| /* |
| * 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 org.apache.datasketches.hive.kll; |
| |
| import org.apache.datasketches.hive.common.BytesWritableHelper; |
| import org.apache.datasketches.kll.KllFloatsSketch; |
| import org.apache.hadoop.hive.ql.exec.Description; |
| import org.apache.hadoop.hive.ql.exec.UDF; |
| import org.apache.hadoop.io.BytesWritable; |
| |
| @Description(name = "GetRank", value = "_FUNC_(sketch, value)", |
| extended = " Returns a normalized rank of a given value from a given KllFloatsSketch." |
| + " The returned rank is an approximation to the fraction of values of the distribution" |
| + " that are less than the given value (mass of the distribution below the given value).") |
| @SuppressWarnings("javadoc") |
| public class GetRankUDF extends UDF { |
| |
| /** |
| * Returns a normalized rank of a given value from a given sketch |
| * @param serializedSketch serialized sketch |
| * @param value the given value |
| * @return rank |
| */ |
| public Double evaluate(final BytesWritable serializedSketch, final float value) { |
| if (serializedSketch == null) { return null; } |
| final KllFloatsSketch sketch = KllFloatsSketch.heapify(BytesWritableHelper.wrapAsMemory(serializedSketch)); |
| return sketch.getRank(value); |
| } |
| |
| } |