content: /**
   * 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.bigtop.datagenerators.bigpetstore.generators.store;
  
  import java.util.List;
  
  import org.apache.bigtop.datagenerators.locations.Location;
  import org.apache.bigtop.datagenerators.samplers.pdfs.ProbabilityDensityFunction;
  
  public class StoreLocationIncomePDF implements ProbabilityDensityFunction<Location>
  {
  	double incomeNormalizationFactor;
  	double minIncome;
  	double k;
  
  	public StoreLocationIncomePDF(List<Location> zipcodeTable, double incomeScalingFactor)
  	{
  
  		double maxIncome = 0.0;
  		minIncome = Double.MAX_VALUE;
  
  		for(Location record : zipcodeTable)
  		{
  			maxIncome = Math.max(maxIncome, record.getMedianHouseholdIncome());
  			minIncome = Math.min(minIncome, record.getMedianHouseholdIncome());
  		}
  
  		k = Math.log(incomeScalingFactor) / (maxIncome - minIncome);
  
  		incomeNormalizationFactor = 0.0d;
  		for(Location record : zipcodeTable)
  		{
  			double weight = incomeWeight(record);
  			incomeNormalizationFactor += weight;
  		}
  	}
  
  	private double incomeWeight(Location record)
  	{
  		return Math.exp(k * (record.getMedianHouseholdIncome() - minIncome));
  	}
  
  
  	@Override
  	public double probability(Location datum)
  	{
  		double weight = incomeWeight(datum);
  
  		return weight / this.incomeNormalizationFactor;
  	}
  
  }
  