www.pudn.com > zuixindeID3.zip > AttrCategorizer.java

package id3; 
import java.lang.*; 
import java.io.*; 
import shared.*; 
import shared.Error; 
 
/** The AttrCategorizer categorizes an Instance based on an attribute. 
 * Assumes the attribute is of a type derived from Nominal. 
 * @author James Louis	2/25/2001	Ported to Java. 
 * @author Chia-Hsin Li	11/23/94	Add operator== 
 * @author Ronny Kohavi	8/02/93	Initial revision 
 */ 
public class AttrCategorizer extends NodeCategorizer { 
    /** The number of the specific attribute in this AttrCategorizer. **/ 
    private int attrNum; 
    /** The information on labels and attributes. **/ 
    private AttrInfo attrInfo; 
     
    /** Constructor. 
     * @param schma		The schema for this categorizer. 
     * @param attributeNum	The number of the specific attribute in the schema 
     * for the data. 
     * @param dscr			The description of this categorizer. 
     */ 
    public AttrCategorizer(Schema schma, int attributeNum, String dscr) { 
        super(num_nominal_attr(schma, attributeNum), dscr, schma); 
        try { 
            attrInfo =(AttrInfo) schma.attr_info(attributeNum).clone(); 
        } catch(CloneNotSupportedException e) { 
            System.out.println(e.toString()); 
        } 
        attrNum = attributeNum; 
    } 
     
    /** Finds the number of attributes that are nominal in nature. 
     * @return The number of nominal attributes. 
     * @param schema	The schema containing attribute and label information. 
     * @param attrNum	The number of the specific attribute in the schema for 
     * the data. 
     */ 
    public static int num_nominal_attr(Schema schema, int attrNum) { 
        if (attrNum < 0) 
            Error.fatalErr("AttrCategorizer::num_nominal_attr: Bad attribute number: " + 
            attrNum); 
         
        // find the matching schema 
        NominalAttrInfo nai = schema.nominal_attr_info(attrNum); 
        return nai.num_values(); 
    } 
     
    /** Identifies the class. 
     * @deprecated Java's instanceof operator should be used instead. 
     * @return A value uniquely identifying this object as an AttrCategorizer. 
     */ 
    public int class_id() { 
        return CLASS_ATTR_CATEGORIZER; 
    } 
     
    /** Choses the child branch that the given instance would go down. Used 
     * for scoring, categorization, and splitting of InstanceLists. 
     * @return The AugCategory that correlates to the specified Instance. 
     * @param inst	The specified Instance. 
     */ 
    public AugCategory branch(Instance inst) { 
        //      if (Globals.DBG) inst.attr_info(attrNum).compatible_with(attrInfo, true); 
        AttrValue val = inst.values[attrNum]; 
        String dscr = attrInfo.attrValue_to_string(val); 
        AugCategory ac = new AugCategory(attrInfo.get_nominal_val(val) , dscr); 
        return ac; 
    } 
     
    /** Prints a readable representation of the Categorizer to the given stream. 
     * @param stream	The output stream to be written to. 
     * @param dp		The preference settings for the display. 
     */ 
    public void display_struct(BufferedWriter stream, 
    DisplayPref dp) { 
        //   if (stream.output_type() == XStream) 
        //      err << "AttrCategorizer::display_struct: Xstream is not a supported " 
        //             "stream"  << fatal_error; 
         
        //   if (dp.preference_type() != DisplayPref::ASCIIDisplay) 
        //      err << "AttrCategorizer::display_struct: Only ASCIIDisplay is " 
        //             "supported by AttrCategorizer"  << fatal_error; 
        try { 
            stream.write("Attribute Categorizer " +description() 
            + " categorizing on attribute " +attrInfo.name() + '\n'); 
        } catch(IOException e) { 
            e.printStackTrace(); 
        } 
    } 
     
    /** Updates usedAttr to include the attributes used in this categorizer. 
     * @param usedAttr A boolean array representing attributes. Each element set 
     * to TRUE indicates the attribute is used. It is FALSE 
     * otherwise. This method sets the appropriate attribute 
     * element to true. 
     */ 
    public void set_used_attr(boolean[] usedAttr) { 
        MLJ.ASSERT((attrNum >= 0)&&(attrNum < usedAttr.length), 
        "AttrCategorizer::set_used_attr: " 
        + "attrNum is not between 0 and usedAttr.length"); 
        usedAttr[attrNum] = true; 
    } 
     
}