Object
- ExpressionAbstract
- - DefaultExpression
  - - ClassificationFunction

All Implemented Interfaces:

Expression, Function, FunctionExpression, Factory

Direct Known Subclasses:

AbstractQuantityClassificationFunction, EqualIntervalFunction, JenksNaturalBreaksFunction, StandardDeviationFunction, UniqueIntervalFunction
```
public abstract class ClassificationFunction
extends DefaultExpression
implements FunctionExpression
```
Parent for classifiers which break a feature collection into the specified number of classes.

Author:

James Macgill, Cory Horner, Refractions Research Inc.

Field Summary

Fields
Modifier and Type Field Description

protected static Logger LOGGER
- Fields inherited from interface Expression
  NIL

Constructor Summary

Constructors
Constructor Description

ClassificationFunction(FunctionName name)

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`Object`	`accept(ExpressionVisitor visitor, Object extraData)`	Accepts a visitor.
`protected double[]`	`computeGroupByPercentages(FeatureCollection collection, double[] percentages, int totalSize, double min, double classWidth)`	This method return percentages by using a single groupBy query to retrieve class members.
`protected void`	`computePercentage(double[] percentages, double classMembers, double totalSize, int index)`	Compute the percentage from the input parameters, setting in the percentages array at the specified index
`protected int`	`decimalPlaces(double slotWidth)`	Determines the number of decimal places to truncate the interval at.
`abstract Object`	`evaluate(Object arg)`	Subclass should override, default implementation returns null.
`protected double`	`fixRound(double value, int decimalPlaces, boolean up)`	Corrects a round off operation by incrementing or decrementing the decimal place (preferably the smallest one).
`int`	`getClasses()`
`Literal`	`getFallbackValue()`	The value of the fallbackValue attribute is used as a default value, if the SE implementation does not support the function.
`FunctionName`	`getFunctionName()`	Access to the FunctionName description as used in a FilterCapabilities document.
`Map<RenderingHints.Key,?>`	`getImplementationHints()`	Returns the implementation hints.
`String`	`getName()`	Gets the name of this function.
`List<Expression>`	`getParameters()`	Returns the function parameters (the contents are Expressions, usually attribute expression and literal expression).
`ProgressListener`	`getProgressListener()`
`protected double`	`round(double value, int decimalPlaces)`	Truncates a double to a certain number of decimals places.
`void`	`setClasses(int classes)`
`void`	`setFallbackValue(Literal fallback)`	Fallback value to use in the event the function is unavailable in the requested environment.
`void`	`setParameters(List<Expression> params)`	Sets the function parameters.
`void`	`setProgressListener(ProgressListener progress)`
`String`	`toString()`	Creates a String representation of this Function with the function name and the arguments.

Methods inherited from class DefaultExpression
isAttributeExpression, isExpression, isFunctionExpression, isGeometryExpression, isLiteralExpression, isMathExpression

Methods inherited from class ExpressionAbstract
evaluate

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

Methods inherited from interface Expression
evaluate

- Field Detail
  - LOGGER
```
protected static final Logger LOGGER
```
- Constructor Detail
  - ClassificationFunction
```
public ClassificationFunction(FunctionName name)
```
- Method Detail
  - accept
```
public Object accept(ExpressionVisitor visitor,
                     Object extraData)
```
    Description copied from interface: Expression
    Accepts a visitor. Subclasses must implement with a method whose content is the following:
    return visitor.visit(this, extraData);
    Specified by:
    
    accept in interface Expression
    
    See Also:
    
    Expression.accept(ExpressionVisitor, Object)
  - evaluate
```
public abstract Object evaluate(Object arg)
```
    Description copied from class: ExpressionAbstract
    
    Subclass should override, default implementation returns null.
    
    Specified by:
    
    evaluate in interface Expression
    
    Overrides:
    
    evaluate in class ExpressionAbstract
    
    Returns:
    
    default implementation returns null
  - setFallbackValue
```
public void setFallbackValue(Literal fallback)
```
    Description copied from interface: FunctionExpression
    
    Fallback value to use in the event the function is unavailable in the requested environment.
    The fallback value is not provided as one of the arguments, as it is an advanced option used in style layer descriptor documents to facilitate interoperability. It allows a user to specify an SQL function, and provide a value to use when the documented is used with a WFS that does not support the provided function.
    
    Specified by:
    
    setFallbackValue in interface FunctionExpression
  - getFallbackValue
```
public Literal getFallbackValue()
```
    Description copied from interface: Function
    
    The value of the fallbackValue attribute is used as a default value, if the SE implementation does not support the function. If the implementation supports the function, then the result value is determined by executing the function.
    
    Specified by:
    
    getFallbackValue in interface Function
    
    Returns:
    
    Optional literal to use if an implementation for this function is not available.
  - getName
```
public String getName()
```
    Gets the name of this function.
    
    Specified by:
    
    getName in interface Function
    
    Returns:
    
    the name of the function.
  - getFunctionName
```
public FunctionName getFunctionName()
```
    Description copied from interface: Function
    
    Access to the FunctionName description as used in a FilterCapabilities document.
    
    Specified by:
    
    getFunctionName in interface Function
    
    Returns:
    
    FunctionName description, if available.
  - getParameters
```
public List<Expression> getParameters()
```
    Returns the function parameters (the contents are Expressions, usually attribute expression and literal expression).
    
    Specified by:
    
    getParameters in interface Function
  - setParameters
```
public void setParameters(List<Expression> params)
```
    Sets the function parameters.
    
    Specified by:
    
    setParameters in interface FunctionExpression
  - getProgressListener
```
public ProgressListener getProgressListener()
```
  - setProgressListener
```
public void setProgressListener(ProgressListener progress)
```
  - getClasses
```
public int getClasses()
```
  - setClasses
```
public void setClasses(int classes)
```
  - getImplementationHints
```
public Map<RenderingHints.Key,?> getImplementationHints()
```
    Returns the implementation hints. The default implementation returns an empty map.
    
    Specified by:
    
    getImplementationHints in interface Factory
    
    Returns:
    
    The map of hints, or an {@linkplain java.util.Collections.emptyMap() empty map} if none.
  - decimalPlaces
```
protected int decimalPlaces(double slotWidth)
```
    Determines the number of decimal places to truncate the interval at.
  - round
```
protected double round(double value,
                       int decimalPlaces)
```
    Truncates a double to a certain number of decimals places. Note: truncation at zero decimal places will still show up as x.0, since we're using the double type.
    
    Parameters:
    
    value - number to round-off
    
    decimalPlaces - number of decimal places to leave
    
    Returns:
    
    the rounded value
  - fixRound
```
protected double fixRound(double value,
                          int decimalPlaces,
                          boolean up)
```
    Corrects a round off operation by incrementing or decrementing the decimal place (preferably the smallest one). This should usually be used to adjust the bounds to include a value. Example: 0.31-->0.44 where 0.44 is the maximum value and end of the range. We could just make the , round(0.31, 1)=0.3; round(0.44 max value = 0.49
  - toString
```
public String toString()
```
    Creates a String representation of this Function with the function name and the arguments.
    
    Overrides:
    
    toString in class Object
  - computeGroupByPercentages
```
protected double[] computeGroupByPercentages(FeatureCollection collection,
                                             double[] percentages,
                                             int totalSize,
                                             double min,
                                             double classWidth)
                                      throws IOException
```
    This method return percentages by using a single groupBy query to retrieve class members. Can be used if the class width is the same for all the classes.
    
    Parameters:
    
    collection - the feature collection to classify
    
    percentages - the array of percentages to fill
    
    totalSize - the totalSize of the collection
    
    min - the min attribute value in the collection
    
    classWidth - the classWidth
    
    Returns:
    
    Throws:
    
    IOException
  - computePercentage
```
protected void computePercentage(double[] percentages,
                                 double classMembers,
                                 double totalSize,
                                 int index)
```
    Compute the percentage from the input parameters, setting in the percentages array at the specified index

Class ClassificationFunction

Field Summary

Fields inherited from interface Expression

Constructor Summary

Method Summary

Methods inherited from class DefaultExpression

Methods inherited from class ExpressionAbstract

Methods inherited from class Object

Methods inherited from interface Expression

Field Detail

LOGGER

Constructor Detail

ClassificationFunction

Method Detail

accept

evaluate

setFallbackValue

getFallbackValue

getName

getFunctionName

getParameters

setParameters

getProgressListener

setProgressListener

getClasses

setClasses

getImplementationHints

decimalPlaces

round

fixRound

toString

computeGroupByPercentages

computePercentage