public LocalitySensitiveHashing(double minSim, double maxSim, double minProb, double maxProb)
{
int hashesInGroup = -1;
var k = Math.Log(1.0 - minProb) / Math.Log(1.0 - maxProb);
double oldFn, fn = 1.0;
for (int tr = 1; tr < 40; tr++)
{
oldFn = fn;
fn = (Math.Log(1.0 - Math.Pow(minSim, tr)) / Math.Log(1.0 - Math.Pow(maxSim, tr))) - k;
if (tr == 1)
{
continue;
}
if (fn > 0)
{
continue;
}
hashesInGroup = -fn > oldFn ? tr - 1 : tr;
break;
}
if (hashesInGroup == -1)
{
throw new ArgumentException();
}
//
double groupCount = Math.Log(1.0 - maxProb) / Math.Log(1.0 - Math.Pow(maxSim, hashesInGroup));
//
_hashesInGroup = hashesInGroup;
_groupCount = (int)(groupCount + 0.9999);
//
_hashing = new MinHashing(_hashesInGroup * _groupCount);
}
public LocalitySensitiveHashing(int hashesInGroup, int groupCount)
{
_hashesInGroup = hashesInGroup;
_groupCount = groupCount;
_hashing = new MinHashing(_hashesInGroup * _groupCount);
}
