Package org.geotools.filter.function

Class ClassificationFunction

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 Details

    • LOGGER

      protected static final Logger LOGGER

  • Constructor Details

    • ClassificationFunction

      public ClassificationFunction(FunctionName name)

  • Method Details

    • 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:

    • 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