hillclimber.java

一个数据挖掘软件ALPHAMINERR的整个过程的JAVA版源代码

		ParentSet bestParentSet = bayesNet.getParentSet(iHead);
		bestParentSet.deleteParent(iTail, instances);
		updateCache(iHead, instances.numAttributes(), bestParentSet);
	} // applyArcAddition


	/** find best (or least bad) arc addition operation
	 * @param bayesNet: Bayes network to add arc to
	 * @param instances: data set
	 * @return Operation containing best arc to add, or null if no arc addition is allowed 
	 * (this can happen if any arc addition introduces a cycle, or all parent sets are filled
	 * up to the maximum nr of parents).
	 */
	Operation findBestArcToAdd(BayesNet bayesNet, Instances instances, Operation oBestOperation) {
		int nNrOfAtts = instances.numAttributes();
		// find best arc to add
		for (int iAttributeHead = 0; iAttributeHead < nNrOfAtts; iAttributeHead++) {
			if (bayesNet.getParentSet(iAttributeHead).getNrOfParents() < m_nMaxNrOfParents) {
				for (int iAttributeTail = 0; iAttributeTail < nNrOfAtts; iAttributeTail++) {
					if (addArcMakesSense(bayesNet, instances, iAttributeHead, iAttributeTail)) {
						Operation oOperation = new Operation(iAttributeTail, iAttributeHead, Operation.OPERATION_ADD);
						if (m_Cache.get(oOperation) > oBestOperation.m_fDeltaScore) {
							if (isNotTabu(oOperation)) {
								oBestOperation = oOperation;
								oBestOperation.m_fDeltaScore = m_Cache.get(oOperation);
							}
						}
					}
				}
			}
		}
		return oBestOperation;
	} // findBestArcToAdd

	/** find best (or least bad) arc deletion operation
	 * @param bayesNet: Bayes network to delete arc from
	 * @param instances: data set
	 * @return Operation containing best arc to delete, or null if no deletion can be made 
	 * (happens when there is no arc in the network yet).
	 */
	Operation findBestArcToDelete(BayesNet bayesNet, Instances instances, Operation oBestOperation) {
		int nNrOfAtts = instances.numAttributes();
		// find best arc to delete
		for (int iNode = 0; iNode < nNrOfAtts; iNode++) {
			ParentSet parentSet = bayesNet.getParentSet(iNode);
			for (int iParent = 0; iParent < parentSet.getNrOfParents(); iParent++) {
				Operation oOperation = new Operation(parentSet.getParent(iParent), iNode, Operation.OPERATION_DEL);
				if (m_Cache.get(oOperation) > oBestOperation.m_fDeltaScore) {
					if (isNotTabu(oOperation)) {
						oBestOperation = oOperation;
						oBestOperation.m_fDeltaScore = m_Cache.get(oOperation);
					}
				}
			}
		}
		return oBestOperation;
	} // findBestArcToDelete

	/** find best (or least bad) arc reversal operation
	 * @param bayesNet: Bayes network to reverse arc in
	 * @param instances: data set
	 * @return Operation containing best arc to reverse, or null if no reversal is allowed
	 * (happens if there is no arc in the network yet, or when any such reversal introduces
	 * a cycle).
	 */
	Operation findBestArcToReverse(BayesNet bayesNet, Instances instances, Operation oBestOperation) {
		int nNrOfAtts = instances.numAttributes();
		// find best arc to reverse
		for (int iNode = 0; iNode < nNrOfAtts; iNode++) {
			ParentSet parentSet = bayesNet.getParentSet(iNode);
			for (int iParent = 0; iParent < parentSet.getNrOfParents(); iParent++) {
				int iTail = parentSet.getParent(iParent);
				// is reversal allowed?
				if (reverseArcMakesSense(bayesNet, instances, iNode, iTail) && 
				    bayesNet.getParentSet(iTail).getNrOfParents() < m_nMaxNrOfParents) {
					// go check if reversal results in the best step forward
					Operation oOperation = new Operation(parentSet.getParent(iParent), iNode, Operation.OPERATION_REVERSE);
					if (m_Cache.get(oOperation) > oBestOperation.m_fDeltaScore) {
						if (isNotTabu(oOperation)) {
							oBestOperation = oOperation;
							oBestOperation.m_fDeltaScore = m_Cache.get(oOperation);
						}
					}
				}
			}
		}
		return oBestOperation;
	} // findBestArcToReverse

	/** update the cache due to change of parent set of a node
	 * @param iAttributeHead: node that has its parent set changed
	 * @param nNrOfAtts: number of nodes/attributes in data set
	 * @param parentSet: new parents set of node iAttributeHead
	 */
	void updateCache(int iAttributeHead, int nNrOfAtts, ParentSet parentSet) {
		// update cache entries for arrows heading towards iAttributeHead
		double fBaseScore = calcNodeScore(iAttributeHead);
		int nNrOfParents = parentSet.getNrOfParents();
		for (int iAttributeTail = 0; iAttributeTail < nNrOfAtts; iAttributeTail++) {
			if (iAttributeTail != iAttributeHead) {
				if (!parentSet.contains(iAttributeTail)) {
					// add entries to cache for adding arcs
					if (nNrOfParents < m_nMaxNrOfParents) {
						Operation oOperation = new Operation(iAttributeTail, iAttributeHead, Operation.OPERATION_ADD);
						m_Cache.put(oOperation, calcScoreWithExtraParent(iAttributeHead, iAttributeTail) - fBaseScore);
					}
				} else {
					// add entries to cache for deleting arcs
					Operation oOperation = new Operation(iAttributeTail, iAttributeHead, Operation.OPERATION_DEL);
					m_Cache.put(oOperation, calcScoreWithMissingParent(iAttributeHead, iAttributeTail) - fBaseScore);
				}
			}
		}
	} // updateCache
	

	/**
	 * Method declaration
	 *
	 * @param nMaxNrOfParents
	 *
	 */
	public void setMaxNrOfParents(int nMaxNrOfParents) {
	  m_nMaxNrOfParents = nMaxNrOfParents;
	} 

	/**
	 * Method declaration
	 *
	 * @return
	 *
	 */
	public int getMaxNrOfParents() {
	  return m_nMaxNrOfParents;
	} 

	/**
	 * Returns an enumeration describing the available options.
	 *
	 * @return an enumeration of all the available options.
	 */
	public Enumeration listOptions() {
		Vector newVector = new Vector(2);

		newVector.addElement(new Option("\tMaximum number of parents\n", "P", 1, "-P <nr of parents>"));
		newVector.addElement(new Option("\tUse arc reversal operation.\n\t(default false)", "R", 0, "-R"));

		Enumeration em = super.listOptions();
		while (em.hasMoreElements()) {
			newVector.addElement(em.nextElement());
		}
		return newVector.elements();
	} // listOptions

	/**
	 * Parses a given list of options. Valid options are:<p>
	 *
	 * For other options see search algorithm.
	 *
	 * @param options the list of options as an array of strings
	 * @exception Exception if an option is not supported
	 */
	public void setOptions(String[] options) throws Exception {
		setUseArcReversal(Utils.getFlag('R', options));

		setInitAsNaiveBayes ((Utils.getFlag('N', options)));
		
		String sMaxNrOfParents = Utils.getOption('P', options);
		if (sMaxNrOfParents.length() != 0) {
		  setMaxNrOfParents(Integer.parseInt(sMaxNrOfParents));
		} else {
		  setMaxNrOfParents(100000);
		}
		
		super.setOptions(options);
	} // setOptions

	/**
	 * Gets the current settings of the search algorithm.
	 *
	 * @return an array of strings suitable for passing to setOptions
	 */
	public String[] getOptions() {
		String[] superOptions = super.getOptions();
		String[] options = new String[7 + superOptions.length];
		int current = 0;
		if (getUseArcReversal()) {
		  options[current++] = "-R";
		}
		
		if (!getInitAsNaiveBayes()) {
		  options[current++] = "-N";
		} 

		if (m_nMaxNrOfParents != 10000) {
		  options[current++] = "-P";
		  options[current++] = "" + m_nMaxNrOfParents;
		} 

		// insert options from parent class
		for (int iOption = 0; iOption < superOptions.length; iOption++) {
			options[current++] = superOptions[iOption];
		}

		// Fill up rest with empty strings, not nulls!
		while (current < options.length) {
			options[current++] = "";
		}
		return options;
	} // getOptions

	/**
	 * Method declaration
	 *
	 * @param bInitAsNaiveBayes
	 *
	 */
	public void setInitAsNaiveBayes(boolean bInitAsNaiveBayes) {
	  m_bInitAsNaiveBayes = bInitAsNaiveBayes;
	} 

	/**
	 * Method declaration
	 *
	 * @return
	 *
	 */
	public boolean getInitAsNaiveBayes() {
	  return m_bInitAsNaiveBayes;
	} 

	/** get use the arc reversal operation
	 * @return whether the arc reversal operation should be used
	 */
	public boolean getUseArcReversal() {
		return m_bUseArcReversal;
	} // getUseArcReversal

	/** set use the arc reversal operation
	 * @param bUseArcReversal whether the arc reversal operation should be used
	 */
	public void setUseArcReversal(boolean bUseArcReversal) {
		m_bUseArcReversal = bUseArcReversal;
	} // setUseArcReversal

	/**
	 * This will return a string describing the search algorithm.
	 * @return The string.
	 */
	public String globalInfo() {
	  return "This Bayes Network learning algorithm uses a hill climbing algorithm " +
	  "adding, deleting and reversing arcs. The search is not restricted by an order " +
	  "on the variables (unlike K2). The difference with B and B2 is that this hill " +
	  "climber also considers arrows part of the naive Bayes structure for deletion.";
	} // globalInfo

	/**
	 * @return a string to describe the Use Arc Reversal option.
	 */
	public String useArcReversalTipText() {
	  return "When set to true, the arc reversal operation is used in the search.";
	} // useArcReversalTipText

} // HillClimber