public EstimateResult compare(IEnumerable<Vertex> vertices, SnifferWifiMeasurement measurement)
{
measurement = getNStrongestAPMeasurement(measurement, 7);
if (vertices == null || measurement == null)
return null;
bcs = WifiPosEngine.BestCandidateSet; //new BCS(5); //bcs.clear();
double curDist; //distance of current vertice in search space
EstimateResult result = new EstimateResult(null, double.MaxValue);
foreach (Vertex curVertex in vertices) //sammenlign med hver Vertex
{
foreach (SnifferWifiMeasurement curFP in curVertex.SnifferWifiMeasurements) //sammenlign med hvert fingerprint (usually only one - otherwise use more intelligent approach)
{
curDist = 0;
foreach (String mac in measurement.getMACs()) //all APs in sample
if (curFP.containsMac(mac))
curDist += Math.Pow((measurement.getAvgDbM(mac) - curFP.getAvgDbM(mac)), 2);
else
curDist += Math.Pow((measurement.getAvgDbM(mac) - MISSING_MAC_PENALTY), 2);
curDist = Math.Sqrt(curDist);
if (curDist < result.getDistance())
{
result.setDistance(curDist);
result.setVertex(curVertex);
}
bcs.add(curVertex, curDist); //add to best candidate set - which will take care of only using the best estimates.
}
}
//The following only yields a local error estimate within the primary- or secondary
//vertices and may thus not be appropriate
result.setErrorEstimate(Math.Ceiling(bcs.getMaxDistance()));
return result;
}
//Public visibility so we can test it (directly) via unit tests
public static SnifferWifiMeasurement getNStrongestAPMeasurement(SnifferWifiMeasurement measurement, int n)
{
if (measurement.getMACs().Count < n)
return measurement;
SortedDictionary<double, String> strongestAPs = new SortedDictionary<double, String>();
//Find the n strongest macs
//
foreach (String mac in measurement.getMACs()) //all APs in sample
{
double curMacVal = measurement.getAvgDbM(mac);
while (strongestAPs.ContainsKey(curMacVal))
curMacVal += 0.0001;
strongestAPs.Add(curMacVal, mac);
//NB: TreeMap sorts members in ascending order!
//Thus, we remove from the head to keep the strongest values
if (strongestAPs.Count > n)
strongestAPs.Remove(strongestAPs.First().Key);
}
//Create new measurement containing n strongest macs
SnifferWifiMeasurement result = new SnifferWifiMeasurement();
foreach (double d in strongestAPs.Keys)
{
SnifferHistogram h = new SnifferHistogram();
h.Mac = strongestAPs[d];
h.value = (int)d;
h.count = 1;
result.SnifferHistograms.Add(h);
//result.addValue(strongestAPs.get(d), (int)d);
}
return result;
}