SSJ
3.3.1
Stochastic Simulation in Java

The objects of this class are statistical probes or collectors, which are elementary devices for collecting statistics. More...
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 () 
Formats and returns a short, oneline report about this statistical probe. More...  
abstract String  shortReportHeader () 
Returns a string containing the name of the values returned in the report strings. More...  
boolean  isBroadcasting () 
Determines if this statistical probe is broadcasting observations to registered observers. More...  
void  setBroadcasting (boolean b) 
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...  
void  addObservationListener (ObservationListener l) 
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  broadcast = false 
boolean  showNobs = true 
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.
void addObservationListener  (  ObservationListener  l  ) 
Adds the observation listener l
to the list of observers of this statistical probe.
l  the new observation listener. 
NullPointerException  if l is null . 

abstract 
Returns the average for this collector.
This returns Double.NaN
if the probe was not updated since the last initialization.
String getName  (  ) 
Returns the name associated with this probe, or null
if no name was specified upon construction.
null
if not specified boolean isBroadcasting  (  ) 
Determines if this statistical probe is broadcasting observations to registered observers.
The default is false
.
boolean isCollecting  (  ) 
Determines if this statistical probe is collecting values.
The default is true
.
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.
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.
void notifyListeners  (  double  x  ) 
Notifies the observation x
to all registered observers if broadcasting is ON.
Otherwise, does nothing.
void removeObservationListener  (  ObservationListener  l  ) 
Removes the observation listener l
from the list of observers of this statistical probe.
l  the observation listener to be deleted. 

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 probespecific methods.

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

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.
globalName  the global name given to the formatted report. 
probes  the probes to include in the 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.
b  true to turn broadcasting ON, false to turn it OFF 
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.
b  true to activate statistical collection, false to deactivate it 

abstract 
Formats and returns a short, oneline report about this statistical probe.
This line is composed of whitespaceseparated fields which must correspond to the column names given by shortReportHeader(). This report should not contain any endofline 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 probespecific methods.

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.
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.