| public Generate ( Descriptor descriptor, IEnumerable | ||
| descriptor | Descriptor | The descriptor. |
| examples | IEnumerable | The examples. |
| k | int | The int to process. |
| metric | IDistance | (Optional) the metric. |
| return | numl.Unsupervised.Cluster | |
public void Test_Feed_KMeans()
{
int groups = 4;
Feed[] feeds = Feed.GetData();
Descriptor descriptor = Descriptor.Create<Feed>();
KMeans kmeans = new KMeans();
kmeans.Descriptor = descriptor;
int[] grouping = kmeans.Generate(feeds, groups, new CosineDistance());
for (int i = 0; i < grouping.Length; i++)
feeds[i].Cluster = grouping[i];
}
public void Test_Object_KMeans(int size)
{
Matrix X = GenerateData(size);
var objects = X.GetRows()
.Select(v => new AB { A = v[0], B = v[1] })
.ToArray();
var descriptor = Descriptor.Create<AB>();
KMeans model = new KMeans();
var clusters = model.Generate(descriptor, objects, 2, new EuclidianDistance());
Assert.AreEqual(2, clusters.Children.Length);
Assert.AreEqual(size, clusters[0].Members.Length);
Assert.AreEqual(size, clusters[1].Members.Length);
}
public void Test_Numerical_KMeans(int size)
{
Matrix X = GenerateData(size);
KMeans model = new KMeans();
var assignment = model.Generate(X, 2, new EuclidianDistance());
Assert.AreEqual(size * 2, assignment.Length);
var a1 = assignment.First();
var a2 = assignment.Last();
for (int i = 0; i < size * 2; i++)
{
if (i < size)
Assert.AreEqual(a1, assignment[i]);
else
Assert.AreEqual(a2, assignment[i]);
}
}
/// <summary>Generates.</summary>
/// <param name="X">The Matrix to process.</param>
/// <param name="k">The int to process.</param>
public void Generate(Matrix X, int k)
{
int n = X.Rows;
int d = X.Cols;
/***********************
* initialize parameters
***********************/
// convergence params
var log_probability = 0d;
var probability_difference = double.MaxValue;
var mu_difference = double.MaxValue;
// initialize centers with KMeans
KMeans kmeans = new KMeans();
var asgn = kmeans.Generate(X, k, new EuclidianDistance());
// tentative centers
var mu_k = kmeans.Centers;
// initial covariances (stored as diag(cov) 1 of k)
var sg_k = new Matrix(k, d);
for (int i = 0; i < k; i++)
{
var indices = asgn.Select((a, b) => new Tuple<int, int>(a, b)).Where(t => t.Item1 == i).Select(t => t.Item2);
var matrix = X.Slice(indices, VectorType.Row);
sg_k[i] = matrix.CovarianceDiag();
}
// mixing coefficient
var pi_k = asgn
.OrderBy(i => i)
.GroupBy(j => j)
.Select(g => (double)g.Count() / (double)asgn.Length)
.ToVector();
int max_iter = 100;
do
{
/***********************
* Expectation Step
***********************/
// responsibilty matrix: how much is gaussian k responsible for this point x
var z_nk = new Matrix(n, k);
for (int i = 0; i < n; i++)
{
// pi_j * N(x_n | mu_j, sigma_j)
for (int j = 0; j < k; j++)
z_nk[i, j] = pi_k[j] * Normal(X[i], mu_k[j], sg_k[j]);
var dn = z_nk[i].Sum();
if(dn == 0)
Console.WriteLine("Uh oh....");
z_nk[i].Each(z => z / dn);
}
/***********************
* Maximization Step
***********************/
var N_k = z_nk.Sum(VectorType.Row);
var mu_k_new = new Matrix(mu_k.Rows, mu_k.Cols);
for (int i = 0; i < k; i++)
{
var sum = Vector.Zeros(d);
for (int j = 0; j < n; j++)
sum += z_nk[j, i] * X[j];
mu_k_new[i] = sum / N_k[i];
}
var sg_k_new = new Matrix(k, d);
for (int i = 0; i < k; i++)
{
var sum = Vector.Zeros(d);
for (int j = 0; j < n; j++)
sum += z_nk[j, i] * (X[j] - mu_k_new[i]).Each(s => s * s);
sg_k_new[i] = sum / N_k[i];
}
var pi_k_new = N_k / n;
/***********************
* Convergence Check
***********************/
var new_log_prob = 0d;
for (int i = 0; i < n; i++)
{
var acc = 0d;
// pi_j * N(x_n | mu_j, sigma_j)
for (int j = 0; j < k; j++)
acc += pi_k[j] * Normal(X[i], mu_k[j], sg_k[j]);
new_log_prob += System.Math.Log(acc, System.Math.E);
}
// log likelihood differences
probability_difference = System.Math.Abs(log_probability - new_log_prob);
Console.WriteLine("Log Likelihoods (Total Points: {0}, k={1}, d={2})\nO: {3}\nN: {4}\nDifference: {5}\n", n, k, d, log_probability, new_log_prob, probability_difference);
log_probability = new_log_prob;
// centers differences
mu_difference = mu_k.GetRows()
.Zip(mu_k_new.GetRows(), (v1, v2) => new { V1 = v1, V2 = v2 })
.Sum(a => (a.V1 - a.V2).Norm());
Console.WriteLine("Centers:\nO: {0}\nN: {1}\nDifference: {2}\n", mu_k, mu_k_new, mu_difference);
mu_k = mu_k_new;
// covariance differences
double diff = sg_k.GetRows()
.Zip(sg_k_new.GetRows(), (v1, v2) => new { V1 = v1, V2 = v2 })
.Sum(a => (a.V1 - a.V2).Norm());
Console.WriteLine("Covariance:\nO: {0}\nN: {1}\nDifference: {2}\n", sg_k, sg_k_new, diff);
sg_k = sg_k_new;
// mixing differences
diff = (pi_k - pi_k_new).Each(s => System.Math.Abs(s)).Sum();
Console.WriteLine("Mixing Coeffs:\nO: {0}\nN: {1}\nDifference: {2}\n", pi_k, pi_k_new, diff);
pi_k = pi_k_new;
Console.WriteLine("-------------------------------------------------------------");
} while (probability_difference > .0000000001 && mu_difference > .0000000001 && --max_iter >= 0);
}
/// <summary>Generates.</summary>
/// <param name="X">The Matrix to process.</param>
/// <param name="k">The int to process.</param>
public void Generate(Matrix X, int k)
{
int n = X.Rows;
int d = X.Cols;
/***********************
* initialize parameters
***********************/
// convergence params
var log_probability = 0d;
var probability_difference = double.MaxValue;
var mu_difference = double.MaxValue;
// initialize centers with KMeans
KMeans kmeans = new KMeans();
var asgn = kmeans.Generate(X, k, new EuclidianDistance());
// tentative centers
var mu_k = kmeans.Centers;
// initial covariances (stored as diag(cov) 1 of k)
var sg_k = new Matrix(k, d);
for (int i = 0; i < k; i++)
{
var indices = asgn.Select((a, b) => new Tuple <int, int>(a, b)).Where(t => t.Item1 == i).Select(t => t.Item2);
var matrix = X.Slice(indices, VectorType.Row);
sg_k[i] = matrix.CovarianceDiag();
}
// mixing coefficient
var pi_k = asgn
.OrderBy(i => i)
.GroupBy(j => j)
.Select(g => (double)g.Count() / (double)asgn.Length)
.ToVector();
int max_iter = 100;
do
{
/***********************
* Expectation Step
***********************/
// responsibilty matrix: how much is gaussian k responsible for this point x
var z_nk = new Matrix(n, k);
for (int i = 0; i < n; i++)
{
// pi_j * N(x_n | mu_j, sigma_j)
for (int j = 0; j < k; j++)
{
z_nk[i, j] = pi_k[j] * Normal(X[i], mu_k[j], sg_k[j]);
}
var dn = z_nk[i].Sum();
if (dn == 0)
{
Console.WriteLine("Uh oh....");
}
z_nk[i].Each(z => z / dn);
}
/***********************
* Maximization Step
***********************/
var N_k = z_nk.Sum(VectorType.Row);
var mu_k_new = new Matrix(mu_k.Rows, mu_k.Cols);
for (int i = 0; i < k; i++)
{
var sum = Vector.Zeros(d);
for (int j = 0; j < n; j++)
{
sum += z_nk[j, i] * X[j];
}
mu_k_new[i] = sum / N_k[i];
}
var sg_k_new = new Matrix(k, d);
for (int i = 0; i < k; i++)
{
var sum = Vector.Zeros(d);
for (int j = 0; j < n; j++)
{
sum += z_nk[j, i] * (X[j] - mu_k_new[i]).Each(s => s * s);
}
sg_k_new[i] = sum / N_k[i];
}
var pi_k_new = N_k / n;
/***********************
* Convergence Check
***********************/
var new_log_prob = 0d;
for (int i = 0; i < n; i++)
{
var acc = 0d;
// pi_j * N(x_n | mu_j, sigma_j)
for (int j = 0; j < k; j++)
{
acc += pi_k[j] * Normal(X[i], mu_k[j], sg_k[j]);
}
new_log_prob += System.Math.Log(acc, System.Math.E);
}
// log likelihood differences
probability_difference = System.Math.Abs(log_probability - new_log_prob);
Console.WriteLine("Log Likelihoods (Total Points: {0}, k={1}, d={2})\nO: {3}\nN: {4}\nDifference: {5}\n", n, k, d, log_probability, new_log_prob, probability_difference);
log_probability = new_log_prob;
// centers differences
mu_difference = mu_k.GetRows()
.Zip(mu_k_new.GetRows(), (v1, v2) => new { V1 = v1, V2 = v2 })
.Sum(a => (a.V1 - a.V2).Norm());
Console.WriteLine("Centers:\nO: {0}\nN: {1}\nDifference: {2}\n", mu_k, mu_k_new, mu_difference);
mu_k = mu_k_new;
// covariance differences
double diff = sg_k.GetRows()
.Zip(sg_k_new.GetRows(), (v1, v2) => new { V1 = v1, V2 = v2 })
.Sum(a => (a.V1 - a.V2).Norm());
Console.WriteLine("Covariance:\nO: {0}\nN: {1}\nDifference: {2}\n", sg_k, sg_k_new, diff);
sg_k = sg_k_new;
// mixing differences
diff = (pi_k - pi_k_new).Each(s => System.Math.Abs(s)).Sum();
Console.WriteLine("Mixing Coeffs:\nO: {0}\nN: {1}\nDifference: {2}\n", pi_k, pi_k_new, diff);
pi_k = pi_k_new;
Console.WriteLine("-------------------------------------------------------------");
} while (probability_difference > .0000000001 && mu_difference > .0000000001 && --max_iter >= 0);
}
