[mlpack-svn] r10574 - mlpack/trunk/src/mlpack/methods/gmm

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

Author: rcurtin
Date: 2011-12-06 03:38:53 -0500 (Tue, 06 Dec 2011)
New Revision: 10574

Modified:
   mlpack/trunk/src/mlpack/methods/gmm/gmm.cpp
Log:
It helps when you actually implement the stupid function instead of being an
idiot and thinking "well I'll just do it later but actually I'll forget that I
didn't do it and then not get to go to sleep instead".


Modified: mlpack/trunk/src/mlpack/methods/gmm/gmm.cpp
===================================================================
--- mlpack/trunk/src/mlpack/methods/gmm/gmm.cpp	2011-12-06 06:52:33 UTC (rev 10573)
+++ mlpack/trunk/src/mlpack/methods/gmm/gmm.cpp	2011-12-06 08:38:53 UTC (rev 10574)
@@ -32,7 +32,23 @@
  */
 arma::vec GMM::Random() const
 {
-  return "0 0";
+  // Determine which Gaussian it will be coming from.
+  double gaussRand = (double) rand() / (double) RAND_MAX;
+  size_t gaussian;
+
+  double sumProb = 0;
+  for (size_t g = 0; g < gaussians; g++)
+  {
+    sumProb += weights(g);
+    if (gaussRand <= sumProb)
+    {
+      gaussian = g;
+      break;
+    }
+  }
+
+  return trans(chol(covariances[gaussian])) *
+      arma::randn<arma::vec>(dimensionality) + means[gaussian];
 }
 
 void GMM::Estimate(const arma::mat& data)