Cluster1DCleaner.h

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#ifndef _Cluster1DCleaner_H_
#define _Cluster1DCleaner_H_

#include "CommonTools/Clustering1D/interface/Cluster1D.h"

/*
 * given a vector<Cluster1D<T> >, erase Cluster1D further away than 
 * ZOffeSet from the average position, then 
 * recompute the vertex position. The ZOffeSet is taken as 
 * an aurgument
*/
template < class T >
class Cluster1DCleaner
{
public:

    Cluster1DCleaner(const float zoffset, bool useErr):
        theZOffSet(zoffset), theUseError(useErr)
    {
        theCleanedCluster1Ds.clear();
        theDiscardedCluster1Ds.clear();
    }
    // return the compatible clusters
    std::vector< Cluster1D< T > > clusters( const std::vector< Cluster1D< T > >& );
    /*
       return the vector of discarded Cluster1Ds
       it should be called after Cluster1DCleaner::clusters
       otherwise return an empty vector
    */
    std::vector< Cluster1D< T > > discardedCluster1Ds() const
    {
        return theDiscardedCluster1Ds;
    }
    
private:
    void cleanCluster1Ds(const std::vector<Cluster1D<T> >& );
    float average(const std::vector<Cluster1D<T> >&);
    std::vector<Cluster1D<T> > theCleanedCluster1Ds;
    std::vector<Cluster1D<T> > theDiscardedCluster1Ds;
    float theZOffSet;
    bool theUseError;
};

/*
 *                                implementation
 */

template <class T>
std::vector<Cluster1D<T> >
Cluster1DCleaner<T>::clusters(const std::vector<Cluster1D<T> >& _clust)
{
    std::vector<Cluster1D<T> > clust = _clust;
    cleanCluster1Ds(clust);
    return theCleanedCluster1Ds;
}

template <class T>
void
Cluster1DCleaner<T>::cleanCluster1Ds(const std::vector<Cluster1D<T> >& _clust)
{
    std::vector<Cluster1D<T> > clust = _clust;
    theCleanedCluster1Ds.clear();
    theDiscardedCluster1Ds.clear();
    if (clust.size() == 0)
        return;
    float oldPos = average(clust);
    for( typename std::vector < Cluster1D<T> >::const_iterator ic=clust.begin();
            ic != clust.end(); ic++)
    {
        float discr =
            theUseError ? fabs( ((*ic).position().value() - oldPos) / (*ic).position().error())
            : fabs( ((*ic).position().value() - oldPos) );
        if ( discr < theZOffSet )
        {
            theCleanedCluster1Ds.push_back(*ic);
        }
        else
        {
            theDiscardedCluster1Ds.push_back(*ic);
        }
    }
    return;
}

//I could use the Cluster1DMerger...
template <class T>
float
Cluster1DCleaner<T>::average(const std::vector<Cluster1D<T> >& clust)
{
    float ave = clust.front().position().value();
    float err = clust.front().position().error();
    for( typename std::vector < Cluster1D<T> >::const_iterator ic=(clust.begin())+1;
         ic != clust.end(); ic++)
    {
        float oldave = ave;
        float olderr = err;
        ave = ( oldave/olderr/olderr +
                ic->position().value()/ic->position().error()/ic->position().error()) /
              (1./olderr/olderr + 1./ic->position().error()/ic->position().error());
        err = sqrt(olderr*olderr + ic->position().error()*ic->position().error());
    }
    return ave;
}

#endif