Exemple #1
0
vector< vector<u32> > kmeans_pp(const vector< vector<f64> >& points, u32 k,
                                algo::iLCG& lcg,
                                      vector< vector<f64> >& centers)
{
    if (points.size() == 0)
        throw eInvalidArgument("There must be points to cluster!");
    if (points[0].size() == 0)
        throw eInvalidArgument("There must be at least one dimension!");
    for (size_t i = 1; i < points.size(); i++)
        if (points[i].size() != points[0].size())
            throw eInvalidArgument("All data points must have the same dimensionality.");
    if (k == 0)
        throw eInvalidArgument("Clustering into zero clusters makes no sense.");

    centers.resize(k);
    centers[0] = points[lcg.next() % points.size()];
    for (u32 i = 1; i < k; i++)
    {
        vector<f64> cumDists(points.size());
        for (size_t d = 0; d < cumDists.size(); d++)
        {
            f64 mind = s_distanceSquared(points[d], centers[0]);
            for (u32 j = 1; j < i; j++)
                mind = std::min(mind, s_distanceSquared(points[d], centers[j]));
            cumDists[d] = (d == 0) ? (mind) : (cumDists[d-1]+mind);
        }

        f64 ran = ((f64)lcg.next()) / ((f64)lcg.randMax()) * cumDists.back();
        size_t d;
        for (d = 0; ran > cumDists[d]; d++) { }
        centers[i] = points[d];
    }

    return kmeans(points, k, centers);
}
Exemple #2
0
static
vector<u8> s_genMessage(algo::iLCG& lcg)
{
    u32 len = (lcg.next() % kMaxMessageLen) + 1;
    vector<u8> mess(len);
    for (u32 i = 0; i < len; i++)
        mess[i] = (lcg.next() % 256);
    return mess;
}
Exemple #3
0
static
vector<f64> s_randPoint(algo::iLCG& lcg, f64 rmin, f64 rmax, u32 dimensions)
{
    vector<f64> v(dimensions);
    for (u32 i = 0; i < dimensions; i++)
    {
        v[i] = ((f64)lcg.next()) / ((f64)lcg.randMax());    // [0.0, 1.0]
        v[i] *= rmax-rmin;                                  // [0.0, rmax-rmin]
        v[i] += rmin;                                       // [rmin, rmax]
    }
    return v;
}