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fixed likelihood computing

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This commit is contained in:
Maria Dimashova 2012-04-10 14:03:05 +00:00
parent 411467eab8
commit 6cbd36fd1e
1 changed files with 9 additions and 8 deletions
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17
modules/ml/src/em.cpp
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@ -511,26 +511,27 @@ void EM::computeProbabilities(const Mat& sample, int& label, Mat* probs, double*
if(!probs && !logLikelihood) if(!probs && !logLikelihood)
return; return;
Mat buf, *sampleProbs = probs ? probs : &buf;
Mat expL_Lmax(L.size(), CV_64FC1); Mat expL_Lmax(L.size(), CV_64FC1);
double maxLVal = L.at<double>(label); double maxLVal = L.at<double>(label);
for(int i = 0; i < L.cols; i++) for(int i = 0; i < L.cols; i++)
expL_Lmax.at<double>(i) = std::exp(L.at<double>(i) - maxLVal); expL_Lmax.at<double>(i) = std::exp(L.at<double>(i) - maxLVal);
double partSum = 0, // sum_j!=q (exp(L_ij - L_iq)) double partSum = 0; // sum_j!=q (exp(L_ij - L_iq))
factor; // 1/(1 + partExpSum)
for(int clusterIndex = 0; clusterIndex < nclusters; clusterIndex++) for(int clusterIndex = 0; clusterIndex < nclusters; clusterIndex++)
if(clusterIndex != label) if(clusterIndex != label)
partSum += expL_Lmax.at<double>(clusterIndex); partSum += expL_Lmax.at<double>(clusterIndex);
factor = 1./(1 + partSum);
sampleProbs->create(1, nclusters, CV_64FC1); if(probs)
expL_Lmax *= factor; {
expL_Lmax.copyTo(*sampleProbs); probs->create(1, nclusters, CV_64FC1);
double factor = 1./(1 + partSum);
expL_Lmax *= factor;
expL_Lmax.copyTo(*probs);
}
if(logLikelihood) if(logLikelihood)
{ {
double logWeightProbs = std::log(weights.dot(*sampleProbs)); double logWeightProbs = std::log((1 + partSum) * std::exp(maxLVal)) - 0.5 * dim * CV_LOG2PI;
*logLikelihood = logWeightProbs; *logLikelihood = logWeightProbs;
} }
} }