RecoTauMVAHelper.h

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#ifndef RecoTauTag_RecoTau_RecoTauMVAHelper_h
#define RecoTauTag_RecoTau_RecoTauMVAHelper_h

/*
 * RecoTauMVAHelper
 *
 * Manages DB retrieval and application of MVAComputers to reco::PFTaus.  Takes
 * as input a name (into an MVAComputerContainer) and an optional esLabel.  The
 * MVA helper retrieves the MVA from the database and determines the associated
 * list of discriminant functions.  These discriminant functions are all defined
 * as RecoTauDiscriminantPlugins.  This class then builds the appropriate
 * plugins.  When passed a tau using operator(), the class computes the output
 * of all discriminates, passes them to the MVA, and returns the result.
 *
 * The plugin can also be used to pass training data to the MVA framework.  See
 * RecoTauTag/TauTagTools/test/training for examples.
 *
 * Options for the different plugins can be specified with the pluginOptions.
 * Any entry in the pluginOptionPSet will passed to the plugin of the same name.
 *
 * Author: Evan K. Friis (UC Davis)
 *
 * Based on code by Christophe Saoute in -
 * PhysicsTools/MVAComputer/interface/MVAModuleHelper.h
 */

#include <boost/ptr_container/ptr_map.hpp>
#include <string>

#include "RecoTauTag/RecoTau/interface/RecoTauDiscriminantPlugins.h"

#include "PhysicsTools/MVAComputer/interface/MVAComputerCache.h"
#include "PhysicsTools/MVAComputer/interface/Variable.h"
#include "DataFormats/TauReco/interface/PFTauFwd.h"
#include "FWCore/Framework/interface/EventSetup.h"
#include "FWCore/Framework/interface/Event.h"

namespace reco { namespace tau {

class RecoTauMVAHelper {
  public:
    explicit RecoTauMVAHelper(const std::string &name,
                              const std::string &eslabel,
                              const edm::ParameterSet &pluginOptions);
    ~RecoTauMVAHelper() {}

    // Setup event information and retrive MVA from DB
    void setEvent(const edm::Event& evt, const edm::EventSetup &es);

    // Apply MVA to tau and return result
    double operator()(const PFTauRef &tau) const;

    // Retrive the raw input for a given tau that would be passed to the MVA
    const PhysicsTools::Variable::ValueList& discriminants(
        const PFTauRef& tau) const;

    // Add a training event of type <target> with given weight
    void train(const PFTauRef &tau, bool target, double weight = 1.0) const;
  private:
    // Name of computer in the DB record
    std::string name_;
    // Name of label for event setup record
    std::string eslabel_;
    // Options to pass to the plugins
    edm::ParameterSet pluginOptions_;

    PhysicsTools::MVAComputerCache computer_;
    // Map our discriminant plugins to their "MVA name"
    typedef boost::ptr_map<PhysicsTools::AtomicId, RecoTauDiscriminantPlugin>
        PluginMap;
    PluginMap plugins_;
    // Helper function to load relevant plugins for a MVA computer
    void loadDiscriminantPlugins(
        const PhysicsTools::Calibration::MVAComputer &computer);
    // Load the plugin values for this tau
    void fillValues(const reco::PFTauRef& tau) const;
    mutable PhysicsTools::Variable::ValueList values_;
};
}}  // end reco::tau
#endif