private static int[] Calculeaza_vecini_LSH(int k, int id_user)
{
// Extragem din DB un Dictionary de toate id utilizator, lista de preparate
// comandate.
Dictionary<int, List<int>> toatePrep = DatabaseFunctions.
preparateComandateDupaUtilizator();
Dictionary<int, HashSet<int>> signatures = new Dictionary<int, HashSet<int>>();
HashSet<int> single_signatures = new HashSet<int>();
foreach (KeyValuePair<int, List<int>> entry in toatePrep)
{
signatures.Add(entry.Key, entry.Value.ToHashSet<int>());
single_signatures.UnionWith(entry.Value);
}
int numSets = signatures.Count;
int numHashFunctions = single_signatures.Count;
MinHash<int> minHash = new MinHash<int>(numHashFunctions);
int[][] minHashValues = minHash.initializeHashBuckets(numSets,
numHashFunctions);
int index = 0, index_cautat = 0;
List<HashSet<int>> list_signatures = new List<HashSet<int>>();
foreach(var entry in signatures)
{
minHash.computeMinHashForSet(entry.Value, index, minHashValues,
single_signatures);
if(entry.Key == id_user)
{
index_cautat = index;
}
index++;
list_signatures.Add(entry.Value);
}
LSH<int> lsh = new LSH<int>(minHashValues, list_signatures);
Dictionary<int, double> closeSimilarItems = lsh.closestSimilarItems(index_cautat, minHash);
int poz = 0;
int[] vecini = new int[k];
Dictionary<int, double> results = new Dictionary<int,double>();
int i = 0;
foreach(var closeItem in closeSimilarItems)
{
poz = closeItem.Key;
i = 0;
foreach (var entry in signatures)
{
if (i == poz)
{
results.Add(entry.Key, closeItem.Value);
break;
}
i++;
}
}
if (results.Count() > 0)
{
for (int ind = 0; ind < k; ind++)
{
vecini[ind] = results.MaxBy(x => x.Value).Key;
results.Remove(vecini[ind]);
if (results.Count == 0) break;
}
}
return vecini;
}