math.statistics

Class AccumStat

java.lang.Object

org.trianacode.taskgraph.Unit

math.statistics.AccumStat

public class AccumStat
extends Unit

An AccumStat unit to calculate element-by-element statistical averages over the most recent input data sets, which may be of type GraphType or Const. The number of sets to accumulate (average) and the number of statistical measures to output are set in the parameter window. The unit works by accumulating the most recent input data sets (up to the desired number) and, at each time-step, outputting the given number of average moments of the accumulated input sets. The input sets may be real or complex, but they must be compatible with one another. Default values of the parameters are to output one statistic (the mean) averaged over the 10 most recent input sets.

The unit outputs simultaneously (from an appropriate number of output nodes) a collection of data sets of the same type as the input, one for each desired statistic (eg, mean, variance, etc.) The output sets contain the statistics of each of the dependent data arrays of the input sets that are of arithmetic type. The statistics are computed element-by-element, so that the output arrays have the same dimensionality and size as the input arrays. Dependent data that are not arithmetic arrays (numbers) are passed directly through to the output.

The unit can produce mean, variance, skewness (as the third moment, not normalized by the variance), kurtosis (again not normalized), and higher moments up to order 8. Data are output in the order of the moment: node 0 = mean, node 1 = variance, node 2 = skew, node 3 = kurtosis, etc. Apart from the mean, the formula for the nth moment is < (data - mean)^n >, where <..> indicates an average over the accumulated sets. Note that the moments are not normalized by the variance, as is the case for the usual definition of skew and kurtosis.

The accumulation continues in either single-step or continuous mode, as long as the network of units is not reset. At the beginning of a sequence, before the number of input sets reaches the number given in the parameter window, the output after each computation is a correct average of the sets so far received. After the number of inputs has reached the desired number, then the average is made over the appropriate number of the most recent input sets. If the number of moments is increased during the computation then the output for the extra moments will not be exactly correct until the desired number of inputs has been reached.

The algorithms saves a rolling queue of input data sets with a length equal to the number being averaged, so if input sets are large or the number to be averaged is large then the memory storage requirements can grow rapidly. Users should exercise caution.

If the number of data sets to accumulate is changed in the parameter window during a sequence of computations, the unit will behave correctly, either accumulating more (if it is increased) or forgetting the earliest ones (if it is decreased). If the number of moments to be output is reset in the parameter window to a number that is more than the current number of output nodes, then the number of nodes is automatically increased. If number of nodes is larger than the number of moments to be output, then the extra nodes are used to duplicate output data, just as for simple units that produce only one output. Data are output to the excess nodes in a cyclic manner: eg if there are 2 moments and 4 nodes the data will be output as node0:mean, node1:variance, node2:mean, node3:variance. If the network is reset then the accumulated data will be lost and the averaging will start anew.

Field Summary

Fields

Modifier and Type	Field and Description
int	highestPower The highest power to be computed (1 is for computing the mean).
int	oldHighestPower The highest power that was computed for the previous data set.

Fields inherited from class org.trianacode.taskgraph.Unit

CLONE_ALL_OUTPUT, CLONE_MULTIPLE_OUTPUT, COPY_OUTPUT, ESSENTIAL, ESSENTIAL_IF_CONNECTED, IMMEDIATE_UPDATE, INTERNAL, LATE_INITIALIZE, NO_UPDATE, ON_TASK_INSTANTATION, ON_USER_ACCESS, OPTIONAL, PROCESS_UPDATE, TRANSIENT, TRANSIENT_ACCESSIBLE, USER_ACCESSIBLE

Constructor Summary

Constructors

Constructor and Description
AccumStat()

Method Summary

Methods

Modifier and Type	Method and Description
java.lang.String	getHelpFile()
java.lang.String[]	getInputTypes() This method should return an array of the data types accepted by nodes not specified in getNodeInputTypes (e.g.
java.lang.String[]	getOutputTypes() This method should return an array of the data types output by nodes not specified in getNodeOutputTypes() (e.g.
java.lang.String	getPopUpDescription() This returns a brief! description of what the unit does.
void	init() Initialses information specific to AccumStat.
void	parameterUpdate(java.lang.String name, java.lang.Object value) Loads AccumStat's parameters from the parameter file.
void	process() The main functionality of AccumStat goes here
void	reset() Resets AccumStat
void	stopping() Called when the stop button is pressed within the MainTriana Window

Methods inherited from class org.trianacode.taskgraph.Unit

debug, debug, defineParameter, dispose, extractClipInState, getClipIn, getClipIn, getControlInterface, getDefaultInputNodes, getDefaultNodeRequirement, getDefaultOutputNodes, getDisplayName, getDisplayPackage, getGUIBuilderV2Info, getHelpFileLocation, getInputAtNode, getInputNodeCount, getMaximumInputNodes, getMaximumOutputNodes, getMinimumInputNodes, getMinimumOutputNodes, getNodeInputTypes, getNodeOutputTypes, getOutputNodeCount, getOutputPolicy, getPackageName, getParameter, getParameterPanelClass, getParameterPanelInstantiate, getParameterType, getParameterUpdatePolicy, getRunnableInterface, getTask, getTaskGraphContext, getToolName, getToolPackage, getToolTable, getVersion, hideParameterPanel, isClipInName, isInputAtNode, isOutputSent, isParameter, log, log, notifyError, notifyError, output, outputAtNode, outputAtNode, parameterUpdated, putClipIn, removeClipIn, removeParameter, restoreClipInState, setDefaultInputNodes, setDefaultNodeRequirement, setDefaultOutputNodes, setDisplayName, setDisplayPackage, setGUIBuilderV2Info, setHelpFileLocation, setMaximumInputNodes, setMaximumOutputNodes, setMinimumInputNodes, setMinimumOutputNodes, setOutputPolicy, setParameter, setParameterPanelClass, setParameterPanelInstantiate, setParameterUpdatePolicy, setPopUpDescription, setRunnableInterface, setToolName, setToolPackage, setVersion, showParameterPanel

Methods inherited from class java.lang.Object

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

Field Detail

highestPower

public int highestPower

The highest power to be computed (1 is for computing the mean). This is set when the user chooses the number of output nodes. It must be less than or equal to momentLimit.

oldHighestPower

public int oldHighestPower

The highest power that was computed for the previous data set. It must be less than or equal to momentLimit.

Constructor Detail

AccumStat

public AccumStat()

Method Detail

getPopUpDescription

public java.lang.String getPopUpDescription()

This returns a brief! description of what the unit does. The text here is shown in a pop up window when the user puts the mouse over the unit icon for more than a second.

Overrides:

getPopUpDescription in class Unit

init

public void init()

Initialses information specific to AccumStat.

Overrides:

init in class Unit

reset

public void reset()

Resets AccumStat

Overrides:

reset in class Unit

parameterUpdate

public void parameterUpdate(java.lang.String name,
                   java.lang.Object value)

Loads AccumStat's parameters from the parameter file.

Overrides:

parameterUpdate in class Unit

getInputTypes

public java.lang.String[] getInputTypes()

Description copied from class: Unit

This method should return an array of the data types accepted by nodes not specified in getNodeInputTypes (e.g. triana.types.VectorType). If no package is specified then triana.types is assumed.

Specified by:

getInputTypes in class Unit

Returns:

a string containing the names of the types allowed to be input to AccumStat, each separated by a white space.

getOutputTypes

public java.lang.String[] getOutputTypes()

Description copied from class: Unit

This method should return an array of the data types output by nodes not specified in getNodeOutputTypes() (e.g. triana.types.VectorType). If no package is specified then triana.types is assumed.

Specified by:

getOutputTypes in class Unit

Returns:

an array of the output types for this unit

getHelpFile

public java.lang.String getHelpFile()

stopping

public void stopping()

Called when the stop button is pressed within the MainTriana Window

Overrides:

stopping in class Unit

process

public void process()

The main functionality of AccumStat goes here

Specified by:

process in class Unit