opencv/modules/legacy/src/em.cpp

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#include "precomp.hpp"

using namespace cv;

CvEMParams::CvEMParams() : nclusters(10), cov_mat_type(CvEM::COV_MAT_DIAGONAL),
    start_step(CvEM::START_AUTO_STEP), probs(0), weights(0), means(0), covs(0)
{
    term_crit=cvTermCriteria( CV_TERMCRIT_ITER+CV_TERMCRIT_EPS, 100, FLT_EPSILON );
}

CvEMParams::CvEMParams( int _nclusters, int _cov_mat_type, int _start_step,
                        CvTermCriteria _term_crit, const CvMat* _probs,
                        const CvMat* _weights, const CvMat* _means, const CvMat** _covs ) :
                        nclusters(_nclusters), cov_mat_type(_cov_mat_type), start_step(_start_step),
                        probs(_probs), weights(_weights), means(_means), covs(_covs), term_crit(_term_crit)
{}

CvEM::CvEM() : logLikelihood(DBL_MAX)
{
}

CvEM::CvEM( const CvMat* samples, const CvMat* sample_idx,
            CvEMParams params, CvMat* labels ) : logLikelihood(DBL_MAX)
{
    train(samples, sample_idx, params, labels);
}

CvEM::~CvEM()
{
    clear();
}

void CvEM::clear()
{
    emObj.clear();
}

void CvEM::read( CvFileStorage* fs, CvFileNode* node )
{
    FileNode fn(fs, node);
    emObj.read(fn);
    set_mat_hdrs();
}

void CvEM::write( CvFileStorage* _fs, const char* name ) const
{
    FileStorage fs = _fs;
    if(name)
        fs << name << "{";
    emObj.write(fs);
    if(name)
        fs << "}";
    fs.fs.obj = 0;
}

double CvEM::calcLikelihood( const Mat &input_sample ) const
{
    return emObj.predict(input_sample)[0];
}

float
CvEM::predict( const CvMat* _sample, CvMat* _probs ) const
{
    Mat prbs0 = cvarrToMat(_probs), prbs = prbs0, sample = cvarrToMat(_sample);
    int cls = static_cast<int>(emObj.predict(sample, _probs ? _OutputArray(prbs) : cv::noArray())[1]);
    if(_probs)
    {
        if( prbs.data != prbs0.data )
        {
            CV_Assert( prbs.size == prbs0.size );
            prbs.convertTo(prbs0, prbs0.type());
        }
    }
    return (float)cls;
}

void CvEM::set_mat_hdrs()
{
    if(emObj.isTrained())
    {
        meansHdr = emObj.get<Mat>("means");
        int K = emObj.get<int>("nclusters");
        covsHdrs.resize(K);
        covsPtrs.resize(K);
        const std::vector<Mat>& covs = emObj.get<vector<Mat> >("covs");
        for(size_t i = 0; i < covsHdrs.size(); i++)
        {
            covsHdrs[i] = covs[i];
            covsPtrs[i] = &covsHdrs[i];
        }
        weightsHdr = emObj.get<Mat>("weights");
        probsHdr = probs;
    }
}

static
void init_params(const CvEMParams& src,
                 Mat& prbs, Mat& weights,
                 Mat& means, vector<Mat>& covsHdrs)
{
    prbs = src.probs;
    weights = src.weights;
    means = src.means;

    if(src.covs)
    {
        covsHdrs.resize(src.nclusters);
        for(size_t i = 0; i < covsHdrs.size(); i++)
            covsHdrs[i] = src.covs[i];
    }
}

bool CvEM::train( const CvMat* _samples, const CvMat* _sample_idx,
                  CvEMParams _params, CvMat* _labels )
{
    CV_Assert(_sample_idx == 0);
    Mat samples = cvarrToMat(_samples), labels0, labels;
    if( _labels )
        labels0 = labels = cvarrToMat(_labels);
    
    bool isOk = train(samples, Mat(), _params, _labels ? &labels : 0);
    CV_Assert( labels0.data == labels.data );

    return isOk;
}

int CvEM::get_nclusters() const
{
    return emObj.get<int>("nclusters");
}

const CvMat* CvEM::get_means() const
{
    return emObj.isTrained() ? &meansHdr : 0;
}

const CvMat** CvEM::get_covs() const
{
    return emObj.isTrained() ? (const CvMat**)&covsPtrs[0] : 0;
}

const CvMat* CvEM::get_weights() const
{
    return emObj.isTrained() ? &weightsHdr : 0;
}

const CvMat* CvEM::get_probs() const
{
    return emObj.isTrained() ? &probsHdr : 0;
}

using namespace cv;

CvEM::CvEM( const Mat& samples, const Mat& sample_idx, CvEMParams params )
{
    train(samples, sample_idx, params, 0);
}

bool CvEM::train( const Mat& _samples, const Mat& _sample_idx,
                 CvEMParams _params, Mat* _labels )
{
    CV_Assert(_sample_idx.empty());
    Mat prbs, weights, means, logLikelihoods;
    std::vector<Mat> covsHdrs;
    init_params(_params, prbs, weights, means, covsHdrs);

    emObj = EM(_params.nclusters, _params.cov_mat_type, _params.term_crit);
    bool isOk = false;
    if( _params.start_step == EM::START_AUTO_STEP )
        isOk = emObj.train(_samples,
                           logLikelihoods, _labels ? _OutputArray(*_labels) : cv::noArray(), probs);
    else if( _params.start_step == EM::START_E_STEP )
        isOk = emObj.trainE(_samples, means, covsHdrs, weights,
                            logLikelihoods, _labels ? _OutputArray(*_labels) : cv::noArray(), probs);
    else if( _params.start_step == EM::START_M_STEP )
        isOk = emObj.trainM(_samples, prbs,
                            logLikelihoods, _labels ? _OutputArray(*_labels) : cv::noArray(), probs);
    else
        CV_Error(CV_StsBadArg, "Bad start type of EM algorithm");
    
    if(isOk)
    {
        logLikelihood = sum(logLikelihoods).val[0];
        set_mat_hdrs();
    }

    return isOk;
}

float
CvEM::predict( const Mat& _sample, Mat* _probs ) const
{
    return static_cast<float>(emObj.predict(_sample, _probs ? _OutputArray(*_probs) : cv::noArray())[1]);
}

int CvEM::getNClusters() const
{
    return emObj.get<int>("nclusters");
}

Mat CvEM::getMeans() const
{
    return emObj.get<Mat>("means");
}

void CvEM::getCovs(vector<Mat>& _covs) const
{
    _covs = emObj.get<vector<Mat> >("covs");
}

Mat CvEM::getWeights() const
{
    return emObj.get<Mat>("weights");
}

Mat CvEM::getProbs() const
{
    return probs;
}


/* End of file. */