PixelResolutionHistograms.h

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#ifndef FastSimulation_TrackingRecHitProducer_PixelResolutionHistograms_h
#define FastSimulation_TrackingRecHitProducer_PixelResolutionHistograms_h 1

class TFile;
class TH1F;
class TH2F;
class TAxis;
class RandomEngineAndDistribution;
class SimpleHistogramGenerator;

#include <memory>


static constexpr unsigned int COTBETA_HIST_MAX = 30;
static constexpr unsigned int COTALPHA_HIST_MAX = 20;
static constexpr unsigned int QBIN_HIST_MAX = 4;

class PixelResolutionHistograms {
public:
  //--- Constructor to use when generating resolution histograms.
  //    We make empty histograms (which we own), but generator pointers
  //    remain null.
  //
  PixelResolutionHistograms(std::string filename,     // ROOT file for histograms
                            std::string rootdir,      // Subdirectory in the file, "" if none
                            std::string descTitle,    // Descriptive title
                            unsigned int detType,     // Where we are... (&&& do we need this?)
                            double cotbetaBinWidth,   // cot(beta) : bin width,
                            double cotbetaLowEdge,    //           : low endpoint,
                            int cotbetaBins,          //           : # of bins
                            double cotalphaBinWidth,  // cot(alpha): bin width,
                            double cotalphaLowEdge,   //           : low endpoint,
                            int cotalphaBins);        //           : # of bins
                                                      //int qbinWidth,
                                                      //int qbins )

  //--- Constructor to use when reading the histograms from a file (e.g. when
  //    inside a running FastSim job).  We get the histograms from a
  //    ROOT file, and we do *not* own them.  But we do own the
  //    generators.
  //
  PixelResolutionHistograms(std::string filename,        // ROOT file for histograms
                            std::string rootdir = "",    // ROOT dir, "" if none
                            int detType = -1,            // default: read from ROOT file.
                            bool ignore_multi = false,   // Forward Big is always single
                            bool ignore_single = false,  // Edge does not need single pixels
                            bool ignore_qBin = false);   // qBin histograms not used right now (future expansion)

  //--- Destructor (virtual, just in case)
  virtual ~PixelResolutionHistograms();

  //--- Status after construction (esp.loading from file). Non-zero if there
  //    were problems.
  inline int status() { return status_; }

  //--- Fill one entry in one resolution histogram.  Use when making histograms.
  int Fill(double dx,
           double dy,  // the difference wrt true hit
           double cotalpha,
           double cotbeta,  // cotangent of local angles
           int qbin,        // Qbin = category for how much charge we have
           int nxpix,
           int nypix);  // length of cluster along x,y (only care if ==1 or not)

  //--- Get generators, for resolution in X and Y.  Use in FastSim.
  const SimpleHistogramGenerator* getGeneratorX(double cotalpha, double cotbeta, int qbin, bool singlex);

  const SimpleHistogramGenerator* getGeneratorY(double cotalpha, double cotbeta, int qbin, bool singley);

private:
  // Do we own the histograms, or not?
  bool weOwnHistograms_;

  // Where we are.
  unsigned int detType_;  // 1 for barrel, 0 for forward  /// May not need this?

  // Resolution binning
  double cotbetaBinWidth_;
  double cotbetaLowEdge_;
  int cotbetaBins_;
  double cotalphaBinWidth_;
  double cotalphaLowEdge_;
  int cotalphaBins_;
  int qbinWidth_;
  int qbins_;

  // The dummy histogram to hold the binning, and the two cached axes.
  TH2F* binningHisto_;
  TAxis* cotbetaAxis_;
  TAxis* cotalphaAxis_;

  // Resolution histograms.  I (Petar) tried to dynamically allocate
  // these histograms, but all possible implementations were somewhat
  // complicated, which would make the code harder to understand,
  // debug, and thus support in the long term.  Since we are here only
  // booking pointers of histograms, we will instead book larger
  // matrices, and leave them partially empty.  But who cares -- the
  // wasted memory of a few hundred null pointers is negligible.
  //
  // The constructor will then fill only the first cotbetaBins_ x
  // cotalphaBins_ x qbinBins_ histograms in the matrix, and we'll
  // ignore the rest.
  //
  TH1F* resMultiPixelXHist_[COTBETA_HIST_MAX][COTALPHA_HIST_MAX][QBIN_HIST_MAX];
  TH1F* resSinglePixelXHist_[COTBETA_HIST_MAX][COTALPHA_HIST_MAX];
  TH1F* resMultiPixelYHist_[COTBETA_HIST_MAX][COTALPHA_HIST_MAX][QBIN_HIST_MAX];
  TH1F* resSinglePixelYHist_[COTBETA_HIST_MAX][COTALPHA_HIST_MAX];
  TH1F* qbinHist_[COTBETA_HIST_MAX][COTALPHA_HIST_MAX];

  // File with histograms to load.
  std::unique_ptr<TFile> file_;

  // Status of loading.  Check if there were errors.
  int status_;

  // Identical binning and parameterization for FastSim generators.
  SimpleHistogramGenerator* resMultiPixelXGen_[COTBETA_HIST_MAX][COTALPHA_HIST_MAX][QBIN_HIST_MAX];
  SimpleHistogramGenerator* resSinglePixelXGen_[COTBETA_HIST_MAX][COTALPHA_HIST_MAX];
  SimpleHistogramGenerator* resMultiPixelYGen_[COTBETA_HIST_MAX][COTALPHA_HIST_MAX][QBIN_HIST_MAX];
  SimpleHistogramGenerator* resSinglePixelYGen_[COTBETA_HIST_MAX][COTALPHA_HIST_MAX];
  SimpleHistogramGenerator* qbinGen_[COTBETA_HIST_MAX][COTALPHA_HIST_MAX];
};
#endif