double compute(
int premiseSupport, int consequenceSupport, int totalSupport, int totalTransactions) {
double confidence =
METRIC_TYPE.CONFIDENCE.compute(
premiseSupport, consequenceSupport, totalSupport, totalTransactions);
return confidence / ((double) consequenceSupport / (double) totalTransactions);
}
/**
* Class for storing and manipulating an association rule.
*
* @author Mark Hall (mhall{[at]}pentaho{[dot]}com).
*/
public class DefaultAssociationRule extends AssociationRule implements Serializable {
/** For serialization */
private static final long serialVersionUID = -661269018702294489L;
/** Enum for holding different metric types */
public static enum METRIC_TYPE {
CONFIDENCE("conf") {
double compute(
int premiseSupport, int consequenceSupport, int totalSupport, int totalTransactions) {
return (double) totalSupport / (double) premiseSupport;
}
},
LIFT("lift") {
double compute(
int premiseSupport, int consequenceSupport, int totalSupport, int totalTransactions) {
double confidence =
METRIC_TYPE.CONFIDENCE.compute(
premiseSupport, consequenceSupport, totalSupport, totalTransactions);
return confidence / ((double) consequenceSupport / (double) totalTransactions);
}
},
LEVERAGE("lev") {
double compute(
int premiseSupport, int consequenceSupport, int totalSupport, int totalTransactions) {
double coverageForItemSet = (double) totalSupport / (double) totalTransactions;
double expectedCoverageIfIndependent =
((double) premiseSupport / (double) totalTransactions)
* ((double) consequenceSupport / (double) totalTransactions);
return coverageForItemSet - expectedCoverageIfIndependent;
}
},
CONVICTION("conv") {
double compute(
int premiseSupport, int consequenceSupport, int totalSupport, int totalTransactions) {
double num =
(double) premiseSupport
* (double) (totalTransactions - consequenceSupport)
/ (double) totalTransactions;
double denom = premiseSupport - totalSupport + 1;
return num / denom;
}
};
private final String m_stringVal;
METRIC_TYPE(String name) {
m_stringVal = name;
}
abstract double compute(
int premiseSupport, int consequenceSupport, int totalSupport, int totalTransactions);
public String toString() {
return m_stringVal;
}
public String toStringMetric(
int premiseSupport, int consequenceSupport, int totalSupport, int totalTransactions) {
return m_stringVal
+ ":("
+ Utils.doubleToString(
compute(premiseSupport, consequenceSupport, totalSupport, totalTransactions), 2)
+ ")";
}
public String toXML(
int premiseSupport, int consequenceSupport, int totalSupport, int totalTransactions) {
String result =
"<CRITERE name=\""
+ m_stringVal
+ "\" value=\" "
+ Utils.doubleToString(
compute(premiseSupport, consequenceSupport, totalSupport, totalTransactions), 2)
+ "\"/>";
return result;
}
}
/** Tags for display in the GUI */
public static final Tag[] TAGS_SELECTION = {
new Tag(METRIC_TYPE.CONFIDENCE.ordinal(), "Confidence"),
new Tag(METRIC_TYPE.LIFT.ordinal(), "Lift"),
new Tag(METRIC_TYPE.LEVERAGE.ordinal(), "Leverage"),
new Tag(METRIC_TYPE.CONVICTION.ordinal(), "Conviction")
};
/** The metric type for this rule */
protected DefaultAssociationRule.METRIC_TYPE m_metricType = METRIC_TYPE.CONFIDENCE;
/** The premise of the rule */
protected Collection<Item> m_premise;
/** The consequence of the rule */
protected Collection<Item> m_consequence;
/** The support for the premise */
protected int m_premiseSupport;
/** The support for the consequence */
protected int m_consequenceSupport;
/** The total support for the item set (premise + consequence) */
protected int m_totalSupport;
/** The total number of transactions in the data */
protected int m_totalTransactions;
/**
* Construct a new default association rule.
*
* @param premise the premise of the rule
* @param consequence the consequence of the rule
* @param metric the metric for the rule
* @param premiseSupport the support of the premise
* @param consequenceSupport the support of the consequence
* @param totalSupport the total support of the rule
* @param totalTransactions the number of transactions in the data
*/
public DefaultAssociationRule(
Collection<Item> premise,
Collection<Item> consequence,
METRIC_TYPE metric,
int premiseSupport,
int consequenceSupport,
int totalSupport,
int totalTransactions) {
m_premise = premise;
m_consequence = consequence;
m_metricType = metric;
m_premiseSupport = premiseSupport;
m_consequenceSupport = consequenceSupport;
m_totalSupport = totalSupport;
m_totalTransactions = totalTransactions;
}
/* (non-Javadoc)
* @see weka.associations.AssociationRule#getPremise()
*/
public Collection<Item> getPremise() {
return m_premise;
}
/* (non-Javadoc)
* @see weka.associations.AssociationRule#getConsequence()
*/
public Collection<Item> getConsequence() {
return m_consequence;
}
/* (non-Javadoc)
* @see weka.associations.AssociationRule#getPrimaryMetricName()
*/
public String getPrimaryMetricName() {
return TAGS_SELECTION[m_metricType.ordinal()].getReadable();
}
/* (non-Javadoc)
* @see weka.associations.AssociationRule#getPrimaryMetricValue()
*/
public double getPrimaryMetricValue() {
return m_metricType.compute(
m_premiseSupport, m_consequenceSupport, m_totalSupport, m_totalTransactions);
}
/* (non-Javadoc)
* @see weka.associations.AssociationRule#getNamedMetricValue(java.lang.String)
*/
public double getNamedMetricValue(String metricName) throws Exception {
DefaultAssociationRule.METRIC_TYPE requested = null;
for (DefaultAssociationRule.METRIC_TYPE m : METRIC_TYPE.values()) {
if (TAGS_SELECTION[m.ordinal()].getReadable().equals(metricName)) {
requested = m;
}
}
if (requested == null) {
throw new Exception("[AssociationRule] Unknown metric: " + metricName);
}
return requested.compute(
m_premiseSupport, m_consequenceSupport, m_totalSupport, m_totalTransactions);
}
/* (non-Javadoc)
* @see weka.associations.AssociationRule#getNumberOfMetricsForRule()
*/
public int getNumberOfMetricsForRule() {
return METRIC_TYPE.values().length;
}
/* (non-Javadoc)
* @see weka.associations.AssociationRule#getMetricNamesForRule()
*/
public String[] getMetricNamesForRule() {
String[] metricNames = new String[TAGS_SELECTION.length];
for (int i = 0; i < TAGS_SELECTION.length; i++) {
metricNames[i] = TAGS_SELECTION[i].getReadable();
}
return metricNames;
}
/* (non-Javadoc)
* @see weka.associations.AssociationRule#getMetricValuesForRule()
*/
public double[] getMetricValuesForRule() throws Exception {
double[] values = new double[TAGS_SELECTION.length];
for (int i = 0; i < TAGS_SELECTION.length; i++) {
values[i] = getNamedMetricValue(TAGS_SELECTION[i].getReadable());
}
return values;
}
/* (non-Javadoc)
* @see weka.associations.AssociationRule#getPremiseSupport()
*/
public int getPremiseSupport() {
return m_premiseSupport;
}
/* (non-Javadoc)
* @see weka.associations.AssociationRule#getConsequenceSupport()
*/
public int getConsequenceSupport() {
return m_consequenceSupport;
}
/* (non-Javadoc)
* @see weka.associations.AssociationRule#getTotalSupport()
*/
public int getTotalSupport() {
return m_totalSupport;
}
/* (non-Javadoc)
* @see weka.associations.AssociationRule#getTotalTransactions()
*/
public int getTotalTransactions() {
return m_totalTransactions;
}
/**
* Get a textual description of this rule.
*
* @return a textual description of this rule.
*/
public String toString() {
StringBuffer result = new StringBuffer();
result.append(
m_premise.toString()
+ ": "
+ m_premiseSupport
+ " ==> "
+ m_consequence.toString()
+ ": "
+ m_totalSupport
+ " ");
for (DefaultAssociationRule.METRIC_TYPE m : METRIC_TYPE.values()) {
if (m.equals(m_metricType)) {
result.append(
"<"
+ m.toStringMetric(
m_premiseSupport, m_consequenceSupport, m_totalSupport, m_totalTransactions)
+ "> ");
} else {
result.append(
""
+ m.toStringMetric(
m_premiseSupport, m_consequenceSupport, m_totalSupport, m_totalTransactions)
+ " ");
}
}
return result.toString();
}
}
