Utility
Class Tally

java.lang.Object
  |
  +--Utility.Tally

Direct Known Subclasses:

WeightedTally

public class Tally

extends java.lang.Object

Statistic Collection Objects
The Tally class is used for collecting simple statistics for a set of numbers. It provides functions to compute min, max, variance, standard deviation, sum, and sum of squares. All values are represented using doubles.
Note that the original source code for these classes was written by Zhonge Xiao in C++. The C++ code was ported over to Java and some minor design changes were made.

Field Summary

protected double	fCount Count of values in the tally.
protected java.util.Vector	fDataPoints
protected double	fMax Maximum value in the tally.
protected double	fMin Minimum value in the tally.
protected java.lang.String	fName The name of the tally.
protected double	fSum Sum of the values in the tally.
protected double	fSumSq Sum of the squares in the tally.
static java.lang.String	seperator Represents the string used for seperating consecutive numerical values.
static boolean	STORE_POINTS
static boolean	SUMMARY_ONLY
static boolean	WITH_HEADER
static boolean	WO_HEADER

Constructor Summary

Tally()
Initialize the object.

Tally(java.lang.String name, boolean storePoints)
Initialize the object, give the Tally a name.

Method Summary

double	average() Report the mean data point.
double	count() Report how many data points are in the tally.
boolean	isStoringPoints() Report whether or not this Tally object is storing the actual data points.
double	max() Report the maximum data point.
double	min() Report the minimum data point.
void	outputPoints(java.io.PrintStream out, boolean withHeader) Output all the data points stored in the Tally object.
void	outputSummary(java.io.PrintStream out, boolean withHeader) Output the summary statistics that were collected for the Tally.
void	reset() Remove all data points from the Tally.
double	stdDev() Report the standard deviation of the data points.
double	sum() Report the sum of the data points.
double	sumSq() Report the sum of the squares of the data points.
void	update(double x) Updates the statistics with the data item x.
void	updateBatch(Tally data) Update Tally with batch data.
double	variance() Report the variance of the data points.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

fCount

protected double fCount

Count of values in the tally.

fSum

protected double fSum

Sum of the values in the tally.

fSumSq

protected double fSumSq

Sum of the squares in the tally.

fMin

protected double fMin

Minimum value in the tally.

fMax

protected double fMax

Maximum value in the tally.

fName

protected java.lang.String fName

The name of the tally.

STORE_POINTS

public static final boolean STORE_POINTS

See Also:

Constant Field Values

SUMMARY_ONLY

public static final boolean SUMMARY_ONLY

See Also:

Constant Field Values

fDataPoints

protected java.util.Vector fDataPoints

WITH_HEADER

public static final boolean WITH_HEADER

See Also:

Constant Field Values

WO_HEADER

public static final boolean WO_HEADER

See Also:

Constant Field Values

seperator

public static java.lang.String seperator

Represents the string used for seperating consecutive numerical values. The user should feel free to change this to whatever he deems appropriate.

Constructor Detail

Tally

public Tally()

Initialize the object. With this constructor, no data points will be collected; only the summary statistics will be computed. Also, the tally will have no name.

Tally

public Tally(java.lang.String name,
             boolean storePoints)

Initialize the object, give the Tally a name.

Parameters:

name - The name of the Tally object. This will be used with the output functions.

storePoints - Whether or not the Tally should record all individiual data points. Tally.STORE_POINTS means the object should store data points, and Tally.SUMMARY_ONLY means the object should only compute summary statistics.

Method Detail

reset

public void reset()

Remove all data points from the Tally.

update

public void update(double x)

Updates the statistics with the data item x.

Parameters:

x - The value to record in the tally.

updateBatch

public void updateBatch(Tally data)

Update Tally with batch data.

Parameters:

data - The tally whose data will be added to this tally.

Throws:

java.lang.RuntimeException - A RuntimeException is thrown if the Tally object data is not storing data points but the current Tally object is. There is no problem however if we are not storing points but the data object is.

count

public double count()

Report how many data points are in the tally.

Returns:

The count of points in the tally.

sum

public double sum()

Report the sum of the data points.

Returns:

The sum of the values in the tally. If there are no values in the tally then 0 is returned.

sumSq

public double sumSq()

Report the sum of the squares of the data points.

Returns:

The sum of the squares of the values in the tally. If there are no values in the tally then 0 is returned.

min

public double min()

Report the minimum data point.

Returns:

The minimum value in the Tally. If there are no values in the tally then 0 is returned.

max

public double max()

Report the maximum data point.

Returns:

The maximum value in the Tally. If there are no values in the tally then 0 is returned.

average

public double average()

Report the mean data point.

Returns:

The average of the values in the tally. If there are no values in the tally then 0 is returned.

stdDev

public double stdDev()

Report the standard deviation of the data points.

Returns:

The standard deviation of the values in the tally. If there are fewer than 2 values in the tally then 0 is returned.

variance

public double variance()

Report the variance of the data points.

Returns:

The sample variance of the values in the tally. If there are fewer than 2 values in the tally then 0 is returned.

outputPoints

public void outputPoints(java.io.PrintStream out,
                         boolean withHeader)

Output all the data points stored in the Tally object.

Parameters:

out - The PrintStream to send the output to.

withHeader - true to print a header, false to skip the header. Tally.WITH_HEADER and Tally.WO_HEADER can be used instead of true and false.

Throws:

java.lang.RuntimeException - A RuntimeException is thrown if the Tally object is not currently storing data points.

outputSummary

public void outputSummary(java.io.PrintStream out,
                          boolean withHeader)

Output the summary statistics that were collected for the Tally.

Parameters:

out - The PrintStream to send the output to.

withHeader - true to print a header, false to skip the header. Tally.WITH_HEADER and Tally.WO_HEADER can be used instead of true and false.

isStoringPoints

public boolean isStoringPoints()

Report whether or not this Tally object is storing the actual data points.

Returns:

true if this Tally object is recording individual data points, false if it is only collecting summary statistics.