| /* |
| * 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 hivemall.utils.lang.StringUtils; |
| |
| 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.ObjectInspectorUtils; |
| import org.apache.hadoop.hive.serde2.objectinspector.PrimitiveObjectInspector; |
| import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory; |
| import org.apache.hadoop.io.IntWritable; |
| |
| @Description(name = "argmax", |
| value = "_FUNC_(array<T> a) - Returns the first index of the maximum value", |
| extended = "SELECT argmax(array(5,2,0,1));\n" + "> 0") |
| @UDFType(deterministic = true, stateful = false) |
| public final class ArgmaxUDF extends GenericUDF { |
| |
| private ListObjectInspector listOI; |
| private PrimitiveObjectInspector elemOI; |
| |
| private IntWritable result; |
| |
| @Override |
| public ObjectInspector initialize(ObjectInspector[] argOIs) throws UDFArgumentException { |
| if (argOIs.length != 1) { |
| throw new UDFArgumentException("argmax takes exactly one argument: " + argOIs.length); |
| } |
| this.listOI = HiveUtils.asListOI(argOIs[0]); |
| this.elemOI = HiveUtils.asPrimitiveObjectInspector(listOI.getListElementObjectInspector()); |
| |
| this.result = new IntWritable(); |
| |
| return PrimitiveObjectInspectorFactory.writableIntObjectInspector; |
| } |
| |
| @Override |
| public IntWritable evaluate(DeferredObject[] arguments) throws HiveException { |
| Object arg0 = arguments[0].get(); |
| if (arg0 == null) { |
| return null; |
| } |
| |
| int index = -1; |
| Object maxObject = null; |
| final int size = listOI.getListLength(arg0); |
| for (int i = 0; i < size; i++) { |
| Object ai = listOI.getListElement(arg0, i); |
| if (ai == null) { |
| continue; |
| } |
| |
| if (maxObject == null) { |
| maxObject = ai; |
| index = i; |
| } else { |
| final int cmp = ObjectInspectorUtils.compare(ai, elemOI, maxObject, elemOI); |
| if (cmp > 0) { |
| maxObject = ai; |
| index = i; |
| } |
| } |
| } |
| |
| result.set(index); |
| return result; |
| } |
| |
| @Override |
| public String getDisplayString(String[] children) { |
| return "argmax(" + StringUtils.join(children, ',') + ')'; |
| } |
| |
| } |