Macros
// build into `.so` for interactive use
root [0] .L ArrayOfHists.C+
Info in <TUnixSystem::ACLiC>: creating shared library ./ArrayOfHists_C.so
root [1] arr_of_hists()
// quick and easy compile - use g++ or clang or whatever is appropriate
$ g++ -o ArrayOfHists.exe ArrayOfHists.C `root-config --cflags --libs`
$ ./ArrayOfHists.exe
Histograms
// Get better color palette.
gStyle->SetPalette(1);
// Command line rebin
h1->Rebin(); // by 2
h1->Rebin(5); // by 5
// Set background color to white
'Canvas 1'->SetFillColor(kWhite);
// print contents to file (bin, lower edge, err)
histo->Print("all"); > histo_out.txt
Chains
TChain ch("ch","ch")
ch->Add("SIM_minerva_00000513*.root/CCInclusiveReco",0)
TChain ch("ch","ch");
ch->Add("02/SIM_minerva_00000002_Subruns_*.root/RecoTracks",0)
ch->Add("04/SIM_minerva_00000004_Subruns_*.root/RecoTracks",0)
ch.MakeClass("RecoTracks")
Trees
TFile *_file0 = TFile::Open("/minerva/data/users/perdue/mc_production/nogrid/minerva/ana/v9r0p2/00/00/11/00/SIM_minerva_00001100_0001_Ana_Tuple_v1_v9r0p2.root")
TTree *mytree = _file0->Get("CCInclusiveReco")
mytree->Draw("ev_gate","n_prim_tracks_kinked>0")
TTree *mytree = _file0->Get("RecoTracks");
TTree *mytree = _file0->Get("MLVFSamplePrepTool");
TTree *mytree = _file0->Get("NukeCC")
NukeCC->GetEntries();
TTree *mytree = _file0->Get("NuECCQE")
mytree->MakeClass("NuECCQE")
Trees - Draw
mytree->Draw("myvar","","",1) # 1 event
mytree->Draw("myvar","","",1,10) # 1 event, use 10th event
mytree->Draw("myvar","","",10,10) # 10 events, start with 10th
Trees - Print
mytree->Scan("myvar[0]","","",1,1) # print element 0 of myvar array (1 event, start at 1)
Math
root [3] TMath::Factorial(3)
(Double_t)6.00000000000000000e+00
root [6] TMath::Factorial(3)*TMath::Factorial(3)/TMath::Factorial(6)
(double)5.00000000000000028e-02
root [7] 36/720
(const int)0
root [8] double(36/720)
(const double)0.00000000000000000e+00
root [9] 36./720.
(const double)5.00000000000000028e-02
root [10] double(36)/720
(const double)5.00000000000000028e-02
Classes
http://www-glast.slac.stanford.edu/software/root/howto/writing_root_classes.htm
GENIE Interactive Examples
$ genie gntp.100.ghep.root
genie[2] TTree *mytree = 0;
genie[3] _file0->GetObject("gtree", mytree);
genie[4] Long64_t nEntries = mytree->GetEntries();
genie[5] cout << nEntries << endl;
1000
genie[6] genie::NtpMCEventRecord* myentry = new genie::NtpMCEventRecord();
// ... (this will produce the welcome message)
genie[7] mytree->SetBranchAddress("gmcrec", &myentry);
genie[8] mytree->GetEntry(0);
genie[9] myentry->PrintToStream(cout);
// ... (a lot of stuff)
genie[10] myentry->event->XSec()
(const double)1.48164559715832651e-10
genie [1] TChain ch("gtree")
genie [2] ch->Add("/pnfs/minerva/scratch/users/minervapro/mc_production_genie_DFR_v10r8p4/grid/central_value/minerva/genie/v10r8p4/00/01/00/11/SIM_minerva_00010011_*_ghep.root/gtree",0)
genie [3] Long64_t nEntries = ch->GetEntries();
genie [4] cout << nEntries << endl;
100000
genie [5] genie::NtpMCEventRecord* myentry = new genie::NtpMCEventRecord();
// ...
genie [6] ch->SetBranchAddress("gmcrec", &myentry);
genie [7] ch->GetEntry(0);
genie [8] myentry->PrintToStream(cout);
// ...
genie [9] ch->GetEntry(2000);
genie [10] myentry->PrintToStream(cout);
// ...
genie [11] myentry->event->XSec()
(const double)3.35586289456737729e-12
genie [12] myentry->event.Summary()->ProcInfo()->IsMEC()
(const bool)1
genie [13] myentry->event.Summary()->ProcInfo()->ScatteringTypeId()
(const genie::ScatteringType_t)10
genie [14] myentry->event.Summary()->ProcInfo()->InteractionTypeAsString()
(class TString)"Weak[CC]"
genie [15] myentry->event.Summary()->ProcInfo()->ScatteringTypeAsString()