Documentation of 'umontreal.iro.lecuyer.stat.StatProbe' Java class
StatProbe
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umontreal.iro.lecuyer.stat

Class StatProbe

  • Direct Known Subclasses:
    Accumulate, Tally

    public abstract class StatProbe
extends java.lang.Object
    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 Accumulate (from package simevents) implement two kinds of probes, for the case of successive observations X1, X2, X3,..., 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.

    • Constructor Summary

      Constructors 
      Constructor and Description
      StatProbe() 

    • Method Summary

      All Methods Static Methods Instance Methods Abstract Methods Concrete Methods 
      Modifier and Type Method and Description
      void addObservationListener(ObservationListener l)
      Adds the observation listener l to the list of observers of this statistical probe.
      abstract double average()
      Returns the average for this collector.
      void clearObservationListeners()
      Removes all observation listeners from the list of observers of this statistical probe.
      StatProbe clone() 
      java.lang.String getName()
      Returns the name associated with this probe, or null if no name was specified upon construction.
      abstract void init()
      Initializes the statistical collector.
      boolean isBroadcasting()
      Determines if this statistical probe is broadcasting observations to registered observers.
      boolean isCollecting()
      Determines if this statistical probe is collecting values.
      double max()
      Returns the largest value taken by the variable since the last initialization of this probe.
      double min()
      Returns the smallest value taken by the variable since the last initialization of this probe.
      void notifyListeners(double x)
      Notifies the observation x to all registered observers if broadcasting is ON.
      void removeObservationListener(ObservationListener l)
      Removes the observation listener l from the list of observers of this statistical probe.
      abstract java.lang.String report()
      Returns a string containing a report for this statistical collector.
      static java.lang.String report(java.lang.String globalName, java.lang.Iterable<? extends StatProbe> probes)
      Equivalent to report, except that probes is an Iterable object instead of an array.
      static java.lang.String report(java.lang.String globalName, StatProbe[] probes)
      Formats short reports for each statistical probe in the array probes while aligning the probes' names.
      void setBroadcasting(boolean b)
      Instructs the probe to turn its broadcasting ON or OFF.
      void setCollecting(boolean b)
      Turns ON or OFF the collection of statistical observations.
      void setName(java.lang.String name)
      Sets the name of this statistical collector to name.
      abstract java.lang.String shortReport()
      Formats and returns a short, one-line report about this statistical probe.
      abstract java.lang.String shortReportHeader()
      Returns a string containing the name of the values returned in the report strings.
      double sum()
      Returns the sum cumulated so far for this probe.

      • Methods inherited from class java.lang.Object

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

    • Constructor Detail

      • StatProbe

        public StatProbe()

    • Method Detail

      • init

        public abstract void init()
        Initializes the statistical collector.

      • setName

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

      • getName

        public java.lang.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

      • min

        public 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

      • max

        public 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

      • sum

        public double sum()
        Returns the sum cumulated so far for this probe. The meaning of this sum depends on the subclass (e.g., Tally or Accumulate). This returns 0 if the probe was not updated since the last initialization.
        Returns:
        the sum for this probe

      • average

        public abstract double average()
        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

      • report

        public abstract java.lang.String report()
        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

      • shortReport

        public abstract java.lang.String shortReport()
        Formats and returns a short, one-line report about this statistical probe. 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.

      • shortReportHeader

        public abstract java.lang.String shortReportHeader()
        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.

      • report

        public static java.lang.String report(java.lang.String globalName,
                                      StatProbe[] probes)
        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 [tex2html_wrap_inline223] + 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

        public static java.lang.String report(java.lang.String globalName,
                                      java.lang.Iterable<? extends StatProbe> probes)
        Equivalent to report, 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.

      • isBroadcasting

        public boolean isBroadcasting()
        Determines if this statistical probe is broadcasting observations to registered observers. The default is false.
        Returns:
        the status of broadcasting.

      • setBroadcasting

        public 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

      • isCollecting

        public boolean isCollecting()
        Determines if this statistical probe is collecting values. The default is true.
        Returns:
        the status of statistical collecting.

      • setCollecting

        public 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

      • addObservationListener

        public void addObservationListener(ObservationListener l)
        Adds the observation listener l to the list of observers of this statistical probe.
        Parameters:
        l - the new observation listener.
        Throws:
        java.lang.NullPointerException - if l is null.

      • removeObservationListener

        public 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.

      • clearObservationListeners

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

      • notifyListeners

        public void notifyListeners(double x)
        Notifies the observation x to all registered observers if broadcasting is ON. Otherwise, does nothing.

      • clone

        public StatProbe clone()
                throws java.lang.CloneNotSupportedException
        Overrides:
        clone in class java.lang.Object
        Throws:
        java.lang.CloneNotSupportedException
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