SSJ  3.3.1 Stochastic Simulation in Java
StatProbe Class Referenceabstract

The objects of this class are statistical probes or collectors, which are elementary devices for collecting statistics. More...

Inheritance diagram for StatProbe:
[legend]

## Public Member Functions

abstract void init ()
Initializes the statistical collector.

void setName (String name)
Sets the name of this statistical collector to name.

String getName ()
Returns the name associated with this probe, or null if no name was specified upon construction. More...

double min ()
Returns the smallest value taken by the variable since the last initialization of this probe. More...

double max ()
Returns the largest value taken by the variable since the last initialization of this probe. More...

double sum ()
Returns the sum cumulated so far for this probe. More...

abstract double average ()
Returns the average for this collector. More...

abstract String report ()
Returns a string containing a report for this statistical collector. More...

abstract String shortReport ()

Returns a string containing the name of the values returned in the report strings. More...

Determines if this statistical probe is broadcasting observations to registered observers. More...

Instructs the probe to turn its broadcasting ON or OFF. More...

boolean isCollecting ()
Determines if this statistical probe is collecting values. More...

void setCollecting (boolean b)
Turns ON or OFF the collection of statistical observations. More...

Adds the observation listener l to the list of observers of this statistical probe. More...

void removeObservationListener (ObservationListener l)
Removes the observation listener l from the list of observers of this statistical probe. More...

void clearObservationListeners ()
Removes all observation listeners from the list of observers of this statistical probe.

void notifyListeners (double x)
Notifies the observation x to all registered observers if broadcasting is ON. More...

StatProbe clone () throws CloneNotSupportedException

## Static Public Member Functions

static String report (String globalName, StatProbe[] probes)
Formats short reports for each statistical probe in the array probes while aligning the probes’ names. More...

static String report (String globalName, Iterable<? extends StatProbe > probes)
Equivalent to #report(String,StatProbe[]), except that probes is an Iterable object instead of an array. More...

## Protected Attributes

String name

double maxValue

double minValue

double sumValue

boolean collect = true

boolean showNobs = true

## Detailed Description

The objects of this class are statistical probes or collectors, which are elementary devices for collecting statistics.

Each probe collects statistics on a given variable. The subclasses Tally, TallyStore, and umontreal.ssj.simevents.Accumulate (from package umontreal.ssj.simevents ) implement two kinds of probes, for the case of successive observations $$X_1,X_2,X_3,…$$, and for the case of a variable whose value evolves in time, respectively.

Each instance of StatProbe contains a list of ObservationListener that can listen to individual observations. When a probe is updated, i.e., receives a new statistical observation, it broadcasts this new data to all registered observers. The broadcasting of observations to registered observers can be turned ON or OFF at any time. It is initially OFF by default and should stay OFF when there are no registered observers, to avoid unnecessary overhead.

The data collection by the statistical probe itself can also be turned ON or OFF. By default, it is initially ON. We can turn it OFF, for example, if we want to use the statistical probe only to pass data to the observers, and do not need it to store any information.

In the simplest programs, collection is ON, broadcast is OFF, and the overall stats are accessed via the methods min, max, sum, average, ... of the collector.

## Member Function Documentation

 void addObservationListener ( ObservationListener l )

Adds the observation listener l to the list of observers of this statistical probe.

Parameters
 l the new observation listener.
Exceptions
 NullPointerException if l is null.

## ◆ average()

 abstract double average ( )
abstract

Returns the average for this collector.

This returns Double.NaN if the probe was not updated since the last initialization.

Returns
the average value of the collected observations

## ◆ getName()

 String getName ( )

Returns the name associated with this probe, or null if no name was specified upon construction.

Returns
the name associated to this collector, or null if not specified

Determines if this statistical probe is broadcasting observations to registered observers.

The default is false.

Returns

## ◆ isCollecting()

 boolean isCollecting ( )

Determines if this statistical probe is collecting values.

The default is true.

Returns
the status of statistical collecting.

## ◆ max()

 double max ( )

Returns the largest value taken by the variable since the last initialization of this probe.

This returns Double.NEGATIVE_INFINITY if the probe was not updated since the last initialization.

Returns
the largest value taken by the collector since last initialization

## ◆ min()

 double min ( )

Returns the smallest value taken by the variable since the last initialization of this probe.

This returns Double.POSITIVE_INFINITY if the probe was not updated since the last initialization.

Returns
the smallest value taken by the collector since last initialization

## ◆ notifyListeners()

 void notifyListeners ( double x )

Notifies the observation x to all registered observers if broadcasting is ON.

Otherwise, does nothing.

## ◆ removeObservationListener()

 void removeObservationListener ( ObservationListener l )

Removes the observation listener l from the list of observers of this statistical probe.

Parameters
 l the observation listener to be deleted.

## ◆ report() [1/3]

 abstract String report ( )
abstract

Returns a string containing a report for this statistical collector.

The contents of this report depends on the statistical probe as well as on the parameters set by the user through probe-specific methods.

Returns
a report for this probe, represented as a string

## ◆ report() [2/3]

 static String report ( String globalName, StatProbe [] probes )
static

Formats short reports for each statistical probe in the array probes while aligning the probes’ names.

This method first formats the given global name. It then determines the maximum length $$\ell$$ of the names of probes in the given array. The first line of the report is composed of $$\ell+3$$ spaces followed by the string returned by shortReportHeader called on the first probe in probes. Each remaining line corresponds to a statistical probe; it contains the probe’s name followed by the contents returned by shortReport. Note that this method assumes that probes contains no null element.

Parameters
 globalName the global name given to the formatted report. probes the probes to include in the report.
Returns
the formatted report.

## ◆ report() [3/3]

 static String report ( String globalName, Iterable probes )
static

Equivalent to #report(String,StatProbe[]), except that probes is an Iterable object instead of an array.

Of course, the iterator returned by probes should enumerate the statistical probes to include in the report in a consistent and sensible order.

Parameters
 globalName the global name given to the formatted report. probes the probes to include in the report.
Returns
the formatted report.

 void setBroadcasting ( boolean b )

Instructs the probe to turn its broadcasting ON or OFF.

The default value is OFF. Warning: To avoid useless overhead and performance degradation, broadcasting should never be turned ON when there are no registered observers.

Parameters
 b true to turn broadcasting ON, false to turn it OFF

## ◆ setCollecting()

 void setCollecting ( boolean b )

Turns ON or OFF the collection of statistical observations.

The default value is ON. When statistical collection is turned OFF, observations added to the probe are passed to the registered observers if broadcasting is turned ON, but are not counted as observations by the probe itself.

Parameters
 b true to activate statistical collection, false to deactivate it

## ◆ shortReport()

 abstract String shortReport ( )
abstract

This line is composed of whitespace-separated fields which must correspond to the column names given by shortReportHeader(). This report should not contain any end-of-line character, and does not include the name of the probe. Its contents depends on the statistical probe as well as on the parameters set by the user through probe-specific methods.

Returns
the short report for the probe.

abstract

Returns a string containing the name of the values returned in the report strings.

The returned string must depend on the type of probe and on the reporting options only. It must not depend on the observations received by the probe. This can be used as header when printing several reports. For example, 

         System.out.println (probe1.shortReportHeader());
System.out.println (probe1.getName() + " " + probe1.shortReport());
System.out.println (probe2.getName() + " " + probe2.shortReport());
...


  Alternatively, one can use report(String,StatProbe[]) to get a report with aligned probe names.

Returns
the header string for the short reports.

## ◆ sum()

 double sum ( )

Returns the sum cumulated so far for this probe.

The meaning of this sum depends on the subclass (e.g., Tally or umontreal.ssj.simevents.Accumulate ). This returns 0 if the probe was not updated since the last initialization.

Returns
the sum for this probe

The documentation for this class was generated from the following file:
• StatProbe.java