public FPGrowth(List <Transaction> dataset, double support)
{
dataSet = dataset;
tree = new FPTree();
patterns = new List <ItemSet>();
minSupport = support;
}
public List <ItemSet> MinePatterns(Dictionary <string, int> supports, double support)
{
patterns = new List <ItemSet>();
foreach (var supp in supports) //add all frequent 1 item sets
{
patterns.Add(new ItemSet(new string[] { supp.Key }, supp.Value));
}
var _supp = supports.Keys.Reverse();
List <string> usedKeys = new List <string>();
foreach (string key in _supp)
{
usedKeys.Add(key);
List <ItemSet> freqByKey = new List <ItemSet>();
MinePatterns(rootNode, key, support, freqByKey);
Dictionary <string, double> FList = GenerateFList(freqByKey, key, support);
List <ItemSet> twoItemSets = new List <ItemSet>();
FList = FList.OrderByDescending(kv => kv.Value).Reverse().ToDictionary(kv => kv.Key, kv => kv.Value);
foreach (var kvpair in FList)
{
ItemSet its = new ItemSet(new string[] { key, kvpair.Key }, kvpair.Value); //add frequent 2 item sets containing string key
twoItemSets.Add(its);
patterns.Add(its);
}
FPTree subTree = BuildSubTree(freqByKey, key, support);
foreach (var twoItemSet in twoItemSets) //if more then 1 element in FLISt --> candidate 3+ ItemSet
{
string itskey = twoItemSet.Items.ToList()[1];
var itsval = twoItemSet.Support;
var subFreqByKey = new List <ItemSet>();
MinePatterns(subTree.rootNode, itskey, support, subFreqByKey);
var itsFList = GenerateFList(subFreqByKey, itskey, support);
var _FList = new Dictionary <string, double>(FList);
foreach (string k in usedKeys) //remove combinations where keys are already used so there's no duplicates
{
if (itsFList.ContainsKey(k))
{
itsFList.Remove(k);
}
}
MineLonger(twoItemSet.Items, support, itsFList, subFreqByKey); // Mine longer sets containing this 2 item set (recursive)
}
}
return(patterns.Where(p => p.Items.Count() > 0).ToList());
}
void MineLonger(IEnumerable <string> previous, double minSupport, Dictionary <string, double> subFList, List <ItemSet> SubFreqKey)
{
foreach (var kvpair in subFList.Reverse())
{
var items = previous.ToList();
items.Add(kvpair.Key); // add all (n+1)-itemsets containing previous and where n = previous.Count
ItemSet its = new ItemSet(items, kvpair.Value);
if (its.Support >= minSupport)
{
patterns.Add(its);
}
}
foreach (var kvpair in subFList.Reverse())
{
var items = previous.ToList();
items.Add(kvpair.Key);
List <ItemSet> subFreqByKey = new List <ItemSet>();
FPTree subsubTree = BuildSubTree(SubFreqKey, items[items.Count - 2], minSupport);
MinePatterns(subsubTree.rootNode, kvpair.Key, minSupport, subFreqByKey);
var _subFList = GenerateFList(subFreqByKey, kvpair.Key, minSupport); //create new FList for newly added pattern
MineLonger(items, minSupport, _subFList, subFreqByKey);
}
}
