public static ItemsetCollection DoApriori(ItemsetCollection db, double supportThreshold)
{
Itemset I = db.GetUniqueItems();
ItemsetCollection L = new ItemsetCollection(); //resultant large itemsets
ItemsetCollection Li = new ItemsetCollection(); //large itemset in each iteration
ItemsetCollection Ci = new ItemsetCollection(); //pruned itemset in each iteration
//first iteration (1-item itemsets)
foreach (int item in I)
{
Ci.Add(new Itemset()
{
item
});
}
//next iterations
int k = 2;
while (Ci.Count != 0)
{
//set Li from Ci (pruning)
Li.Clear();
foreach (Itemset itemset in Ci)
{
itemset.Support = db.FindSupport(itemset);
if (itemset.Support >= supportThreshold)
{
Li.Add(itemset);
L.Add(itemset);
}
}
//set Ci for next iteration (find supersets of Li)
Ci.Clear();
Ci.AddRange(Bit.FindSubsets(Li.GetUniqueItems(), k)); //get k-item subsets
k += 1;
}
return(L);
}
public static ItemsetCollection DoAprioriNew(ItemsetCollection db, double supportThreshold)
{
//Itemset I = db.GetUniqueItems();
ItemsetCollection Fre = new ItemsetCollection(); //List of Items > support
ItemsetCollection L = new ItemsetCollection(); //resultant large itemsets
ItemsetCollection T = new ItemsetCollection(); //frequent items
//item > support
Itemset I = db.GetUniqueItems();
foreach (int item in I)
{
Itemset itemset = new Itemset()
{
item
};
itemset.Support = db.FindSupport(itemset);
if (itemset.Support >= supportThreshold)
{
Fre.Add(itemset);
}
}
ItemsetCollection subsets = Bit.FindSubsets(Fre.GetUniqueItems(), 0); //get all subsets
//Dictionary<Itemset, int> subsetsDic = subsets.Select((x, i) => new {x = x, i = 0 }).ToDictionary(k => k.x,k=>k.i);
//frequent items
foreach (Itemset itemdata in db)
{
Itemset itemset = new Itemset();
foreach (Itemset itemFre in Fre)
{
if (itemdata.Contains(itemFre[0]))
{
itemset.Add(itemFre[0]);
}
}
if (itemset.Count > 0)
{
T.Add(itemset);
foreach (Itemset items in subsets)
{
if (itemset.Contains(items))
{
items.Support++;
}
}
}
}
foreach (Itemset items in subsets)
{
if (items.Count > 0)
{
items.Support = (items.Support / (double)db.Count) * 100.0;
if (items.Support >= supportThreshold)
{
L.Add(items);
}
}
}
return(L);
}
public static ItemsetCollection DoFPGrowthParallel(ItemsetCollection db, double supportThreshold)
{
ItemsetCollection Fre = new ItemsetCollection(); //List of Items > support
ItemsetCollection T = new ItemsetCollection(); //frequent items
List <ItemsetCollection> P = new List <ItemsetCollection>();
ItemsetCollection FPTreeCon = new ItemsetCollection(); //Conditional FP-Tree
//item > support
//Itemset I = db.GetUniqueItems();
//foreach (string item in I)
//{
// Itemset itemset = new Itemset() { item };
// itemset.Support = db.FindSupport(itemset);
// if (itemset.Support >= supportThreshold)
// {
// Fre.Add(itemset);
// }
//}
//// sort item
//Fre.Sort(delegate (Itemset x, Itemset y)
//{
// if (x.Support > y.Support) return -1;
// else if (x.Support < y.Support)
// return 1;
// else return 0;
//});
////Fre = ParallelFre(db, supportThreshold);
////frequent items
//foreach (Itemset itemdata in db)
//{
// Itemset itemset = new Itemset();
// foreach (Itemset itemFre in Fre)
// {
// if (itemdata.Contains(itemFre[0]))
// {
// itemset.Add(itemFre[0]);
// }
// }
// T.Add(itemset);
//}
T = ParallelFPGrowth(db, supportThreshold, ref Fre);
// create FP Tree
FPTree tree = CreateTree(T);
// Conditional Patern Bases
foreach (Itemset itemset in Fre)
{
ItemsetCollection itemsetCollection = new ItemsetCollection();
for (int j = 0; j < tree.countNode; j++)
{
var node = tree.arrayNode[j];
if (node.itemName.Equals(itemset[0]) && !node.visited)
{
node.visited = true;
var nodeparent = node.nodeParent;
while (nodeparent.itemName > -1)
{
int index = itemsetCollection.FindIndex(nodeparent.itemName);
if (index > -1)
{
itemsetCollection[index].Support += node.count;
}
else
{
Itemset item = new Itemset();
item.Support = node.count;
item.Add(nodeparent.itemName);
itemsetCollection.Add(item);
}
nodeparent = nodeparent.nodeParent;
}
}
}
P.Add(itemsetCollection);
}
// Conditional FP-Tree
for (int i = 0; i < P.Count; i++)
{
ItemsetCollection itemsetCollection = new ItemsetCollection();
//itemsetCollection.Add(Fre[i]); //hoán vị sau
foreach (var item in P[i])
{
if (db.Support(item) >= supportThreshold)
{
itemsetCollection.Add(item);
}
}
ItemsetCollection subsets = Bit.FindSubsets(itemsetCollection.GetUniqueItems(), 0); //get all subsets
foreach (Itemset items in subsets)
{
items.Add(Fre[i][0]);
items.Support = db.FindSupport(items);
if (items.Support >= supportThreshold)
{
FPTreeCon.Add(items);
}
}
}
return(FPTreeCon);
}
