public void ConstructorTest4()
{
#region doc_fit_epanechnikov
// Suppose we have the following data, and we would
// like to estimate a distribution from this data
double[][] samples =
{
new double[] { 0, 1 },
new double[] { 1, 2 },
new double[] { 5, 1 },
new double[] { 7, 1 },
new double[] { 6, 1 },
new double[] { 5, 7 },
new double[] { 2, 1 },
};
// Start by specifying a density kernel
IDensityKernel kernel = new EpanechnikovKernel(dimension: 2);
// Create a multivariate Empirical distribution from the samples
var dist = new MultivariateEmpiricalDistribution(kernel, samples);
// Common measures
double[] mean = dist.Mean; // { 3.71, 2.00 }
double[] median = dist.Median; // { 3.71, 2.00 }
double[] var = dist.Variance; // { 7.23, 5.00 } (diagonal from cov)
double[,] cov = dist.Covariance; // { { 7.23, 0.83 }, { 0.83, 5.00 } }
// Probability mass functions
double pdf1 = dist.ProbabilityDensityFunction(new double[] { 2, 1 }); // 0.039131176997318849
double pdf2 = dist.ProbabilityDensityFunction(new double[] { 4, 2 }); // 0.010212109770266639
double pdf3 = dist.ProbabilityDensityFunction(new double[] { 5, 7 }); // 0.02891906722705221
double lpdf = dist.LogProbabilityDensityFunction(new double[] { 5, 7 }); // -3.5432541357714742
#endregion
Assert.AreEqual(3.7142857142857144, mean[0]);
Assert.AreEqual(2.0, mean[1]);
Assert.AreEqual(3.7142857142857144, median[0]);
Assert.AreEqual(2.0, median[1]);
Assert.AreEqual(7.2380952380952381, var[0]);
Assert.AreEqual(5.0, var[1]);
Assert.AreEqual(7.2380952380952381, cov[0, 0]);
Assert.AreEqual(0.83333333333333337, cov[0, 1]);
Assert.AreEqual(0.83333333333333337, cov[1, 0]);
Assert.AreEqual(5.0, cov[1, 1]);
Assert.AreEqual(0.039131176997318849, pdf1);
Assert.AreEqual(0.010212109770266639, pdf2);
Assert.AreEqual(0.02891906722705221, pdf3);
Assert.AreEqual(-3.5432541357714742, lpdf);
}
public void EpanechnikovKernelTest()
{
EpanechnikovKernel kernel = new EpanechnikovKernel(dimension: 1);
Assert.AreEqual(3.0 / 4.0, kernel.Constant);
double[] actual = new double[11];
for (int i = 0; i < actual.Length; i++)
{
actual[i] = kernel.Function((i - 5) / 10.0);
}
double[] expected =
{
0.5625, 0.63, 0.6825, 0.72, 0.74249999999999994,
0.75,
0.74249999999999994, 0.72, 0.6825, 0.63, 0.5625
};
for (int i = 0; i < actual.Length; i++)
{
Assert.AreEqual(expected[i], actual[i]);
}
}
