[mlpack-svn] r10286 - in mlpack/trunk/src/mlpack/methods/hmm: . distributions

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

Author: rcurtin
Date: 2011-11-15 17:05:53 -0500 (Tue, 15 Nov 2011)
New Revision: 10286

Added:
   mlpack/trunk/src/mlpack/methods/hmm/distributions/
   mlpack/trunk/src/mlpack/methods/hmm/distributions/discrete_distribution.cpp
   mlpack/trunk/src/mlpack/methods/hmm/distributions/discrete_distribution.hpp
Log:
Begin construction of Distribution classes so that we can generalize the HMM
class.


Added: mlpack/trunk/src/mlpack/methods/hmm/distributions/discrete_distribution.cpp
===================================================================
--- mlpack/trunk/src/mlpack/methods/hmm/distributions/discrete_distribution.cpp	                        (rev 0)
+++ mlpack/trunk/src/mlpack/methods/hmm/distributions/discrete_distribution.cpp	2011-11-15 22:05:53 UTC (rev 10286)
@@ -0,0 +1,30 @@
+/**
+ * @file discrete_distribution_impl.hpp
+ * @author Ryan Curtin
+ *
+ * Implementation of the discrete distribution.
+ */
+#ifndef __MLPACK_METHODS_HMM_DISTRIBUTIONS_DISCRETE_DISTRIBUTION_IMPL_HPP
+#define __MLPACK_METHODS_HMM_DISTRIBUTIONS_DISCRETE_DISTRIBUTION_IMPL_HPP
+
+// Just in case.
+#include "discrete_distribution.hpp"
+
+namespace mlpack {
+namespace distribution {
+
+// These functions are inlined because they are so simple.
+DiscreteDistribution::DiscreteDistribution(size_t numObservations)
+    : probability(numObservations)
+{ /* nothing to do */ }
+
+inline double DiscreteDistribution::Probability(size_t observation)
+{
+  // No bounds checking for speed reasons.
+  return probability(observation);
+}
+
+}; // namespace distribution
+}; // namespace mlpack
+
+#endif

Added: mlpack/trunk/src/mlpack/methods/hmm/distributions/discrete_distribution.hpp
===================================================================
--- mlpack/trunk/src/mlpack/methods/hmm/distributions/discrete_distribution.hpp	                        (rev 0)
+++ mlpack/trunk/src/mlpack/methods/hmm/distributions/discrete_distribution.hpp	2011-11-15 22:05:53 UTC (rev 10286)
@@ -0,0 +1,58 @@
+/**
+ * @file discrete_distribution.hpp
+ * @author Ryan Curtin
+ *
+ * Implementation of the discrete distribution, where each discrete observation
+ * has a given probability.
+ */
+#ifndef __MLPACK_METHODS_HMM_DISTRIBUTIONS_DISCRETE_DISTRIBUTION_HPP
+#define __MLPACK_METHODS_HMM_DISTRIBUTIONS_DISCRETE_DISTRIBUTION_HPP
+
+#include <mlpack/core.h>
+
+namespace mlpack {
+namespace distribution {
+
+/**
+ * A discrete distribution where the only observations are of type size_t.  This
+ * is useful (for example) with discrete Hidden Markov Models, where
+ * observations are non-negative integers representing specific emissions.
+ *
+ * No bounds checking is performed for observations, so if an invalid
+ * observation is passed (i.e. observation > numObservations), a crash will
+ * probably occur.
+ */
+class DiscreteDistribution
+{
+ public:
+  /**
+   * Define the discrete distribution as having numObservations possible
+   * observations.  The probability in each state will be set to (1 /
+   * numObservations).
+   *
+   * @param numObservations Number of possible observations this distribution
+   *    can have.
+   */
+  DiscreteDistribution(size_t numObservations);
+
+  /**
+   * Return the probability of the given observation.  If the observation is
+   * greater than the number of possible observations, then a crash will
+   * probably occur -- bounds checking is not performed.
+   *
+   * @param observation Observation to return the probability of.
+   * @return Probability of the given observation.
+   */
+  double Probability(size_t observation);
+
+ private:
+  arma::vec probability;
+};
+
+// Include inline implementation.
+#include "discrete_distribution_impl.hpp"
+
+}; // namespace distribution
+}; // namespace mlpack
+
+#endif