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DJUTILS statistical and data storage utilities
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package org.djutils.stats.summarizers;
import java.util.Calendar;
import org.djutils.exceptions.Throw;
/**
* The TimestampWeightedTally class defines a time-weighted tally based on timestamped data. The difference with a normal
* time-weighed tally is that the weight of a value is only known at the occurrence of the next timestamp. Furthermore, a last
* timestamp needs to be specified to determine the weight of the last value. Timestamps can be Number based or Calendar based.
*
* Copyright (c) 2020-2024 Delft University of Technology, Jaffalaan 5, 2628 BX Delft, the Netherlands. All rights reserved. See
* for project information https://simulation.tudelft.nl. The DSOL
* project is distributed under a three-clause BSD-style license, which can be found at
*
* https://simulation.tudelft.nl/dsol/3.0/license.html.
*
* @author Alexander Verbraeck
*/
public class TimestampWeightedTally extends WeightedTally
{
/** */
private static final long serialVersionUID = 20200228L;
/** startTime defines the time of the first observation. Often equals to 0.0, but can also have other value. */
private double startTime;
/** lastTimestamp stores the time of the last observation. Stored separately to avoid ulp rounding errors and allow ==. */
private double lastTimestamp;
/** lastValue tracks the last value. */
private double lastValue;
/** indicate whether the statistic is active or not (false before first event and after last event). */
private boolean active;
/**
* constructs a new TimestampWeightedTally with a description.
* @param description String; the description of this TimestampWeightedTally
*/
public TimestampWeightedTally(final String description)
{
super(description);
}
@Override
public void initialize()
{
synchronized (super.semaphore)
{
super.initialize();
this.startTime = Double.NaN;
this.lastTimestamp = Double.NaN;
this.lastValue = 0.0;
this.active = true;
}
}
/**
* Return whether the statistic is active (accepting observations) or not.
* @return boolean; whether the statistic is active (accepting observations) or not
*/
public boolean isActive()
{
return this.active;
}
/**
* End the observations and closes the last interval of observations. After ending, no more observations will be accepted.
* Calling this method will create an extra observation, and corresponding events for the EventBased implementations of this
* interface will be called.
* @param timestamp Number; the Number object representing the final timestamp
*/
public void endObservations(final Number timestamp)
{
register(timestamp, this.lastValue);
this.active = false;
}
/**
* End the observations and closes the last interval of observations. After ending, no more observations will be accepted.
* Calling this method will create an extra observation, and corresponding events for the EventBased implementations of this
* interface will be called.
* @param timestamp Calendar; the Calendar object representing the final timestamp
*/
public void endObservations(final Calendar timestamp)
{
register(timestamp, this.lastValue);
this.active = false;
}
/**
* Return the last observed value.
* @return double; the last observed value
*/
public double getLastValue()
{
return this.lastValue;
}
/**
* Process one observed Calender-based value. The time used will be the Calendar's time in milliseconds. Silently ignore
* when a value is registered, but tally is not active, i.e. when endObservations() has been called.
* @param timestamp Calendar; the Calendar object representing the timestamp
* @param value double; the value to process
* @return double; the value
* @throws NullPointerException when timestamp is null
* @throws IllegalArgumentException when value is NaN
* @throws IllegalArgumentException when given timestamp is before last timestamp
*/
public double register(final Calendar timestamp, final double value)
{
Throw.whenNull(timestamp, "timestamp object may not be null");
return registerValue(timestamp.getTimeInMillis(), value);
}
/**
* Process one observed Number-based value. Silently ignore when a value is registered, but tally is not active, i.e. when
* endObservations() has been called.
* @param timestamp Number; the object representing the timestamp
* @param value double; the value to process
* @return double; the value
* @throws NullPointerException when timestamp is null
* @throws IllegalArgumentException when value is NaN or timestamp is NaN
* @throws IllegalArgumentException when given timestamp is before last timestamp
*/
public double register(final Number timestamp, final double value)
{
return registerValue(timestamp, value);
}
/**
* Explicit;y override the double value method signature of WeightedTally to call the right method.
* Process one observed double value. Silently ignore when a value is registered, but tally is not active, i.e. when
* endObservations() has been called.
* @param timestamp Number; the object representing the timestamp
* @param value double; the value to process
* @return double; the value
* @throws NullPointerException when timestamp is null
* @throws IllegalArgumentException when value is NaN or timestamp is NaN
* @throws IllegalArgumentException when given timestamp is before last timestamp
*/
@Override
public double register(final double timestamp, final double value)
{
return registerValue(timestamp, value);
}
/**
* Process one observed Number-based value. Silently ignore when a value is registered, but tally is not active, i.e. when
* endObservations() has been called.
* @param timestamp Number; the object representing the timestamp
* @param value double; the value to process
* @return double; the value
* @throws NullPointerException when timestamp is null
* @throws IllegalArgumentException when value is NaN or timestamp is NaN
* @throws IllegalArgumentException when given timestamp is before last timestamp
*/
protected double registerValue(final Number timestamp, final double value)
{
Throw.whenNull(timestamp, "timestamp object may not be null");
Throw.when(Double.isNaN(value), IllegalArgumentException.class, "value may not be NaN");
double timestampDouble = timestamp.doubleValue();
Throw.when(Double.isNaN(timestampDouble), IllegalArgumentException.class, "timestamp may not be NaN");
Throw.when(timestampDouble < this.lastTimestamp, IllegalArgumentException.class,
"times not offered in ascending order. Last time was " + this.lastTimestamp + ", new timestamp was "
+ timestampDouble);
synchronized (super.semaphore)
{
// only calculate anything when the time interval is larger than 0, and when the TimestampWeightedTally is active
if ((Double.isNaN(this.lastTimestamp) || timestampDouble > this.lastTimestamp) && this.active)
{
if (Double.isNaN(this.startTime))
{
this.startTime = timestampDouble;
}
else
{
double deltaTime = Math.max(0.0, timestampDouble - this.lastTimestamp);
super.register(deltaTime, this.lastValue);
}
this.lastTimestamp = timestampDouble;
}
this.lastValue = value;
return value;
}
}
/**
* Return a string representing a header for a textual table with a monospaced font that can contain multiple statistics.
* @return String; header for the textual table.
*/
public static String reportHeader()
{
return "-".repeat(126)
+ String.format("%n| %-48.48s | %6.6s | %10.10s | %10.10s | %10.10s | %10.10s | %10.10s |%n",
"Timestamp-based weighted Tally name", "n", "interval", "w.mean", "w.st.dev", "min obs", "max obs")
+ "-".repeat(126);
}
@Override
public String reportLine()
{
return String.format("| %-48.48s | %6d | %s | %s | %s | %s | %s |", getDescription(), getN(),
formatFixed(this.lastTimestamp - this.startTime, 10), formatFixed(getWeightedPopulationMean(), 10),
formatFixed(getWeightedPopulationStDev(), 10), formatFixed(getMin(), 10), formatFixed(getMax(), 10));
}
/**
* Return a string representing a footer for a textual table with a monospaced font that can contain multiple statistics.
* @return String; footer for the textual table
*/
public static String reportFooter()
{
return "-".repeat(126);
}
@Override
public String toString()
{
return "TimestampWeightedTally" + super.toString().substring("WeightedTally".length());
}
}