org.pentaho.di.trans.steps.reservoirsampling

Class ReservoirSamplingData

java.lang.Object

org.pentaho.di.trans.step.BaseStepData

org.pentaho.di.trans.steps.reservoirsampling.ReservoirSamplingData

All Implemented Interfaces:

StepDataInterface

public class ReservoirSamplingData
extends BaseStepData
implements StepDataInterface

Holds temporary data (i.e. sampled rows). Implements the reservoir sampling algorithm "R" by Jeffrey Scott Vitter.

For more information see:

Vitter, J. S. Random Sampling with a Reservoir. ACM Transactions on Mathematical Software, Vol. 11, No. 1, March 1985. Pages 37-57.

Version:

1.0

Author:

Mark Hall (mhall{[at]}pentaho.org)

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	ReservoirSamplingData.PROC_MODE

Nested classes/interfaces inherited from class org.pentaho.di.trans.step.BaseStepData

BaseStepData.StepExecutionStatus

Field Summary

Fields

Modifier and Type	Field and Description
protected int	m_currentRow
protected int	m_k
protected RowMetaInterface	m_outputRowMeta
protected Random	m_random
protected List<Object[]>	m_sample
protected ReservoirSamplingData.PROC_MODE	m_state

Constructor Summary

Constructors

Constructor and Description
ReservoirSamplingData()

Method Summary

Modifier and Type	Method and Description
void	cleanUp()
RowMetaInterface	getOutputRowMeta() Get the output meta data
ReservoirSamplingData.PROC_MODE	getProcessingMode() Determine the current operational state of the Reservoir Sampling step.
List<Object[]>	getSample() Gets the sample as an array of rows
void	initialize(int sampleSize, int seed) Initialize this data object
void	processRow(Object[] row) Here is where the action happens.
void	setOutputRowMeta(RowMetaInterface rmi) Set the meta data for the output format
void	setProcessingMode(ReservoirSamplingData.PROC_MODE state) Set this component to sample, pass through or be disabled

Methods inherited from class org.pentaho.di.trans.step.BaseStepData

getStatus, isDisposed, isEmpty, isFinished, isIdle, isInitialising, isRunning, isStopped, setStatus

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.pentaho.di.trans.step.StepDataInterface

getStatus, isDisposed, isEmpty, isFinished, isIdle, isInitialising, isRunning, setStatus

Field Detail

m_outputRowMeta

protected RowMetaInterface m_outputRowMeta

m_sample

protected List<Object[]> m_sample

m_k

protected int m_k

m_currentRow

protected int m_currentRow

m_random

protected Random m_random

m_state

protected ReservoirSamplingData.PROC_MODE m_state

Constructor Detail

ReservoirSamplingData

public ReservoirSamplingData()

Method Detail

setOutputRowMeta

public void setOutputRowMeta(RowMetaInterface rmi)

Set the meta data for the output format

Parameters:

rmi - a RowMetaInterface value

getOutputRowMeta

public RowMetaInterface getOutputRowMeta()

Get the output meta data

Returns:

a RowMetaInterface value

getSample

public List<Object[]> getSample()

Gets the sample as an array of rows

Returns:

the sampled rows

initialize

public void initialize(int sampleSize,
                       int seed)

Initialize this data object

Parameters:

sampleSize - the number of rows to sample

seed - the seed for the random number generator

getProcessingMode

public ReservoirSamplingData.PROC_MODE getProcessingMode()

Determine the current operational state of the Reservoir Sampling step. Sampling, PassThrough(Do not wait until end, pass through on the fly), Disabled.

Returns:

current operational state

setProcessingMode

public void setProcessingMode(ReservoirSamplingData.PROC_MODE state)

Set this component to sample, pass through or be disabled

Parameters:

state - member of PROC_MODE enumeration indicating the desired operational state

processRow

public void processRow(Object[] row)

Here is where the action happens. Sampling is done using the "R" algorithm of Jeffrey Scott Vitter.

Parameters:

row - an incoming row

cleanUp

public void cleanUp()