ql/src/java/org/apache/hadoop/hive/ql/udf/generic/GenericUDAFPercentileDisc.java

/*
 * 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.hadoop.hive.ql.udf.generic;

import java.util.List;
import java.util.Map;

import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.UDFArgumentTypeException;
import org.apache.hadoop.hive.ql.exec.WindowFunctionDescription;
import org.apache.hadoop.hive.ql.parse.SemanticException;
import org.apache.hadoop.hive.serde2.io.DoubleWritable;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.typeinfo.PrimitiveTypeInfo;
import org.apache.hadoop.hive.serde2.typeinfo.TypeInfo;
import org.apache.hadoop.io.LongWritable;

/**
 * GenericUDAFPercentileDisc.
 */
@Description(
        name = "dense_rank",
        value = "_FUNC_(input, pc) - "
                + "Returns the percentile of expr at pc (range: [0,1]) without interpolation.")
@WindowFunctionDescription(
        supportsWindow = false,
        pivotResult = true,
        supportsWithinGroup = true)
public class GenericUDAFPercentileDisc extends GenericUDAFPercentileCont {

  @Override
  public GenericUDAFEvaluator getEvaluator(TypeInfo[] parameters) throws SemanticException {
    validateParameterTypes(parameters);

    switch (((PrimitiveTypeInfo) parameters[0]).getPrimitiveCategory()) {
    case BYTE:
    case SHORT:
    case INT:
    case LONG:
    case VOID:
      return parameters[1].getCategory() == ObjectInspector.Category.LIST ?
              new PercentileDiscLongArrayEvaluator() : new PercentileDiscLongEvaluator();
    case FLOAT:
    case DOUBLE:
    case DECIMAL:
      return parameters[1].getCategory() == ObjectInspector.Category.LIST ?
              new PercentileDiscDoubleArrayEvaluator() : new PercentileDiscDoubleEvaluator();
    case STRING:
    case TIMESTAMP:
    case VARCHAR:
    case CHAR:
    case BOOLEAN:
    case DATE:
    default:
      throw new UDFArgumentTypeException(0,
          "Only numeric arguments are accepted but " + parameters[0].getTypeName() + " is passed.");
    }
  }

  /**
   * The evaluator for discrete percentile computation based on long.
   */
  public static class PercentileDiscLongEvaluator extends PercentileContLongEvaluator {
    public PercentileDiscLongEvaluator() {
    }

    @Override
    protected PercentileCalculator<LongWritable> getCalculator() {
      return new PercentileDiscLongCalculator();
    }
  }

  /**
   * The evaluator for discrete percentile computation based on array of longs.
   */
  public static class PercentileDiscLongArrayEvaluator extends PercentileContLongArrayEvaluator {
    public PercentileDiscLongArrayEvaluator() {
    }

    @Override
    protected PercentileCalculator<LongWritable> getCalculator() {
      return new PercentileDiscLongCalculator();
    }
  }

  /**
   * The evaluator for discrete percentile computation based on double.
   */
  public static class PercentileDiscDoubleEvaluator extends PercentileContDoubleEvaluator {
    public PercentileDiscDoubleEvaluator() {
      super();
    }

    @Override
    protected PercentileCalculator<DoubleWritable> getCalculator() {
      return new PercentileDiscDoubleCalculator();
    }
  }

  /**
   * The evaluator for discrete percentile computation based on array of doubles.
   */
  public static class PercentileDiscDoubleArrayEvaluator extends PercentileContDoubleArrayEvaluator {
    public PercentileDiscDoubleArrayEvaluator() {
      super();
    }

    @Override
    protected PercentileCalculator<DoubleWritable> getCalculator() {
      return new PercentileDiscDoubleCalculator();
    }
  }

  public static class PercentileDiscLongCalculator implements PercentileCalculator<LongWritable> {
    public double getPercentile(List<Map.Entry<LongWritable, LongWritable>> entriesList,
        double position) {
      long lower = (long) Math.floor(position);
      long higher = (long) Math.ceil(position);

      int i = 0;
      while (entriesList.get(i).getValue().get() < lower + 1) {
        i++;
      }

      long lowerKey = entriesList.get(i).getKey().get();
      if (higher == lower) {
        return lowerKey;
      }

      if (entriesList.get(i).getValue().get() < higher + 1) {
        i++;
      }
      return entriesList.get(i).getKey().get();
    }
  }

  public static class PercentileDiscDoubleCalculator
      implements PercentileCalculator<DoubleWritable> {
    public double getPercentile(List<Map.Entry<DoubleWritable, LongWritable>> entriesList,
        double position) {
      long lower = (long) Math.floor(position);
      long higher = (long) Math.ceil(position);

      int i = 0;
      while (entriesList.get(i).getValue().get() < lower + 1) {
        i++;
      }

      double lowerKey = entriesList.get(i).getKey().get();
      if (higher == lower) {
        return lowerKey;
      }

      if (entriesList.get(i).getValue().get() < higher + 1) {
        i++;
      }
      return entriesList.get(i).getKey().get();
    }
  }
}