java.lang.Object
- weka.associations.ItemSet

All Implemented Interfaces:

Serializable, RevisionHandler

Direct Known Subclasses:

AprioriItemSet, LabeledItemSet
```
public class ItemSet
extends Object
implements Serializable, RevisionHandler
```
Class for storing a set of items. Item sets are stored in a lexicographic order, which is determined by the header information of the set of instances used for generating the set of items. All methods in this class assume that item sets are stored in lexicographic order. The class provides the general methods used for item sets in class - and standard association rule mining.

Version:

$Revision$

Author:

Eibe Frank (eibe@cs.waikato.ac.nz)

See Also:

Serialized Form

Constructor Summary

Constructors
Constructor Description

ItemSet(int totalTrans)
Constructor

ItemSet(int[] array)
Contsructor

ItemSet(int totalTrans, int[] array)
Constructor

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`boolean`	`containedBy(Instance instance)`	Checks if an instance contains an item set.
`boolean`	`containedByTreatZeroAsMissing(Instance instance)`	Checks if an instance contains an item set.
`int`	`counter()`	Gets the counter
`static ArrayList<Object>`	`deleteItemSets(ArrayList<Object> itemSets, int minSupport, int maxSupport)`	Deletes all item sets that don't have minimum support.
`boolean`	`equals(Object itemSet)`	Tests if two item sets are equal.
`static Hashtable<ItemSet,Integer>`	`getHashtable(ArrayList<Object> itemSets, int initialSize)`	Return a hashtable filled with the given item sets.
`int[]`	`getItems()`	Get the item array
`String`	`getRevision()`	Returns the revision string.
`int`	`getTotalTransactions()`	Get the total number of transactions
`int`	`hashCode()`	Produces a hash code for a item set.
`int`	`itemAt(int k)`	Gest the index of the value of the specified attribute
`int[]`	`items()`	Gest the item set as an int array
`static ArrayList<Object>`	`mergeAllItemSets(ArrayList<Object> itemSets, int size, int totalTrans)`	Merges all item sets in the set of (k-1)-item sets to create the (k)-item sets and updates the counters.
`static ArrayList<Object>`	`pruneItemSets(ArrayList<Object> toPrune, Hashtable<ItemSet,Integer> kMinusOne)`	Prunes a set of (k)-item sets using the given (k-1)-item sets.
`static void`	`pruneRules(ArrayList<Object>[] rules, double minConfidence)`	Prunes a set of rules.
`void`	`setCounter(int count)`	Sets the counter
`void`	`setItem(int[] items)`	Sets an item sets
`void`	`setItemAt(int value, int k)`	Sets the index of an attribute value
`static ArrayList<Object>`	`singletons(Instances instances)`	Converts the header info of the given set of instances into a set of item sets (singletons).
`int`	`support()`	Outputs the support for an item set.
`String`	`toString(Instances instances)`	Returns the contents of an item set as a string.
`String`	`toString(Instances instances, char outerDelim, char innerDelim)`	Returns the contents of an item set as a delimited string.
`void`	`upDateCounter(Instance instance)`	Updates counter of item set with respect to given transaction.
`static void`	`upDateCounters(ArrayList<Object> itemSets, Instances instances)`	Updates counters for a set of item sets and a set of instances.
`static void`	`upDateCountersTreatZeroAsMissing(ArrayList<Object> itemSets, Instances instances)`	Updates counters for a set of item sets and a set of instances.
`void`	`updateCounterTreatZeroAsMissing(Instance instance)`	Updates counter of item set with respect to given transaction.

Methods inherited from class java.lang.Object
getClass, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - ItemSet
```
public ItemSet(int totalTrans)
```
    Constructor
    
    Parameters:
    
    totalTrans - the total number of transactions in the data
  - ItemSet
```
public ItemSet(int totalTrans,
               int[] array)
```
    Constructor
    
    Parameters:
    
    totalTrans - the total number of transactions in the data
    
    array - the attribute values encoded in an int array
  - ItemSet
```
public ItemSet(int[] array)
```
    Contsructor
    
    Parameters:
    
    array - the item set represented as an int array
- Method Detail
  - containedByTreatZeroAsMissing
```
public boolean containedByTreatZeroAsMissing(Instance instance)
```
    Checks if an instance contains an item set.
    
    Parameters:
    
    instance - the instance to be tested
    
    Returns:
    
    true if the given instance contains this item set
  - containedBy
```
public boolean containedBy(Instance instance)
```
    Checks if an instance contains an item set.
    
    Parameters:
    
    instance - the instance to be tested
    
    Returns:
    
    true if the given instance contains this item set
  - deleteItemSets
```
public static ArrayList<Object> deleteItemSets(ArrayList<Object> itemSets,
                                               int minSupport,
                                               int maxSupport)
                                        throws Exception
```
    Deletes all item sets that don't have minimum support.
    
    Parameters:
    
    maxSupport - the maximum support
    
    itemSets - the set of item sets to be pruned
    
    minSupport - the minimum number of transactions to be covered
    
    Returns:
    
    the reduced set of item sets
    
    Throws:
    
    Exception
  - equals
```
public boolean equals(Object itemSet)
```
    Tests if two item sets are equal.
    
    Overrides:
    
    equals in class Object
    
    Parameters:
    
    itemSet - another item set
    
    Returns:
    
    true if this item set contains the same items as the given one
  - getHashtable
```
public static Hashtable<ItemSet,Integer> getHashtable(ArrayList<Object> itemSets,
                                                            int initialSize)
                                                     throws Exception
```
    Return a hashtable filled with the given item sets.
    
    Parameters:
    
    itemSets - the set of item sets to be used for filling the hash table
    
    initialSize - the initial size of the hashtable
    
    Returns:
    
    the generated hashtable
    
    Throws:
    
    Exception
  - hashCode
```
public int hashCode()
```
    Produces a hash code for a item set.
    
    Overrides:
    
    hashCode in class Object
    
    Returns:
    
    a hash code for a set of items
  - mergeAllItemSets
```
public static ArrayList<Object> mergeAllItemSets(ArrayList<Object> itemSets,
                                                 int size,
                                                 int totalTrans)
                                          throws Exception
```
    Merges all item sets in the set of (k-1)-item sets to create the (k)-item sets and updates the counters.
    
    Parameters:
    
    totalTrans - thetotal number of transactions
    
    itemSets - the set of (k-1)-item sets
    
    size - the value of (k-1)
    
    Returns:
    
    the generated (k)-item sets
    
    Throws:
    
    Exception
  - pruneItemSets
```
public static ArrayList<Object> pruneItemSets(ArrayList<Object> toPrune,
                                              Hashtable<ItemSet,Integer> kMinusOne)
                                       throws Exception
```
    Prunes a set of (k)-item sets using the given (k-1)-item sets.
    
    Parameters:
    
    toPrune - the set of (k)-item sets to be pruned
    
    kMinusOne - the (k-1)-item sets to be used for pruning
    
    Returns:
    
    the pruned set of item sets
    
    Throws:
    
    Exception
  - pruneRules
```
public static void pruneRules(ArrayList<Object>[] rules,
                              double minConfidence)
                       throws Exception
```
    Prunes a set of rules.
    
    Parameters:
    
    rules - a two-dimensional array of lists of item sets. The first list of item sets contains the premises, the second one the consequences.
    
    minConfidence - the minimum confidence the rules have to have
    
    Throws:
    
    Exception
  - singletons
```
public static ArrayList<Object> singletons(Instances instances)
                                    throws Exception
```
    Converts the header info of the given set of instances into a set of item sets (singletons). The ordering of values in the header file determines the lexicographic order.
    
    Parameters:
    
    instances - the set of instances whose header info is to be used
    
    Returns:
    
    a set of item sets, each containing a single item
    
    Throws:
    
    Exception - if singletons can't be generated successfully
  - support
```
public int support()
```
    Outputs the support for an item set.
    
    Returns:
    
    the support
  - toString
```
public String toString(Instances instances)
```
    Returns the contents of an item set as a string.
    
    Parameters:
    
    instances - contains the relevant header information
    
    Returns:
    
    string describing the item set
  - toString
```
public String toString(Instances instances,
                       char outerDelim,
                       char innerDelim)
```
    Returns the contents of an item set as a delimited string.
    
    Parameters:
    
    instances - contains the relevant header information
    
    outerDelim - the outer delimiter
    
    innerDelim - the inner delimiter
    
    Returns:
    
    string describing the item set
  - upDateCounter
```
public void upDateCounter(Instance instance)
```
    Updates counter of item set with respect to given transaction.
    
    Parameters:
    
    instance - the instance to be used for ubdating the counter
  - updateCounterTreatZeroAsMissing
```
public void updateCounterTreatZeroAsMissing(Instance instance)
```
    Updates counter of item set with respect to given transaction.
    
    Parameters:
    
    instance - the instance to be used for ubdating the counter
  - upDateCounters
```
public static void upDateCounters(ArrayList<Object> itemSets,
                                  Instances instances)
                           throws Exception
```
    Updates counters for a set of item sets and a set of instances.
    
    Parameters:
    
    itemSets - the set of item sets which are to be updated
    
    instances - the instances to be used for updating the counters
    
    Throws:
    
    Exception
  - upDateCountersTreatZeroAsMissing
```
public static void upDateCountersTreatZeroAsMissing(ArrayList<Object> itemSets,
                                                    Instances instances)
                                             throws Exception
```
    Updates counters for a set of item sets and a set of instances.
    
    Parameters:
    
    itemSets - the set of item sets which are to be updated
    
    instances - the instances to be used for updating the counters
    
    Throws:
    
    Exception
  - counter
```
public int counter()
```
    Gets the counter
    
    Returns:
    
    the counter
  - items
```
public int[] items()
```
    Gest the item set as an int array
    
    Returns:
    
    int array represneting an item set
  - itemAt
```
public int itemAt(int k)
```
    Gest the index of the value of the specified attribute
    
    Parameters:
    
    k - the attribute index
    
    Returns:
    
    the index of the attribute value
  - setCounter
```
public void setCounter(int count)
```
    Sets the counter
    
    Parameters:
    
    count - the counter
  - setItem
```
public void setItem(int[] items)
```
    Sets an item sets
    
    Parameters:
    
    items - an int array representing an item set
  - setItemAt
```
public void setItemAt(int value,
                      int k)
```
    Sets the index of an attribute value
    
    Parameters:
    
    value - the inex of the attribute value
    
    k - the index of the attribute
  - getItems
```
public int[] getItems()
```
    Get the item array
    
    Returns:
    
    the item array
  - getTotalTransactions
```
public int getTotalTransactions()
```
    Get the total number of transactions
    
    Returns:
    
    the total number of transactions
  - getRevision
```
public String getRevision()
```
    Returns the revision string.
    
    Specified by:
    
    getRevision in interface RevisionHandler
    
    Returns:
    
    the revision

Constructor	Description
`ItemSet(int totalTrans)`	Constructor
`ItemSet(int[] array)`	Contsructor
`ItemSet(int totalTrans, int[] array)`	Constructor

Class ItemSet

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

ItemSet

ItemSet

ItemSet

Method Detail

containedByTreatZeroAsMissing

containedBy

deleteItemSets

equals

getHashtable

hashCode

mergeAllItemSets

pruneItemSets

pruneRules

singletons

support

toString

toString

upDateCounter

updateCounterTreatZeroAsMissing

upDateCounters

upDateCountersTreatZeroAsMissing

counter

items

itemAt

setCounter

setItem

setItemAt

getItems

getTotalTransactions

getRevision