| /* |
| * 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.quantiles; |
| |
| import java.util.List; |
| |
| import org.apache.datasketches.memory.Memory; |
| import org.apache.datasketches.quantiles.DoublesSketch; |
| import org.apache.hadoop.hive.ql.exec.Description; |
| import org.apache.hadoop.hive.ql.exec.UDF; |
| import org.apache.hadoop.io.BytesWritable; |
| |
| @Description( |
| name = "GetQuantiles", |
| value = "_FUNC_(sketch, fractions...) or _FUNC_(sketch, number)", |
| extended = "Returns quantile values from a given DoublesSketch based on a given" |
| + " list of fractions or a number of evenly spaced fractions." |
| + " The fractions represent normalized ranks, and must be from 0 to 1 inclusive." |
| + " For example, a fraction of 0.5 corresponds to 50th percentile," |
| + " which is the median value of the distribution (the number separating the higher" |
| + " half of the probability distribution from the lower half)." |
| + " The number of evenly spaced fractions must be a positive integer greater than 0." |
| + " A value of 1 will return the min value (normalized rank of 0.0)." |
| + " A value of 2 will return the min and the max value (ranks 0.0 amd 1.0)." |
| + " A value of 3 will return the min, the median and the max value (ranks 0.0, 0.5, and 1.0), etc.") |
| @SuppressWarnings("javadoc") |
| public class GetQuantilesFromDoublesSketchUDF extends UDF { |
| |
| /** |
| * Returns a list of quantile values from a given sketch |
| * @param serializedSketch serialized sketch |
| * @param fractions list of values from 0 to 1 inclusive |
| * @return list of quantile values |
| */ |
| public List<Double> evaluate(final BytesWritable serializedSketch, final Double... fractions) { |
| if (serializedSketch == null) { return null; } |
| final DoublesSketch sketch = DoublesSketch.wrap(Memory.wrap(serializedSketch.getBytes())); |
| return Util.primitivesToList(sketch.getQuantiles(Util.objectsToPrimitives(fractions))); |
| } |
| |
| /** |
| * Returns a list of quantile values from a given sketch |
| * @param serializedSketch serialized sketch |
| * @param number of evenly spaced fractions |
| * @return list of quantile values |
| */ |
| public List<Double> evaluate(final BytesWritable serializedSketch, final int number) { |
| if (serializedSketch == null) { return null; } |
| final DoublesSketch sketch = DoublesSketch.wrap(Memory.wrap(serializedSketch.getBytes())); |
| final double[] quantiles = sketch.getQuantiles(number); |
| if (quantiles == null) { return null; } |
| return Util.primitivesToList(quantiles); |
| } |
| |
| } |