void RecurseMining(List <DFSLevelItem> levelItems, int support, int minLength, int maxLength, MineResults mineResult)
{
// Simple pattern cut-off: if the pattern is not long enough, or too long
for (int i = levelItems.Count - 1; i >= 0; i--)
{
if (levelItems[i].Head.Count >= maxLength)
{
levelItems.RemoveAt(i);
continue;
}
if (levelItems[i].Head.Count + levelItems[i].Tail.Count < minLength)
{
levelItems.RemoveAt(i);
continue;
}
}
if (levelItems.Count == 0)
{
return;
}
Dictionary <int, int> lookAheadPrune = new Dictionary <int, int>();
for (int levelItemsLoop = 0; levelItemsLoop < levelItems.Count; levelItemsLoop++)
{
IntList tail = levelItems[levelItemsLoop].Tail;
ItemsetBasic head = levelItems[levelItemsLoop].Head;
List <FastSparseBitArray> bitArrays = new List <FastSparseBitArray>(tail.Count);
for (int loopTail = 0; loopTail < tail.Count; loopTail++)
{
int i = tail[loopTail];
FastSparseBitArray bitArray = null;
if (_dualComp != null)
{
ISimpleItemset dualItemset = _dualComp.GetItemset(head.GetLastItem(), i);
if (dualItemset == null)
{
tail.RemoveAt(loopTail);
loopTail--;
continue;
}
bitArray = dualItemset.GetTransactions();
}
else
{
bitArray = FastSparseBitArrayPool.Instance.Allocate();
_ds.BuildBitVector(head.GetLastItem(), i, bitArray);
}
if (head.Count > 1)
{
bitArray = bitArray.And(head.GetTransactions());
}
bitArray.frequency = bitArray.CountElements();
if (bitArray.frequency >= support)
{
bitArrays.Add(bitArray);
// Prune look-ahead
if (bitArray.frequency == head.support)
{
int lookAheadSupport;
if (lookAheadPrune.TryGetValue(i, out lookAheadSupport) == false)
{
lookAheadPrune.Add(i, bitArray.frequency);
}
else
{
lookAheadPrune[i] = Math.Max(lookAheadSupport, bitArray.frequency);
}
}
}
else
{
// Don't release bit vectors from O2 matrix, or there is no
// O2 matrix
if ((head.Count > 1) || (_dualComp == null))
{
FastSparseBitArrayPool.Instance.Release(bitArray);
}
tail.RemoveAt(loopTail);
loopTail--;
}
}
levelItems[levelItemsLoop].TailBitArrays = bitArrays;
}
for (int levelItemsLoop = 0; levelItemsLoop < levelItems.Count; levelItemsLoop++)
{
ItemsetBasic head = levelItems[levelItemsLoop].Head;
List <FastSparseBitArray> bitArrays = levelItems[levelItemsLoop].TailBitArrays;
int lookAheadSupport;
if (lookAheadPrune.TryGetValue(head.GetLastItem(), out lookAheadSupport) == true)
{
if (lookAheadSupport == head.support)
{
if (head.Count > 2)
{
for (int j = 0; j < bitArrays.Count; j++)
{
FastSparseBitArrayPool.Instance.Release(bitArrays[j]);
}
}
continue;
}
}
IntList tail = levelItems[levelItemsLoop].Tail;
List <DFSLevelItem> newLevelItems = new List <DFSLevelItem>();
for (int loopTail = 0; loopTail < tail.Count; loopTail++)
{
int i = tail[loopTail];
IntList newTail = (IntList)tail.Clone();
newTail.RemoveAt(loopTail);
ItemsetBasic newHead = new ItemsetBasic(head);
newHead.AddItem(i);
FastSparseBitArray bitArray = bitArrays[loopTail];
newHead.SetTransactions(bitArray);
newHead.support = bitArray.frequency;
if (newHead.Count >= minLength)
{
mineResult.Add(newHead);
}
newLevelItems.Add(new DFSLevelItem(newHead, newTail));
}
RecurseMining(newLevelItems, support, minLength, maxLength, mineResult);
// Release IntList
for (int j = 0; j < newLevelItems.Count; j++)
{
IntListPool.Instance.Release(newLevelItems[j].Tail);
}
// Release FastSparseBitArray
if (head.Count > 2)
{
for (int j = 0; j < bitArrays.Count; j++)
{
FastSparseBitArrayPool.Instance.Release(bitArrays[j]);
}
}
}
}
void RecurseMining(ItemsetBasic head, IntList tail, int support, int minLength, int maxLength, MineResults mineResult)
{
if (head.Count >= maxLength)
{
return;
}
if (head.Count + tail.Count < minLength)
{
return;
}
List <FastSparseBitArray> bitArrays = new List <FastSparseBitArray>(tail.Count);
for (int loopTail = 0; loopTail < tail.Count; loopTail++)
{
int i = tail[loopTail];
if (head.Count == 0)
{
IntList newTail = (IntList)tail.Clone(); // new IntList(tail);
newTail.RemoveAt(loopTail);
ItemsetBasic newHead = new ItemsetBasic(tail.Count);
newHead.AddItem(i);
RecurseMining(newHead, newTail, support, minLength, maxLength, mineResult);
IntListPool.Instance.Release(newTail);
}
else
{
FastSparseBitArray bitArray = null;
if (_dualComp != null)
{
ISimpleItemset dualItemset = _dualComp.GetItemset(head.GetLastItem(), i);
if (dualItemset == null)
{
tail.RemoveAt(loopTail);
loopTail--;
continue;
}
bitArray = dualItemset.GetTransactions();
}
else
{
bitArray = FastSparseBitArrayPool.Instance.Allocate();
_ds.BuildBitVector(head.GetLastItem(), i, bitArray);
}
if (head.Count > 1)
{
bitArray = bitArray.And(head.GetTransactions());
}
bitArray.frequency = bitArray.CountElements();
if (bitArray.frequency >= support)
{
bitArrays.Add(bitArray);
}
else
{
// Don't release bit vectors from O2 matrix, or there is no
// O2 matrix
if ((head.Count > 1) || (_dualComp == null))
{
FastSparseBitArrayPool.Instance.Release(bitArray);
}
tail.RemoveAt(loopTail);
loopTail--;
}
}
}
if (head.Count > 0)
{
for (int loopTail = 0; loopTail < tail.Count; loopTail++)
{
int i = tail[loopTail];
IntList newTail = (IntList)tail.Clone(); // new IntList(tail);
newTail.RemoveAt(loopTail);
// Create 'head' restore point
FastSparseBitArray restoreBitArray = head.GetTransactions();
int restoreSupport = head.support;
head.AddItem(i);
FastSparseBitArray bitArray = bitArrays[loopTail];
head.SetTransactions(bitArray);
head.support = bitArray.frequency;
RecurseMining(head, newTail, support, minLength, maxLength, mineResult);
IntListPool.Instance.Release(newTail);
if (head.Count >= minLength)
{
mineResult.Add(head);
}
head.SetTransactions(null);
if (head.Count > 2)
{
FastSparseBitArrayPool.Instance.Release(bitArray);
}
// Restore 'head'
head.RemoveLastItem();
head.SetTransactions(restoreBitArray);
head.support = restoreSupport;
}
}
}
