java
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/*
* 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.tools.array;
import hivemall.utils.hadoop.HiveUtils;
import java.util.ArrayList;
import java.util.List;
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.ObjectInspector.Category;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorUtils;
@Description(name = "array_flatten",
value = "_FUNC_(array<array<ANY>>) - Returns an array with the elements flattened.")
@UDFType(deterministic = true, stateful = false)
public final class ArrayFlattenUDF extends GenericUDF {
private ListObjectInspector listOI;
private ListObjectInspector nextedListOI;
private ObjectInspector elemOI;
private final List<Object> result = new ArrayList<>();
@Override
public ObjectInspector initialize(ObjectInspector[] argOIs) throws UDFArgumentException {
if (argOIs.length != 1) {
throw new UDFArgumentException(
"array_flatten expects exactly one argument: " + argOIs.length);
}
this.listOI = HiveUtils.asListOI(argOIs[0]);
ObjectInspector listElemOI = listOI.getListElementObjectInspector();
if (listElemOI.getCategory() != Category.LIST) {
throw new UDFArgumentException(
"array_flatten takes array of array for the argument: " + listOI.toString());
}
this.nextedListOI = HiveUtils.asListOI(listElemOI);
this.elemOI = nextedListOI.getListElementObjectInspector();
return ObjectInspectorFactory.getStandardListObjectInspector(
ObjectInspectorUtils.getStandardObjectInspector(elemOI));
}
@Override
public List<Object> evaluate(DeferredObject[] args) throws HiveException {
result.clear();
Object arg0 = args[0].get();
if (arg0 == null) {
return null;
}
final int listLength = listOI.getListLength(arg0);
for (int i = 0; i < listLength; i++) {
final Object subarray = listOI.getListElement(arg0, i);
if (subarray == null) {
continue;
}
final int subarrayLength = nextedListOI.getListLength(subarray);
for (int j = 0; j < subarrayLength; j++) {
Object elem = nextedListOI.getListElement(subarray, j);
if (elem == null) {
continue;
}
result.add(elem);
}
}
return result;
}
@Override
public String getDisplayString(String[] args) {
final StringBuffer buf = new StringBuffer();
buf.append("array_flatten(");
for (int i = 0, len = args.length; i < len; i++) {
if (i != 0) {
buf.append(", ");
}
buf.append(args[i]);
}
buf.append(")");
return buf.toString();
}
}