UniformChoice.java

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package blog.distrib;

import java.util.*;
import blog.*;
import common.Util;



CPD that takes a set of objects (an instance of the ObjectSet interface) as an argument, and defines a uniform distribution over this set.


public class UniformChoice extends AbstractCondProbDistrib {
    

Creates a UniformChoice CPD. This constructor is not used by the parser, which looks for a constructor taking a List as an argument. Instead, it's used when we create a UniformChoice CPD in the program.


    public UniformChoice() {
    }

    

Creates a UniformChoice CPD. The CPD takes no parameters.

Throws:  IllegalArgumentException if params is non-empty


    public UniformChoice(List params) {
	if (!params.isEmpty()) {
	    throw new IllegalArgumentException
		("UniformChoice CPD does not take any parameters.");
	}
    }

    

Takes a single argument, namely a set S. If S is non-empty, returns 1 / |S| if value is in S, and otherwise 0. If S is empty, returns 1 if the value is Model.NULL, and 0 otherwise. other than a single argument of class ObjectSet.

Throws:  IllegalArgumentException if args contains anything


    public double getProb(List args, Object value) {
	ObjectSet s = processArgs(args);
	//if (!s.contains(value)) {
	//   System.out.println("UniformChoice: " + value + " is not in " + s);
	    //    System.out.println("Explicit version of set is: " 
	    //	       + new ArrayList(s));
	//}
	if (s.isEmpty()) {
	    return (value == Model.NULL) ? 1 : 0;
	}
	return (s.contains(value) ? (1.0 / s.size()) : 0);
    }

    

Takes a single argument, namely a finite set S. Returns an element of S selected uniformly at random. If S is empty, returns Model.NULL. other than a single argument of class ObjectSet.

Throws:  IllegalArgumentException if args contains anything


    public Object sampleVal(List args, Type childType) {
	ObjectSet s = processArgs(args);
	if (s.isEmpty()) {
	    return Model.NULL;
	}
	int n = Util.randInt(s.size());
	return s.sample(n);
    }

    private ObjectSet processArgs(List args) {
	if (args.size() != 1) {
	    throw new IllegalArgumentException
		("UniformChoice CPD takes exactly one argument.");
	}
	if (!(args.get(0) instanceof ObjectSet)) {
	    throw new IllegalArgumentException
		("UniformChoice CPD takes an argument of class ObjectSet, "
		 + "not one of " 
		 + args.get(0).getClass() + ".");
	}

	return (ObjectSet) args.get(0);
    }
}


This file was generated on Tue Jun 08 17:53:48 PDT 2010 from file UniformChoice.java
by the ilog.language.tools.Hilite Java tool written by Hassan Aït-Kaci