myui commented on a change in pull request #192: [HIVEMALL-253]UDF map_roulette() created URL: https://github.com/apache/incubator-hivemall/pull/192#discussion_r279611120
########## File path: core/src/main/java/hivemall/tools/map/MapRouletteUDF.java ########## @@ -0,0 +1,192 @@ +/* + * 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.map; + +import hivemall.utils.hadoop.HiveUtils; +import org.apache.hadoop.hive.ql.exec.*; +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.MapObjectInspector; +import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector; +import org.apache.hadoop.hive.serde2.objectinspector.PrimitiveObjectInspector; +import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorUtils; +import java.util.*; +import static hivemall.HivemallConstants.*; + +/** + * The map_roulette() can be use to do roulette, according to each map.entry 's weight. + * + * @author Wang, Yizheng + */ +@Description(name = "map_roulette", value = "_FUNC_(Map<K, number> map)" + + " - Returns the key K which determine to its weight , the bigger weight is ,the more probability K will return. " + + "Number is a probability value or a positive weight") +@UDFType(deterministic = false) // it is false because it return value base on probability +public class MapRouletteUDF extends GenericUDF { + + /** + * The map passed in saved all the value and its weight + * + * @param m A map contains a lot of item as key, with their weight as value + * @return The key that computer selected according to key's weight + */ + private Object algorithm(Map<Object, Double> m) { + // normalize the weight + double sum = 0; + for (Map.Entry<Object, Double> entry : m.entrySet()) { + sum += entry.getValue(); + } + for (Map.Entry<Object, Double> entry : m.entrySet()) { + entry.setValue(entry.getValue() / sum); + } + + // sort and generate a number axis + List<Map.Entry<Object, Double>> entryList = new ArrayList<>(m.entrySet()); + Collections.sort(entryList, new MapRouletteUDF.KvComparator()); + double tmp = 0; + for (Map.Entry<Object, Double> entry : entryList) { + tmp += entry.getValue(); + entry.setValue(tmp); + } + + // judge last value + if (entryList.get(entryList.size() - 1).getValue() > 1.0) { + entryList.get(entryList.size() - 1).setValue(1.0); + } + + // pick a Object base on its weight + double cursor = Math.random(); + for (Map.Entry<Object, Double> entry : entryList) { + if (cursor < entry.getValue()) { + return entry.getKey(); + } + } + return null; + } + + private transient MapObjectInspector mapOI; + private transient PrimitiveObjectInspector valueOI; + + @Override + public ObjectInspector initialize(ObjectInspector[] arguments) throws UDFArgumentException { + if (arguments.length != 1) + throw new UDFArgumentLengthException( + "Expected one arguments for map_find_max_prob: " + arguments.length); + if (arguments[0].getCategory() != ObjectInspector.Category.MAP) { + throw new UDFArgumentTypeException(0, + "Only map type arguments are accepted for the key but " + arguments[0].getTypeName() + + " was passed as parameter 1."); + } + mapOI = HiveUtils.asMapOI(arguments[0]); + ObjectInspector keyOI = mapOI.getMapKeyObjectInspector(); + + //judge valueOI is a number + valueOI = (PrimitiveObjectInspector) mapOI.getMapValueObjectInspector(); + switch (valueOI.getTypeName()) { + case INT_TYPE_NAME: + case DOUBLE_TYPE_NAME: + case BIGINT_TYPE_NAME: + case FLOAT_TYPE_NAME: + case SMALLINT_TYPE_NAME: + case TINYINT_TYPE_NAME: + case DECIMAL_TYPE_NAME: + case STRING_TYPE_NAME: + // Pass an empty map or a map full of {null, null} will get string type + // An number in string format like "3.5" also support + break; + default: + throw new UDFArgumentException( + "Expected a number but get: " + valueOI.getTypeName()); + } + return keyOI; + } + + @Override + public Object evaluate(DeferredObject[] arguments) throws HiveException { + Map<Object, Double> input = processObjectDoubleMap(arguments[0]); + if (input == null) { + return null; + } + // handle empty map + if (input.isEmpty()) { + return null; + } + return algorithm(input); + } + + /** + * Process the data passed by user. + * + * @param argument data passed by user + * @return If all the value is , + * @throws HiveException If get the wrong weight value like {key = "Wang", value = "Zhang"}, + * "Zhang" isn't a number ,this Method will throw exception when + * convertPrimitiveToDouble("Zhang", valueOD) + */ + private Map<Object, Double> processObjectDoubleMap(DeferredObject argument) + throws HiveException { + // get + Map<?, ?> m = mapOI.getMap(argument.get()); + if (m == null) { + return null; + } + if (m.size() == 0) { + return null; + } + // convert + Map<Object, Double> input = new HashMap<>(); + Double avg = 0.0; + for (Map.Entry<?, ?> entry : m.entrySet()) { + Object key = entry.getKey(); + Double value = null; + if (entry.getValue() != null) { + value = PrimitiveObjectInspectorUtils.convertPrimitiveToDouble(entry.getValue(), + valueOI); + if (value < 0) { + throw new UDFArgumentException(entry.getValue() + " < 0"); + } + avg += value; + } + input.put(key, value); + } + avg /= m.size(); + for (Map.Entry<?, ?> entry : input.entrySet()) { + if (entry.getValue() == null) { + Object key = entry.getKey(); + input.put(key, avg); + } + } + return input; + } + + @Override + public String getDisplayString(String[] children) { + return "map_roulette(" + Arrays.toString(children) + ")"; + } + + private class KvComparator implements Comparator<Map.Entry<Object, Double>> { Review comment: This class should be static class. `private static class`. ---------------------------------------------------------------- This is an automated message from the Apache Git Service. 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