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Class weka.filters.AttributeExpressionFilter
java.lang.Object
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+----weka.filters.Filter
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+----weka.filters.AttributeExpressionFilter
- public class AttributeExpressionFilter
- extends Filter
- implements OptionHandler
Applys a mathematical expression involving attributes and numeric
constants to a dataset. A new attribute is appended after the last
attribute that contains the result of applying the expression.
Supported operators are: +, -, *, /, ^, log, abs, cos, exp, sqrt,
floor, ceil, rint, tan, sin, (, ). Attributes are specified
by prefixing with 'a', eg. a7 is attribute number 7 (starting from 1).
Valid filter-specific options are:
-E expression
Specify the expression to apply. Eg. a1^2*a5/log(a7*4.0).
-N name
Specify a name for the new attribute. Default is to name it with the
expression provided with the -E option.
-D
Debug. Names the attribute with the postfix parse of the expression.
- Author:
- Mark Hall (mhall@cs.waikato.ac.nz)
-
AttributeExpressionFilter()
-
-
debugTipText()
- Returns the tip text for this property
-
expressionTipText()
- Returns the tip text for this property
-
getDebug()
- Gets whether debug is set
-
getExpression()
- Get the expression
-
getName()
- Returns the name of the new attribute
-
getOptions()
- Gets the current settings of the filter.
-
globalInfo()
- Returns a string describing this filter
-
input(Instance)
- Input an instance for filtering.
-
listOptions()
- Returns an enumeration describing the available options
-
main(String[])
- Main method for testing this class.
-
nameTipText()
- Returns the tip text for this property
-
setDebug(boolean)
- Set debug mode.
-
setExpression(String)
- Set the expression to apply
-
setInputFormat(Instances)
- Sets the format of the input instances.
-
setName(String)
- Set the name for the new attribute.
-
setOptions(String[])
- Parses a list of options for this object.
AttributeExpressionFilter
public AttributeExpressionFilter()
globalInfo
public String globalInfo()
- Returns a string describing this filter
- Returns:
- a description of the filter suitable for
displaying in the explorer/experimenter gui
listOptions
public Enumeration listOptions()
- Returns an enumeration describing the available options
- Returns:
- an enumeration of all the available options
setOptions
public void setOptions(String options[]) throws Exception
- Parses a list of options for this object. Valid options are:
-E expression
Specify the expression to apply. Eg. a1^2*a5/log(a7*4.0).
-N name
Specify a name for the new attribute. Default is to name it with the
expression provided with the -E option.
-D
Debug. Names the attribute with the postfix parse of the expression.
- Parameters:
- options - the list of options as an array of strings
- Throws: Exception
- if an option is not supported
getOptions
public String[] getOptions()
- Gets the current settings of the filter.
- Returns:
- an array of strings suitable for passing to setOptions
nameTipText
public String nameTipText()
- Returns the tip text for this property
- Returns:
- tip text for this property suitable for
displaying in the explorer/experimenter gui
setName
public void setName(String name)
- Set the name for the new attribute. The string "expression" can
be used to make the name of the new attribute equal to the expression
provided.
- Parameters:
- name - the name of the new attribute
getName
public String getName()
- Returns the name of the new attribute
- Returns:
- the name of the new attribute
debugTipText
public String debugTipText()
- Returns the tip text for this property
- Returns:
- tip text for this property suitable for
displaying in the explorer/experimenter gui
setDebug
public void setDebug(boolean d)
- Set debug mode. Causes the new attribute to be named with the postfix
parse of the expression
- Parameters:
- d - true if debug mode is to be used
getDebug
public boolean getDebug()
- Gets whether debug is set
- Returns:
- true if debug is set
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
setExpression
public void setExpression(String expr)
- Set the expression to apply
- Parameters:
- expr - a mathematical expression to apply
getExpression
public String getExpression()
- Get the expression
- Returns:
- the expression
setInputFormat
public boolean setInputFormat(Instances instanceInfo) throws Exception
- Sets the format of the input instances.
- Parameters:
- instanceInfo - an Instances object containing the input instance
structure (any instances contained in the object are ignored - only the
structure is required).
- Returns:
- true if the outputFormat may be collected immediately
- Throws: Exception
- if the format couldn't be set successfully
- Overrides:
- setInputFormat in class Filter
input
public boolean input(Instance instance) throws Exception
- Input an instance for filtering. Ordinarily the instance is processed
and made available for output immediately. Some filters require all
instances be read before producing output.
- Parameters:
- instance - the input instance
- Returns:
- true if the filtered instance may now be
collected with output().
- Throws: IllegalStateException
- if no input format has been defined.
- Throws: Exception
- if there was a problem during the filtering.
- Overrides:
- input in class Filter
main
public static void main(String args[])
- Main method for testing this class.
- Parameters:
- args - should contain arguments to the filter: use -h for help
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