[mlpack-svn] r17278 - mlpack/trunk/src/mlpack/core/dists

[fastlab-svn at coffeetalk-1.cc.gatech.edu]

Author: michaelfox99
Date: Sun Nov  2 12:52:53 2014
New Revision: 17278

Log:
Rename hmm_regression.hpp


Added:
   mlpack/trunk/src/mlpack/core/dists/regression_distribution.hpp

Added: mlpack/trunk/src/mlpack/core/dists/regression_distribution.hpp
==============================================================================
--- (empty file)
+++ mlpack/trunk/src/mlpack/core/dists/regression_distribution.hpp	Sun Nov  2 12:52:53 2014
@@ -0,0 +1,102 @@
+/**
+ * @file regression_distribution.hpp
+ * @author Michael Fox
+ *
+ * Implementation of conditional Gaussian distribution for HMM regression (HMMR)
+ */
+#ifndef __MLPACK_METHODS_HMM_DISTRIBUTIONS_REGRESSION_DISTRIBUTION_HPP
+#define __MLPACK_METHODS_HMM_DISTRIBUTIONS_REGRESSION_DISTRIBUTION_HPP
+
+#include <mlpack/core.hpp>
+#include <mlpack/core/dists/gaussian_distribution.hpp>
+#include <mlpack/methods/linear_regression/linear_regression.hpp>
+
+namespace mlpack {
+namespace distribution {
+
+/**
+ * A class that represents a univariate conditionally Gaussian distribution.
+ * Can be used as an emission distribution with the hmm class to implement HMM
+ * regression (HMMR) as described in
+ * https://www.ima.umn.edu/preprints/January1994/1195.pdf
+ * The hmm observations should have the dependent variable in the first row,
+ * with the independent variables in the other rows. 
+ */
+class RegressionDistribution
+{
+ private:
+  //! Regression function for representing conditional mean.   
+  regression::LinearRegression rf;   
+  //! Error distribution
+  GaussianDistribution err;
+  
+ public:
+  /**
+   * Default constructor, which creates a Gaussian with zero dimension.
+   */
+  RegressionDistribution() { /* nothing to do */ }
+
+  /**
+   * Create a Conditional Gaussian distribution with conditional mean function
+   * obtained by running RegressionFunction on predictors, responses. 
+   * 
+   * @param predictors Matrix of predictors (X).
+   * @param responses Vector of responses (y).
+   */
+  RegressionDistribution(const arma::mat& predictors,
+                                  const arma::vec& responses) :
+      rf(regression::LinearRegression(predictors, responses))    
+  {
+      err = GaussianDistribution(1);
+      err.Covariance() = rf.ComputeError(predictors, responses);
+  }
+
+  /**
+   * Returns a string representation of this object.
+   */
+  std::string ToString() const;
+ 
+  // Return regression function
+  const regression::LinearRegression& Rf() {return rf;}
+
+  /**
+   * Estimate the Gaussian distribution directly from the given observations.
+   *
+   * @param observations List of observations.
+   */
+  void Estimate(const arma::mat& observations);
+  
+  /**
+   * Estimate parameters using provided observation weights
+   *
+   * @param weights probability that given observation is from distribution
+   */
+  void Estimate(const arma::mat& observations, const arma::vec& weights);
+  
+  /**
+  * Evaluate probability density function of given observation  
+  *
+  * @param observation point to evaluate probability at
+  */
+  double Probability(const arma::vec& observation) const;
+  
+  /**
+   * Calculate y_i for each data point in points.
+   *
+   * @param points the data points to calculate with.
+   * @param predictions y, will contain calculated values on completion.
+   */
+  void Predict(const arma::mat& points, arma::vec& predictions) const;
+  
+   //! Return the parameters (the b vector).
+  const arma::vec& Parameters() const { return rf.Parameters(); }
+
+  //! Return the dimensionality (2) NEED TO FIX THIS
+  static const size_t Dimensionality() { return 2; }
+};
+
+
+}; // namespace distribution
+}; // namespace mlpack
+
+#endif