Saving / snapshotting a new branch with RDataFrame

ROOT
1

Hi, I have an RDataFrame and want to use it to skim a file, add branches, and save the output:

df.Define("goodjet_pt",    "Jet_pt[0]")
branches = ["nElectron", "nPhoton", "nMuon", "Photon_pt", "Muon_pt", "MET_pt", "goodjet_pt"]
df.Snapshot("Events", ofile, branches)

All branches but goodjet_pt are already there in the input file, so it just copies them over. But I cannot seem to define a new branch and save it in the output file. It crashes with:

    df.Snapshot("Events", ofile, branches)
TypeError: Template method resolution failed:
  none of the 3 overloaded methods succeeded. Full details:
  ROOT::RDF::RResultPtr<ROOT::RDF::RInterface<ROOT::Detail::RDF::RLoopManager,void> > ROOT::RDF::RInterface<ROOT::Detail::RDF::RJittedFilter,void>::Snapshot(basic_string_view<char,char_traits<char> > treename, basic_string_view<char,char_traits<char> > filename, initializer_list<string> columnList, const ROOT::RDF::RSnapshotOptions& options = ROOT::RDF::RSnapshotOptions()) =>
    TypeError: could not convert argument 3
  ROOT::RDF::RResultPtr<ROOT::RDF::RInterface<ROOT::Detail::RDF::RLoopManager,void> > ROOT::RDF::RInterface<ROOT::Detail::RDF::RJittedFilter,void>::Snapshot(basic_string_view<char,char_traits<char> > treename, basic_string_view<char,char_traits<char> > filename, const vector<string>& columnList, const ROOT::RDF::RSnapshotOptions& options = ROOT::RDF::RSnapshotOptions()) =>
    runtime_error: Unknown column: goodjet_pt
  ROOT::RDF::RResultPtr<ROOT::RDF::RInterface<ROOT::Detail::RDF::RLoopManager,void> > ROOT::RDF::RInterface<ROOT::Detail::RDF::RJittedFilter,void>::Snapshot(basic_string_view<char,char_traits<char> > treename, basic_string_view<char,char_traits<char> > filename, basic_string_view<char,char_traits<char> > columnNameRegexp = "", const ROOT::RDF::RSnapshotOptions& options = ROOT::RDF::RSnapshotOptions()) =>
    TypeError: could not convert argument 3
  ROOT::RDF::RResultPtr<ROOT::RDF::RInterface<ROOT::Detail::RDF::RLoopManager,void> > ROOT::RDF::RInterface<ROOT::Detail::RDF::RJittedFilter,void>::Snapshot(basic_string_view<char,char_traits<char> > treename, basic_string_view<char,char_traits<char> > filename, initializer_list<string> columnList, const ROOT::RDF::RSnapshotOptions& options = ROOT::RDF::RSnapshotOptions()) =>
    TypeError: could not convert argument 3

Do you know what’s going on?

Thanks!

2

df = df.Define(“goodjet_pt”, “Jet_pt[0]”)

works!

Problem solved. :slight_smile:

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