SubsetByExpression (weka-stable 3.6.8 API)

java.lang.Object
- weka.filters.Filter
- - weka.filters.SimpleFilter
  - - weka.filters.SimpleBatchFilter
    - - weka.filters.unsupervised.instance.SubsetByExpression

All Implemented Interfaces:

Serializable, CapabilitiesHandler, OptionHandler, RevisionHandler
```
public class SubsetByExpression
extends SimpleBatchFilter
```
Filters instances according to a user-specified expression.

Grammar:

boolexpr_list ::= boolexpr_list boolexpr_part | boolexpr_part;

boolexpr_part ::= boolexpr:e {: parser.setResult(e); :} ;

boolexpr ::= BOOLEAN
| true
| false
| expr < expr
| expr <= expr
| expr > expr
| expr >= expr
| expr = expr
| ( boolexpr )
| not boolexpr
| boolexpr and boolexpr
| boolexpr or boolexpr
| ATTRIBUTE is STRING
;

expr ::= NUMBER
| ATTRIBUTE
| ( expr )
| opexpr
| funcexpr
;

opexpr ::= expr + expr
| expr - expr
| expr * expr
| expr / expr
;

funcexpr ::= abs ( expr )
| sqrt ( expr )
| log ( expr )
| exp ( expr )
| sin ( expr )
| cos ( expr )
| tan ( expr )
| rint ( expr )
| floor ( expr )
| pow ( expr for base , expr for exponent )
| ceil ( expr )
;

Notes:
- NUMBER
any integer or floating point number
(but not in scientific notation!)
- STRING
any string surrounded by single quotes;
the string may not contain a single quote though.
- ATTRIBUTE
the following placeholders are recognized for
attribute values:
- CLASS for the class value in case a class attribute is set.
- ATTxyz with xyz a number from 1 to # of attributes in the
dataset, representing the value of indexed attribute.

Examples:
- extracting only mammals and birds from the 'zoo' UCI dataset:
(CLASS is 'mammal') or (CLASS is 'bird')
- extracting only animals with at least 2 legs from the 'zoo' UCI dataset:
(ATT14 >= 2)
- extracting only instances with non-missing 'wage-increase-second-year'
from the 'labor' UCI dataset:
not ismissing(ATT3)

Valid options are:
```
 -E <expr>
  The expression to use for filtering
  (default: true).
```
```
 -F
  Apply the filter to instances that arrive after the first
  (training) batch. The default is to not apply the filter (i.e.
  always return the instance)
```
Version:

$Revision: 7599 $

Author:

fracpete (fracpete at waikato dot ac dot nz)

See Also:

Serialized Form

Field Summary

Fields
Modifier and Type	Field and Description
`protected String`	`m_Expression` the expresion to use for filtering.
`protected boolean`	`m_filterAfterFirstBatch` Whether to filter instances after the first batch has been processed

Fields inherited from class weka.filters.SimpleFilter
m_Debug

Fields inherited from class weka.filters.Filter
m_FirstBatchDone, m_InputRelAtts, m_InputStringAtts, m_NewBatch, m_OutputRelAtts, m_OutputStringAtts

Constructor Summary

Constructors
Constructor and Description

SubsetByExpression()

Constructors
Constructor and Description
`SubsetByExpression()`

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`protected Instances`	`determineOutputFormat(Instances inputFormat)` Determines the output format based on the input format and returns this.
`String`	`expressionTipText()` Returns the tip text for this property.
`String`	`filterAfterFirstBatchTipText()` Returns the tip text for this property.
`Capabilities`	`getCapabilities()` Returns the Capabilities of this filter.
`String`	`getExpression()` Returns the expression used for filtering.
`boolean`	`getFilterAfterFirstBatch()` Get whether to apply the filter to instances that arrive once the first (training) batch has been seen.
`String[]`	`getOptions()` Gets the current settings of the filter.
`String`	`getRevision()` Returns the revision string.
`String`	`globalInfo()` Returns a string describing this filter.
`boolean`	`input(Instance instance)` Input an instance for filtering.
`Enumeration`	`listOptions()` Returns an enumeration describing the available options.
`static void`	`main(String[] args)` Main method for running this filter.
`protected Instances`	`process(Instances instances)` Processes the given data (may change the provided dataset) and returns the modified version.
`void`	`setExpression(String value)` Sets the expression used for filtering.
`void`	`setFilterAfterFirstBatch(boolean b)` Set whether to apply the filter to instances that arrive once the first (training) batch has been seen.
`void`	`setOptions(String[] options)` Parses a given list of options.

Methods inherited from class weka.filters.SimpleBatchFilter
batchFinished, hasImmediateOutputFormat

Methods inherited from class weka.filters.SimpleFilter
debugTipText, getDebug, reset, setDebug, setInputFormat

Methods inherited from class weka.filters.Filter
batchFilterFile, bufferInput, copyValues, copyValues, filterFile, flushInput, getCapabilities, getInputFormat, getOutputFormat, initInputLocators, initOutputLocators, inputFormatPeek, isFirstBatchDone, isNewBatch, isOutputFormatDefined, makeCopies, makeCopy, numPendingOutput, output, outputFormatPeek, outputPeek, push, resetQueue, runFilter, setOutputFormat, testInputFormat, toString, useFilter, wekaStaticWrapper

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Field Detail
  - m_Expression
```
protected String m_Expression
```
    the expresion to use for filtering.
  - m_filterAfterFirstBatch
```
protected boolean m_filterAfterFirstBatch
```
    Whether to filter instances after the first batch has been processed
- Constructor Detail
  - SubsetByExpression
```
public SubsetByExpression()
```
- Method Detail
  - globalInfo
```
public String globalInfo()
```
    Returns a string describing this filter.
    
    Specified by:
    
    globalInfo in class SimpleFilter
    
    Returns:
    
    a description of the filter suitable for displaying in the explorer/experimenter gui
  - input
```
public boolean input(Instance instance)
              throws Exception
```
    Input an instance for filtering. Filter requires all training instances be read before producing output (calling the method batchFinished() makes the data available). If this instance is part of a new batch, m_NewBatch is set to false.
    
    Overrides:
    
    input in class SimpleBatchFilter
    
    Parameters:
    
    instance - the input instance
    
    Returns:
    
    true if the filtered instance may now be collected with output().
    
    Throws:
    
    IllegalStateException - if no input structure has been defined
    
    Exception - if something goes wrong
    
    See Also:
    
    SimpleBatchFilter.batchFinished()
  - listOptions
```
public Enumeration listOptions()
```
    Returns an enumeration describing the available options.
    
    Specified by:
    
    listOptions in interface OptionHandler
    
    Overrides:
    
    listOptions in class SimpleFilter
    
    Returns:
    
    an enumeration of all the available options.
  - setOptions
```
public void setOptions(String[] options)
                throws Exception
```
    Parses a given list of options.
    Valid options are:
```
 -E <expr>
  The expression to use for filtering
  (default: true).
```
```
 -F
  Apply the filter to instances that arrive after the first
  (training) batch. The default is to not apply the filter (i.e.
  always return the instance)
```
    Specified by:
    
    setOptions in interface OptionHandler
    
    Overrides:
    
    setOptions in class SimpleFilter
    
    Parameters:
    
    options - the list of options as an array of strings
    
    Throws:
    
    Exception - if an option is not supported
    
    See Also:
    
    SimpleFilter.reset()
  - getOptions
```
public String[] getOptions()
```
    Gets the current settings of the filter.
    
    Specified by:
    
    getOptions in interface OptionHandler
    
    Overrides:
    
    getOptions in class SimpleFilter
    
    Returns:
    
    an array of strings suitable for passing to setOptions
  - getCapabilities
```
public Capabilities getCapabilities()
```
    Returns the Capabilities of this filter.
    
    Specified by:
    
    getCapabilities in interface CapabilitiesHandler
    
    Overrides:
    
    getCapabilities in class Filter
    
    Returns:
    
    the capabilities of this object
    
    See Also:
    
    Capabilities
  - setExpression
```
public void setExpression(String value)
```
    Sets the expression used for filtering.
    
    Parameters:
    
    value - the expression
  - getExpression
```
public String getExpression()
```
    Returns the expression used for filtering.
    
    Returns:
    
    the expression
  - expressionTipText
```
public String expressionTipText()
```
    Returns the tip text for this property.
    
    Returns:
    
    tip text for this property suitable for displaying in the explorer/experimenter gui
  - setFilterAfterFirstBatch
```
public void setFilterAfterFirstBatch(boolean b)
```
    Set whether to apply the filter to instances that arrive once the first (training) batch has been seen. The default is to not apply the filter and just return each instance input. This is so that, when used in the FilteredClassifier, a test instance does not get "consumed" by the filter and a prediction is always generated.
    
    Parameters:
    
    b - true if the filter should be applied to instances that arrive after the first (training) batch has been processed.
  - getFilterAfterFirstBatch
```
public boolean getFilterAfterFirstBatch()
```
    Get whether to apply the filter to instances that arrive once the first (training) batch has been seen. The default is to not apply the filter and just return each instance input. This is so that, when used in the FilteredClassifier, a test instance does not get "consumed" by the filter and a prediction is always generated.
    
    Returns:
    
    true if the filter should be applied to instances that arrive after the first (training) batch has been processed.
  - filterAfterFirstBatchTipText
```
public String filterAfterFirstBatchTipText()
```
    Returns the tip text for this property.
    
    Returns:
    
    tip text for this property suitable for displaying in the explorer/experimenter gui
  - determineOutputFormat
```
protected Instances determineOutputFormat(Instances inputFormat)
                                   throws Exception
```
    Determines the output format based on the input format and returns this.
    
    Specified by:
    
    determineOutputFormat in class SimpleFilter
    
    Parameters:
    
    inputFormat - the input format to base the output format on
    
    Returns:
    
    the output format
    
    Throws:
    
    Exception - in case the determination goes wrong
    
    See Also:
    
    SimpleFilter.hasImmediateOutputFormat(), Filter.batchFinished()
  - process
```
protected Instances process(Instances instances)
                     throws Exception
```
    Processes the given data (may change the provided dataset) and returns the modified version. This method is called in batchFinished().
    
    Specified by:
    
    process in class SimpleFilter
    
    Parameters:
    
    instances - the data to process
    
    Returns:
    
    the modified data
    
    Throws:
    
    Exception - in case the processing goes wrong
    
    See Also:
    
    SimpleBatchFilter.batchFinished()
  - getRevision
```
public String getRevision()
```
    Returns the revision string.
    
    Specified by:
    
    getRevision in interface RevisionHandler
    
    Overrides:
    
    getRevision in class Filter
    
    Returns:
    
    the revision
  - main
```
public static void main(String[] args)
```
    Main method for running this filter.
    
    Parameters:
    
    args - arguments for the filter: use -h for help

Class SubsetByExpression

Field Summary

Fields inherited from class weka.filters.SimpleFilter

Fields inherited from class weka.filters.Filter

Constructor Summary

Method Summary

Methods inherited from class weka.filters.SimpleBatchFilter

Methods inherited from class weka.filters.SimpleFilter

Methods inherited from class weka.filters.Filter

Methods inherited from class java.lang.Object

Field Detail

m_Expression

m_filterAfterFirstBatch

Constructor Detail

SubsetByExpression

Method Detail

globalInfo

input

listOptions

setOptions

getOptions

getCapabilities

setExpression

getExpression

expressionTipText

setFilterAfterFirstBatch

getFilterAfterFirstBatch

filterAfterFirstBatchTipText

determineOutputFormat

process

getRevision

main