/* Returns C(1), the candidate item sets with size 1 */
public ItemSetTable FindFirstCandidateItemSetTable()
{
ItemSetTable candidateItemSets = new ItemSetTable();
candidateItemSets.order = 1;
SortedSet <int> set = new SortedSet <int>();
foreach (Transaction t in this)
{
foreach (int item in t)
{
set.Add(item);
}
}
foreach (int item in set)
{
ItemSet itemSet = new ItemSet();
itemSet.Add(item);
candidateItemSets.Add(itemSet, 0);
}
IncrementCandidatesIn(candidateItemSets);
return(candidateItemSets);
}
/* Returns L(k+1), candidates in C(k+1) with min_support */
public ItemSetTable BuildFrequentItemSet()
{
int count = 0;
ItemSetTable frequentTable = new ItemSetTable(this.order);
ICollection <ItemSet> keys = new List <ItemSet>(this.Keys);
foreach (ItemSet itemSet in keys)
{
int support = this[itemSet];
if (support >= minSupport)
{
frequentTable.Add(itemSet, support);
++count;
}
}
// If no item set has higher support than min_support, return null.
if (count == 0)
{
return(null);
}
else
{
return(frequentTable);
}
}
/* Print all item sets in input item set table */
public static void Print(ItemSetTable ist)
{
if (ist != null)
{
Console.WriteLine("Order: {0}", ist.order);
Console.WriteLine(ist.ToString());
}
else
{
Console.WriteLine("don't exist");
}
}
/* Each candidates in input candidate item set table is incre
* */
public void IncrementCandidatesIn(ItemSetTable candidateTable)
{
foreach (Transaction t in this)
{
ICollection <ItemSet> keys = new List <ItemSet>(candidateTable.Keys);
foreach (ItemSet itemSet in keys)
{
if (t.IsSupersetOf(itemSet) == true)
{
candidateTable.Increment(itemSet);
}
}
}
}
/* Returns the candidates C(k+1) generated from L(k) */
public ItemSetTable BuildCandidateItemSet()
{
ItemSetTable candidateTable = new ItemSetTable(this.order + 1);
foreach (ItemSet I1 in this.Keys) // this = L(k)
{
foreach (ItemSet I2 in this.Keys)
{
ItemSet c = null;
IList <int> iList1 = new List <int>(I1);
IList <int> iList2 = new List <int>(I2);
bool joinCondition = false;
for (int i = 0; i < this.order; ++i)
{
// last element
if (i == this.order - 1)
{
if (iList1[i] < iList2[i])
{
joinCondition = true;
}
}
else
{
if (iList1[i] != iList2[i])
{
joinCondition = false;
break;
}
}
}
if (joinCondition == true)
{
c = ItemSet.UnionBetween(I1, I2); // join step: generate candidates
if (hasInfrequentSubSet(c) == false)
{
candidateTable.Add(c, 0);
}
}
}
}
return(candidateTable);
}
public static void Main(string[] args)
{
Console.WriteLine(DateTime.Now.ToString("O"));
string inputFile = null;
string outputFile = null;
int minSupPercent = 0;
int minSupport = 0;
if (args.Length != 3)
{
PrintUsage();
}
try
{
minSupPercent = Convert.ToInt32(args[0]);
inputFile = String.Copy(args[1]);
outputFile = String.Copy(args[2]);
// If input file don't exist, throw exception.
if (File.Exists(inputFile) == false)
{
throw new FileNotFoundException();
}
// If output file already exists, the file will be deleted.
if (File.Exists(outputFile) == true)
{
File.Delete(outputFile);
}
}
catch (Exception e)
{
Console.WriteLine(e);
PrintUsage();
}
TransactionDatabase database = new TransactionDatabase(inputFile, outputFile);
ItemSetTable candidateTable = new ItemSetTable();
ItemSetTable frequentTable = null;
/* Printing input arguments.. */
minSupport = minSupPercent * database.Count / 100;
Console.WriteLine("minimum support: {0} %", minSupPercent);
Console.WriteLine("minimum support: {0}", minSupport);
ItemSetTable.SetMinSupport(minSupport);
/* Build C(1), the candidate item sets with size 1 */
candidateTable = database.FindFirstCandidateItemSetTable();
/* Build L(1), the frequent item sets with size 1 */
if (candidateTable != null)
{
frequentTable = candidateTable.BuildFrequentItemSet();
}
for (int k = 1; frequentTable != null; ++k)
{
// C(k+1) = candidates generated from L(k)
candidateTable = frequentTable.BuildCandidateItemSet();
// for each transaction t in database do increment the count of
// all candidates in C(k+1) that are contained in t
database.IncrementCandidatesIn(candidateTable);
// L(k+1) = candidates in C(K+1) with min_support
frequentTable = candidateTable.BuildFrequentItemSet();
if (frequentTable != null)
{
foreach (ItemSet frequentItemSet in frequentTable.Keys)
{
database.FindAssociationRules(frequentItemSet);
}
}
}
Console.WriteLine("Finding Association Rules is finished.");
Console.WriteLine(DateTime.Now.ToString("O"));
}