void
MT::CollectStats ()
{
GiSTpath path;
path.MakeRoot ();
GiSTnode *node = ReadNode (path);
if (!node->IsLeaf()) {
int maxLevel = node->Level();
double *radii = new double[maxLevel];
int *pages = new int[maxLevel];
for (int i=0; i<maxLevel; i++) {
pages[i] = 0;
radii[i] = 0;
}
TruePredicate truePredicate;
GiSTlist<GiSTentry*> list = node->Search(truePredicate); // retrieve all the entries in this node
double overlap = ((MTnode *)node)->Overlap();
double totalOverlap = overlap;
delete node;
while (!list.IsEmpty()) {
GiSTentry *entry = list.RemoveFront ();
path.MakeChild (entry->Ptr());
node = ReadNode (path);
overlap = ((MTnode *)node)->Overlap();
totalOverlap += overlap;
pages[node->Level()]++;
radii[node->Level()] += ((MTkey *) entry->Key())->MaxRadius();
GiSTlist<GiSTentry*> newlist;
if (!node->IsLeaf()) {
newlist = node->Search(truePredicate); // recurse to next level
}
while (!newlist.IsEmpty()) {
list.Append (newlist.RemoveFront ());
}
path.MakeParent ();
delete entry;
delete node;
}
// output the results
cout << "Level:\tPages:\tAverage_Radius:"<<endl;
int totalPages = 1; // for the root
for (int i=maxLevel-1; i>=0; i--) {
totalPages += pages[i];
cout << i << ":\t" << pages[i] << "\t" << radii[i]/pages[i] << endl;
}
cout << "TotalPages:\t" << totalPages << endl;
cout << "LeafPages:\t" << pages[0] << endl;
cout << "TotalOverlap:\t" << (float)totalOverlap << endl;
delete []radii;
delete []pages;
} else {
delete node;
}
}
// return root level+1 (the height of the tree)
// this is used in the "splitting" phase of the BulkLoad algorithm
int
MT::TreeHeight () const
{
GiSTpath path;
path.MakeRoot ();
GiSTnode *root = ReadNode (path);
int i = root->Level();
delete root;
return (i+1);
}
GiSTnode*
GiST::ChooseSubtree(GiSTpage page, const GiSTentry &entry, int level)
{
GiSTnode *node;
GiSTpath path;
for(;;) {
path.MakeChild(page);
node=ReadNode(path);
if(level==node->Level()||node->IsLeaf()) break;
page=node->SearchMinPenalty(entry);
delete node;
}
return node;
}
GiSTentry*
GiSTcursor::Next()
{
GiSTpage page;
while (first || !stack.IsEmpty()) {
if (first) {
page = GiSTRootPage;
first = 0;
} else {
assert(lastlevel >= 0);
GiSTentry *entry = stack.RemoveFront();
if (entry->IsLeaf())
return entry;
// Pop off the stack
for (int i=0; i < entry->Level() - lastlevel; i++)
path.MakeParent();
page = entry->Ptr();
delete entry;
}
// Entry was a pointer to another node
path.MakeChild(page);
GiSTnode *node = gist.ReadNode(path);
lastlevel = node->Level();
GiSTlist<GiSTentry*> list = node->Search(*query);
while (!list.IsEmpty()) {
GiSTentry *entry = list.RemoveRear();
stack.Prepend(entry);
}
delete node;
}
// The search is over...
return NULL;
}