public static int[] InMemoryGet(float[][] data, int count, int Hdims, int seed, out int[] ids)
{
LSHTree instance = new LSHTree(data, count, Hdims, seed);
instance.InMemoryGet(0, data.Length);
ids = instance.ids;
return(instance.indicies);
}
public static List <int>[] Candidates(float[][] data, int k, LSHFConfiguration LSHFConfig, bool verbose = false)
{
Random SeedGen = LSHFConfig.LSHSeed == -1 ? new Random() : new Random(LSHFConfig.LSHSeed);
int N = data.Length;
int trees = LSHFConfig.LSHForestTrees;
List <int>[] candidates = new List <int> [N];
if (N < 2 * k)
{
for (int i = 0; i < N; i++)
{
candidates[i] = Enumerable.Range(0, N).ToList();
candidates[i].RemoveAt(i);
}
return(candidates);
}
for (int i = 0; i < N; i++)
{
candidates[i] = new List <int>(2 * k);
}
int[] seeds = new int[trees];
for (int i = 0; i < trees; i++)
{
seeds[i] = SeedGen.Next();
}
if (verbose)
{
Console.WriteLine("LSH Forest building {0} trees", trees);
}
Parallel.For(0, trees, i =>
{
int[] indicies = LSHTree.InMemoryGet(data, LSHFConfig.LSHTreeC * k / trees, LSHFConfig.LSHHashDims, seeds[i], out int[] cand);
for (int j = 0; j < N; j++)
{
lock (candidates[j])
for (int ii = indicies[2 * j]; ii < indicies[2 * j + 1]; ii++)
{
candidates[j].Add(cand[ii]);
}
}
});
Parallel.For(0, N, i =>
{
candidates[i].Sort();
int a = 0;
int b = 1;
while (b < candidates[i].Count)
{
if (candidates[i][b] == candidates[i][a])
{
b++;
}
else
{
candidates[i][++a] = candidates[i][b++];
}
}
a++;
candidates[i].RemoveRange(a, b - a);
candidates[i].Remove(i);
});
int fill = RandomFill(candidates, k, SeedGen.Next());
if (fill != 0)
{
Console.WriteLine("WARNING! Added {0} random candidates total in a LSH Forest.", fill);
}
return(candidates);
}
