root/ROOT/RNTupleDrawVisitor.hxx

0001 /// \file ROOT/RNTupleDrawVisitor.hxx
0002 /// \ingroup NTuple
0003 /// \author Sergey Linev <S.Linev@gsi.de>, Jakob Blomer <jblomer@cern.ch>
0004 /// \date 2025-07-24
0005
0006 /*************************************************************************
0007  * Copyright (C) 1995-2025, Rene Brun and Fons Rademakers.               *
0008  * All rights reserved.                                                  *
0009  *                                                                       *
0010  * For the licensing terms see $ROOTSYS/LICENSE.                         *
0011  * For the list of contributors see $ROOTSYS/README/CREDITS.             *
0012  *************************************************************************/
0013
0014 #ifndef ROOT_RNTupleDrawVisitor
0015 #define ROOT_RNTupleDrawVisitor
0016
0017 #include <ROOT/RField.hxx>
0018 #include <ROOT/RFieldVisitor.hxx>
0019 #include <ROOT/RNTupleReader.hxx>
0020 #include <ROOT/RNTupleView.hxx>
0021
0022 #include <TH1F.h>
0023
0024 #include <map>
0025 #include <memory>
0026 #include <string>
0027 #include <utility>
0028
0029 namespace ROOT {
0030
0031 namespace Internal {
0032
0033 class RNTupleDrawVisitor : public ROOT::Detail::RFieldVisitor {
0034 private:
0035    std::shared_ptr<ROOT::RNTupleReader> fNtplReader;
0036    std::unique_ptr<TH1> fHist;
0037    std::string fTitle;
0038
0039    /** Test collected entries if it looks like integer values and one can use better binning */
0040    void TestHistBuffer();
0041
0042    template <typename ViewT>
0043    void FillHistogramImpl(ViewT &view)
0044    {
0045       fHist = std::make_unique<TH1F>("hdraw", fTitle.c_str(), 100, 0, 0);
0046       fHist->SetDirectory(nullptr);
0047
0048       auto bufsize = (fHist->GetBufferSize() - 1) / 2;
0049       int cnt = 0;
0050       if (bufsize > 10) {
0051          bufsize -= 3;
0052       } else {
0053          bufsize = -1;
0054       }
0055
0056       for (auto i : view.GetFieldRange()) {
0057          fHist->Fill(view(i));
0058          if (++cnt == bufsize) {
0059             TestHistBuffer();
0060             ++cnt;
0061          }
0062       }
0063       if (cnt < bufsize)
0064          TestHistBuffer();
0065
0066       fHist->BufferEmpty();
0067    }
0068
0069    template <typename T>
0070    void FillHistogram(const ROOT::RIntegralField<T> &field)
0071    {
0072       auto view = fNtplReader->GetDirectAccessView<T>(field.GetOnDiskId());
0073       FillHistogramImpl(view);
0074    }
0075
0076    template <typename T>
0077    void FillHistogram(const ROOT::RField<T> &field)
0078    {
0079       auto view = fNtplReader->GetView<T>(field.GetOnDiskId());
0080       FillHistogramImpl(view);
0081    }
0082
0083    void FillStringHistogram(const ROOT::RField<std::string> &field)
0084    {
0085       std::map<std::string, std::uint64_t> values;
0086
0087       std::uint64_t nentries = 0;
0088
0089       auto view = fNtplReader->GetView<std::string>(field.GetOnDiskId());
0090       for (auto i : view.GetFieldRange()) {
0091          std::string v = view(i);
0092          nentries++;
0093          auto iter = values.find(v);
0094          if (iter != values.end())
0095             iter->second++;
0096          else if (values.size() >= 50)
0097             return;
0098          else
0099             values[v] = 0;
0100       }
0101
0102       // now create histogram with labels
0103       fHist = std::make_unique<TH1F>("h", fTitle.c_str(), 3, 0, 3);
0104       fHist->SetDirectory(nullptr);
0105       fHist->SetStats(0);
0106       fHist->SetEntries(nentries);
0107       fHist->SetCanExtend(TH1::kAllAxes);
0108       for (auto &entry : values)
0109          fHist->Fill(entry.first.c_str(), entry.second);
0110       fHist->LabelsDeflate();
0111       fHist->Sumw2(false);
0112    }
0113
0114 public:
0115    RNTupleDrawVisitor(std::shared_ptr<ROOT::RNTupleReader> ntplReader, const std::string &title)
0116       : fNtplReader(ntplReader), fTitle(title)
0117    {
0118    }
0119
0120    TH1 *MoveHist() { return fHist.release(); }
0121
0122    void VisitField(const ROOT::RFieldBase & /* field */) final {}
0123    void VisitBoolField(const ROOT::RField<bool> &field) final { FillHistogram(field); }
0124    void VisitFloatField(const ROOT::RField<float> &field) final { FillHistogram(field); }
0125    void VisitDoubleField(const ROOT::RField<double> &field) final { FillHistogram(field); }
0126    void VisitCharField(const ROOT::RField<char> &field) final { FillHistogram(field); }
0127    void VisitInt8Field(const ROOT::RIntegralField<std::int8_t> &field) final { FillHistogram(field); }
0128    void VisitInt16Field(const ROOT::RIntegralField<std::int16_t> &field) final { FillHistogram(field); }
0129    void VisitInt32Field(const ROOT::RIntegralField<std::int32_t> &field) final { FillHistogram(field); }
0130    void VisitInt64Field(const ROOT::RIntegralField<std::int64_t> &field) final { FillHistogram(field); }
0131    void VisitStringField(const ROOT::RField<std::string> &field) final { FillStringHistogram(field); }
0132    void VisitUInt16Field(const ROOT::RIntegralField<std::uint16_t> &field) final { FillHistogram(field); }
0133    void VisitUInt32Field(const ROOT::RIntegralField<std::uint32_t> &field) final { FillHistogram(field); }
0134    void VisitUInt64Field(const ROOT::RIntegralField<std::uint64_t> &field) final { FillHistogram(field); }
0135    void VisitUInt8Field(const ROOT::RIntegralField<std::uint8_t> &field) final { FillHistogram(field); }
0136    void VisitCardinalityField(const ROOT::RCardinalityField &field) final
0137    {
0138       if (const auto f32 = field.As32Bit()) {
0139          FillHistogram(*f32);
0140       } else if (const auto f64 = field.As64Bit()) {
0141          FillHistogram(*f64);
0142       }
0143    }
0144 }; // class RDrawVisitor
0145
0146 } // namespace Internal
0147 } // namespace ROOT
0148
0149 #endif