itemset.java

apriori演算法於JAVA環境下開發 用於資料探勘分類產生規則

/**
 * @(#)ItemSet.java
 *
 * This class represents a single candidate itemset and its support.
 *
 * @author Adrian Bright
 */
import java.util.*;

class ItemSet
{
	/* The list of items contained in the itemset */
	private LinkedList items;
	/* The support count of the itemset */
	private int support;
	
	/**
     * ItemSet Initialises the ItemSet.
     */
	public ItemSet()
	{
		items = new LinkedList();
		support = 0;
	}
	
	/**
     * ItemSet Initialises the ItemSet with a list of new items.
	 * @param newItems List of new items.
     */
	public ItemSet(LinkedList newItems)
	{
		items = newItems;
		support = 0;
	}

	/**
     * setOneItem Adds an item to the itemset.
	 * @param attribute The new item to be added.
     */
	public void setOneItem(String attribute)
	{
		items.add(attribute);
	}

	/**
     * setItems Adds multiple items to the itemset.
	 * @param attributes The new items to be added.
     */
	public void setItems(LinkedList attributes)
	{
		items.addAll(attributes);
	}

	/**
     * incrementSupport Increments the support count of the itemset.
     */
	public void incrementSupport()
	{
		support++;
	}

	/**
     * getItem Returns the item at the specified point in the itemset.
	 * @param index Identifies the position in the itemset.
	 * @return The item at the specified position in the itemset.
     */
	public String getItem(int index)
	{
		return (String)items.get(index);
	}

	/**
     * getItems Returns all the items in the itemset.
	 * @return The items in the itemset.
     */
	public LinkedList getItems()
	{
		return items;
	}

	/**
     * getSupport Returns the support count of the itemset.
	 * @return The support count of the itemset.
     */
	public int getSupport()
	{
		return support;
	}

	/**
     * size Returns the size of the itemset.
	 * @return The size of the itemset.
     */
	public int size()
	{
		return items.size();
	}

	/**
     * printItems Prints the itemset to screen.
     */
	public void printItems()
	{
		ListIterator it = items.listIterator(0);
		System.out.print("|itemset size" + items.size() + ": ");
		while (it.hasNext())
		{
			System.out.print((String)it.next());
		}
		System.out.println(", support " + getSupport() + "|");
	}

	/**
     * itemsString Returns the itemset in its name form (not id form) in
	 * the format of {a,b,c}.
	 * @param itemsRef The identifiers of each item.
	 * @return The itemset in name form.
     */
	public String itemsString(LinkedList itemsRef)
	{
		String itemset = "{";
		String currentItem;
		ItemRef itemRef;
		ListIterator it = items.listIterator(0);
		ListIterator itRef; 
		while (it.hasNext())
		{
			currentItem = (String)it.next();
			itRef = itemsRef.listIterator(0);
			itemRef = new ItemRef();
			while ((itRef.hasNext()) && (!(itemRef.getItemID().equals(currentItem))))
			{
				itemRef = (ItemRef)itRef.next();
			}
			itemset += itemRef.getItemName() + ",";
		}
		itemset = itemset.substring(0,itemset.length()-1);
		itemset += "}";
		return itemset;
	}
}