libSpatialIndex:在磁盘上加载/存储索引

libSpatialIndex: loading/storing index on disk

本文关键字：存储 索引 加载 磁盘 libSpatialIndex      更新时间：2023-10-16

我有一堆点，我需要对它们进行最近邻居搜索，所以我使用libSpatialIndex。代码非常直接，库让我可以选择将数据存储在磁盘上，但我无法加载它

代码：

int main(){
Tools::PropertySet* ps = GetDefaults();
Tools::Variant var;
// set index type to R*-Tree
var.m_varType = Tools::VT_ULONG;
var.m_val.ulVal = RT_RTree;
ps->setProperty("IndexType", var);
// Set index to store in disk
var.m_varType = Tools::VT_ULONG;
var.m_val.ulVal = RT_Disk;
ps->setProperty("IndexStorageType", var);
char filename[] = "indexTeste";
var.m_varType = Tools::VT_PCHAR;
var.m_val.pcVal = filename;
ps->setProperty("FileName", var);
var.m_varType = Tools::VT_BOOL;
var.m_val.blVal = false;
ps->setProperty("Overwrite", var);
cout << (*ps) << endl;
// initalise index
idx = new Index(*ps);
delete ps;
// Now there's specific code for point loading so I've shortened it - this part is working
for (...) { // all points
double pt[] = {point.getX(), point.getY()};
SpatialIndex::IShape* shape = 0;
shape = new SpatialIndex::Point(pt, 2);
// insert into index along with the an object and an ID
idx->index().insertData(nDataLength,(unsigned char*)&lineID,*shape,id);
}
// Now the search - working as well
ObjVisitor* visitor = new ObjVisitor;
SpatialIndex::Point* r = new SpatialIndex::Point(inter, 2);
idx->index().nearestNeighborQuery(1,*r,*visitor);
int64_t nResultCount;
nResultCount = visitor->GetResultCount();
// get actual results
vector<SpatialIndex::IData*>& results = visitor->GetResults();
SpatialIndex::IShape* shape;
results[0]->getShape(&shape);
unsigned char * dataAddr;
unsigned int length = sizeof(int);
results[0]->getData(length,&dataAddr);
int lineId = ((int*)dataAddr)[0];
SpatialIndex::Point center;
shape->getCenter(center);
}

然后程序就结束了。内存中确实创建了两个文件，"indexTest.dat"8.8MB和"indexTest.idx"0kB，但如果我在初始化后立即进行查询或检查索引中的元素数量，则会失败，并且树上只有一个节点。

我已经看了这些问题：（重新）加载带有spatialindex库的R树

C++空间索引库：从磁盘加载/存储主内存RTree

但我没有成功，因为我使用了Index，当我直接使用RTree时，数据插入速度慢了1000倍。

我找到了解决方案。索引实例化了树的ID，必须在创建索引时使用该ID才能正确加载文件。

代码：

//Example 
// When storing
Tools::PropertySet* ps = GetDefaults();
Index* idx;
idx = new Index(*ps);
Tools::PropertySet properties = idx->GetProperties();
Tools::Variant vari = properties.getProperty("IndexIdentifier");
cout << "ID: " << vari.m_val.llVal << endl;
// when loading
Tools::PropertySet* ps = GetDefaults();
Tools::Variant var;
// Important
var.m_varType = Tools::VT_BOOL;
var.m_val.blVal = false;
ps->setProperty("Overwrite", var);
var.m_varType = Tools::VT_LONGLONG;
var.m_val.llVal = ID; // The number "couted" before 
ps->setProperty("IndexIdentifier", var);
Index* idx;
idx = new Index(*ps);
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