weka.knowledgeflow.steps

Class FlowByExpression

java.lang.Object

weka.knowledgeflow.steps.BaseStep

weka.knowledgeflow.steps.FlowByExpression

All Implemented Interfaces:

java.io.Serializable, BaseStepExtender, Step

@KFStep(name="FlowByExpression",
        category="Flow",
        toolTipText="Route instances according to the evaluation of a logical expression. The expression can test the values of one or more incoming attributes. The test can involve constants or comparing one attribute\'s values to another. Inequalities along with string operations such as contains, starts-with, ends-with and regular expressions may be used as operators. \"True\" instances can be sent to one downstream step and \"False\" instances sent to another.",
        iconPath="weka/gui/knowledgeflow/icons/FlowByExpression.png")
public class FlowByExpression
extends BaseStep

A step that splits incoming instances (or instance streams) according to the evaluation of a logical expression. The expression can test the values of one or more incoming attributes. The test can involve constants or comparing one attribute's values to another. Inequalities along with string operations such as contains, starts-with, ends-with and regular expressions may be used as operators.

Version:

$Revision: $

Author:

Mark Hall (mhall{[at]}pentaho{[dot]}com)

See Also:

Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	FlowByExpression.BracketNode An expression node that encloses other expression nodes in brackets
static class	FlowByExpression.ExpressionClause An expression node that represents a clause of an expression
static class	FlowByExpression.ExpressionNode Abstract base class for parts of a boolean expression.

Constructor Summary

Constructors

Constructor and Description
FlowByExpression()

Method Summary

Modifier and Type	Method and Description
java.lang.String	getCustomEditorForStep() Return the fully qualified name of a custom editor component (JComponent) to use for editing the properties of the step.
java.util.List<java.lang.String>	getDownstreamStepNames() Get a list of the names of connected downstream steps
java.lang.String	getExpressionString() Get the current expression (in internal format)
java.lang.String	getFalseStepName() Get the name of the connected step to send "false" instances to
java.util.List<java.lang.String>	getIncomingConnectionTypes() Get a list of incoming connection types that this step can accept.
java.util.List<java.lang.String>	getOutgoingConnectionTypes() Get a list of outgoing connection types that this step can produce.
java.lang.String	getTrueStepName() Get the name of the connected step to send "true" instances to
Instances	outputStructureForConnectionType(java.lang.String connectionName) If possible, get the output structure for the named connection type as a header-only set of instances.
void	processIncoming(Data data) Main processing routine
void	setExpressionString(java.lang.String expressionString) Set the expression (in internal format)
void	setFalseStepName(java.lang.String falseStep) Set the name of the connected step to send "false" instances to
void	setTrueStepName(java.lang.String trueStep) Set the name of the connected step to send "true" instances to
void	stepInit() Initialize the step.

Methods inherited from class weka.knowledgeflow.steps.BaseStep

environmentSubstitute, getDefaultSettings, getInteractiveViewers, getInteractiveViewersImpls, getName, getStepManager, globalInfo, isResourceIntensive, isStopRequested, outputStructureForConnectionType, setName, setStepIsResourceIntensive, setStepManager, setStepMustRunSingleThreaded, start, stepMustRunSingleThreaded, stop

Methods inherited from class java.lang.Object

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

Constructor Detail

FlowByExpression

public FlowByExpression()

Method Detail

setExpressionString

public void setExpressionString(java.lang.String expressionString)

Set the expression (in internal format)

Parameters:

expressionString - the expression to use (in internal format)

getExpressionString

public java.lang.String getExpressionString()

Get the current expression (in internal format)

Returns:

the current expression (in internal format)

setTrueStepName

public void setTrueStepName(java.lang.String trueStep)

Set the name of the connected step to send "true" instances to

Parameters:

trueStep - the name of the step to send "true" instances to

getTrueStepName

public java.lang.String getTrueStepName()

Get the name of the connected step to send "true" instances to

Returns:

the name of the step to send "true" instances to

setFalseStepName

public void setFalseStepName(java.lang.String falseStep)

Set the name of the connected step to send "false" instances to

Parameters:

falseStep - the name of the step to send "false" instances to

getFalseStepName

public java.lang.String getFalseStepName()

Get the name of the connected step to send "false" instances to

Returns:

the name of the step to send "false" instances to

getDownstreamStepNames

public java.util.List<java.lang.String> getDownstreamStepNames()

Get a list of the names of connected downstream steps

Returns:

a list of the names of connected downstream steps

stepInit

public void stepInit()
              throws WekaException

Initialize the step.

Throws:

WekaException - if a problem occurs during initialization

getIncomingConnectionTypes

public java.util.List<java.lang.String> getIncomingConnectionTypes()

Get a list of incoming connection types that this step can accept. Ideally (and if appropriate), this should take into account the state of the step and any existing incoming connections. E.g. a step might be able to accept one (and only one) incoming batch data connection.

Returns:

a list of incoming connections that this step can accept given its current state

getOutgoingConnectionTypes

public java.util.List<java.lang.String> getOutgoingConnectionTypes()

Get a list of outgoing connection types that this step can produce. Ideally (and if appropriate), this should take into account the state of the step and the incoming connections. E.g. depending on what incoming connection is present, a step might be able to produce a trainingSet output, a testSet output or neither, but not both.

Returns:

a list of outgoing connections that this step can produce

outputStructureForConnectionType

public Instances outputStructureForConnectionType(java.lang.String connectionName)
                                           throws WekaException

If possible, get the output structure for the named connection type as a header-only set of instances. Can return null if the specified connection type is not representable as Instances or cannot be determined at present.

Specified by:

outputStructureForConnectionType in interface Step

Overrides:

outputStructureForConnectionType in class BaseStep

Parameters:

connectionName - the name of the connection type to get the output structure for

Returns:

the output structure as a header-only Instances object

Throws:

WekaException - if a problem occurs

processIncoming

public void processIncoming(Data data)
                     throws WekaException

Main processing routine

Specified by:

processIncoming in interface BaseStepExtender

Specified by:

processIncoming in interface Step

Overrides:

processIncoming in class BaseStep

Parameters:

data - incoming data object

Throws:

WekaException - if a problem occurs

getCustomEditorForStep

public java.lang.String getCustomEditorForStep()

Return the fully qualified name of a custom editor component (JComponent) to use for editing the properties of the step. This method can return null, in which case the system will dynamically generate an editor using the GenericObjectEditor

Specified by:

getCustomEditorForStep in interface Step

Overrides:

getCustomEditorForStep in class BaseStep

Returns:

the fully qualified name of a step editor component