MeasurementAggregator.java

package pl.llp.aircasting.view.presenter;

import pl.llp.aircasting.model.Measurement;

import com.google.common.collect.ImmutableList;

import java.util.ArrayList;
import java.util.Date;

import static com.google.common.collect.Lists.newArrayList;

public class MeasurementAggregator
{
  private double cumulativeLongitude;
  private double cumulativeLatitude;
  private double cumulativeValue;
  private long cumulativeTime;
  private int count;

  public void add(Measurement measurement)
  {
    cumulativeLongitude += measurement.getLongitude();
    cumulativeLatitude += measurement.getLatitude();
    cumulativeValue += measurement.getValue();
    cumulativeTime += measurement.getTime().getTime();
    count += 1;
  }

  public void reset()
  {
    cumulativeLongitude = cumulativeLatitude = cumulativeValue = cumulativeTime = count = 0;
  }

  public Measurement getAverage()
  {
    double latitude = cumulativeLatitude / count;
    double longitude = cumulativeLongitude / count;
    double value = cumulativeValue / count;
    Date time = new Date(cumulativeTime / count);
    return new Measurement(latitude, longitude, value, time);
  }

  public boolean isComposite()
  {
    return count > 1;
  }

  public boolean isEmpty()
  {
    return count == 0;
  }

  public ArrayList<Measurement> smoothenSamplesToReduceCount(ArrayList<Measurement> samples, int limit)
  {
    reset();

    ArrayList<Measurement> result = newArrayList();
    double fillFactor = 1.0 * limit / samples.size();
    double fill = 0.0;

    for (Measurement measurement : samples)
    {
      add(measurement);
      fill += fillFactor;
      if(fill > 1)
      {
        fill -= 1;
        result.add(getAverage());
        reset();
      }
    }
    if(count > 0)
    {
      result.add(getAverage());
    }
    return result;
  }

  public static Measurement getAverage(ImmutableList<Measurement> measurements)
  {
    MeasurementAggregator aggregator = new MeasurementAggregator();

    for (Measurement measurement : measurements)
    {
      aggregator.add(measurement);
    }

    return aggregator.getAverage();
  }
}