Android Open Source - interdroid-swan Timestamped Value

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License

The source code is released under:
Copyright (c) 2008-2011 Vrije Universiteit, The Netherlands All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the follo...
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Java Source Code

package interdroid.swan.swansong;
//  w  w w  .jav a2  s  .  co  m
import java.io.Serializable;
import java.util.Collections;
import java.util.List;

import android.os.Parcel;
import android.os.Parcelable;

/**
 * A tuple containing a value, a timestamp. Also includes static methods for
 * some calculations on lists of TimestampedValues
 * 
 * @author roelof &lt;rkemp@cs.vu.nl&gt;
 * @author nick &lt;palmer@cs.vu.nl&gt;
 */
public class TimestampedValue implements Serializable, Parcelable,
    Comparable<TimestampedValue> {

  /**
   *
   */
  private static final long serialVersionUID = -1758020216184616414L;

  /** The value. */
  private Object mValue;

  /** The timestamp. */
  private long mTimestamp;

  /**
   * Construct from a parcel.
   * 
   * @param saved
   *            read from a parcel
   */
  private TimestampedValue(final Parcel saved) {
    readFromParcel(saved);
  }

  /**
   * Instantiates a new timestamped value.
   * 
   * @param value
   *            the value
   */
  public TimestampedValue(final Object value) {
    this(value, System.currentTimeMillis());
  }

  /**
   * Instantiates a new timestamped value.
   * 
   * @param value
   *            the value
   * @param timestamp
   *            the timestamp
   */
  public TimestampedValue(final Object value, final long timestamp) {
    this.mValue = value;
    this.mTimestamp = timestamp;
  }

  /**
   * @return the value
   */
  public final Object getValue() {
    return mValue;
  }

  /**
   * @return the timestamp
   */
  public final long getTimestamp() {
    return mTimestamp;
  }

  /*
   * (non-Javadoc)
   * 
   * @see java.lang.Object#toString()
   */
  @Override
  public final String toString() {
    return "" + mValue + " (timestamp: " + mTimestamp + ")";
  }

  /**
   * Applies the reduction mode to the values.
   * 
   * @param values
   *            the value to reduce
   * @return the reduced values.
   */
  public static TimestampedValue[] applyMode(
      final List<TimestampedValue> values, HistoryReductionMode mode) {
    switch (mode) {
    case MAX:
      return new TimestampedValue[] { TimestampedValue
          .findMaxValue(values) };
    case MIN:
      return new TimestampedValue[] { TimestampedValue
          .findMinValue(values) };
    case MEAN:
      return new TimestampedValue[] { TimestampedValue
          .calculateMean(values) };
    case MEDIAN:
      return new TimestampedValue[] { TimestampedValue
          .calculateMedian(values) };
    case ALL:
    case ANY:
    default:
      return values.toArray(new TimestampedValue[values.size()]);
    }
  }

  /**
   * Calculate mean over array of values.
   * 
   * @param values
   *            an array of timestamped values (double or castable to double)
   * 
   * @return the mean value, with the oldest timestamp of all values (it will
   *         be invalid when this timestamp is no longer in the history
   *         window)
   */
  public static TimestampedValue calculateMean(
      final List<TimestampedValue> values) {
    double sumValues = 0.0;

    for (TimestampedValue value : values) {
      sumValues += (Double) value.mValue;
    }
    return new TimestampedValue(sumValues / values.size(),
        values.get(0).mTimestamp);
  }

  /**
   * Calculate a time weighted mean over array of values.
   * 
   * @param values
   *            an array of timestamped values (double or castable to double)
   * 
   * @return the time weighted mean value, with the oldest timestamp of all
   *         values (it will be invalid when this timestamp is no longer in
   *         the history window)
   */
  public static TimestampedValue calculateTimeWeightedMean(
      final TimestampedValue[] values) {
    throw new RuntimeException("Not implemented");
  }

  /**
   * @param values
   *            the values to search for the median in
   * @return the median value, with the oldest timestamp of all values (it
   *         will be invalid when this timestamp is no longer in the history
   *         window)
   */
  public static final TimestampedValue calculateMedian(
      final List<TimestampedValue> values) {
    long timestamp = values.get(0).getTimestamp();
    Collections.sort(values);
    TimestampedValue result = values.get(values.size() / 2);
    result.mTimestamp = timestamp;
    return result;
  }

  /**
   * Find maximum value.
   * 
   * @param values
   *            an array of timestamped values
   * 
   * @return the timestamped maximum value
   */
  @SuppressWarnings({ "unchecked", "rawtypes" })
  public static TimestampedValue findMaxValue(
      final List<TimestampedValue> values) {
    TimestampedValue maxValue = null;
    for (TimestampedValue value : values) {
      if (maxValue == null) {
        maxValue = value;
      } else if (((Comparable) maxValue.mValue).compareTo(value.mValue) < 0) {
        maxValue = value;
      }
    }
    return maxValue;
  }

  /**
   * Find mininimum value.
   * 
   * @param values
   *            an array of timestamped values
   * 
   * @return the timestamped minimum value
   */
  @SuppressWarnings({ "unchecked", "rawtypes" })
  public static TimestampedValue findMinValue(
      final List<TimestampedValue> values) {
    TimestampedValue minValue = null;
    for (TimestampedValue value : values) {
      if (minValue == null) {
        minValue = value;
      } else if (((Comparable) minValue.mValue).compareTo(value.mValue) > 0) {
        minValue = value;
      }
    }
    return minValue;
  }

  @Override
  public final int describeContents() {
    return 0;
  }

  @Override
  public final void writeToParcel(final Parcel dest, final int flags) {
    dest.writeLong(mTimestamp);
    dest.writeValue(mValue);
  }

  /**
   * Read from parcel.
   * 
   * @param in
   *            the in
   */
  private void readFromParcel(final Parcel in) {
    mTimestamp = in.readLong();
    mValue = in.readValue(this.getClass().getClassLoader());
  }

  /** The CREATOR. */
  public static final TimestampedValue.Creator<TimestampedValue> CREATOR = new TimestampedValue.Creator<TimestampedValue>() {

    @Override
    public TimestampedValue createFromParcel(final Parcel source) {
      return new TimestampedValue(source);
    }

    @Override
    public TimestampedValue[] newArray(final int size) {
      return new TimestampedValue[size];
    }
  };

  @SuppressWarnings({ "rawtypes", "unchecked" })
  @Override
  public final int compareTo(final TimestampedValue another) {
    return ((Comparable) mValue)
        .compareTo(((TimestampedValue) another).mValue);
  }

  @SuppressWarnings({ "rawtypes", "unchecked" })
  @Override
  public boolean equals(Object o) {
    if (o == null) {
      return false;
    }
    if (o instanceof TimestampedValue) {
      if (mTimestamp != ((TimestampedValue) o).mTimestamp) {
        return false;
      }
      if (mValue instanceof Comparable<?>
          && ((TimestampedValue) o).mValue instanceof Comparable<?>) {
        if (((Comparable) mValue)
            .compareTo((Comparable) ((TimestampedValue) o).mValue) == 0) {
          return true;
        }
      }
    }
    return super.equals(o);
  }

}
Java Source Code List
