Copy a subset of a Tree to a new Tree
The input file has been generated by the program in $ROOTSYS/test/Event
with Event 1000 1 1 1.
Author: Rene Brun
This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Thursday, August 18, 2022 at 09:51 AM.
.! $ROOTSYS/test/eventexe 1000 1 1 1
event:0, rtime=0.581203 s event:100, rtime=0.241684 s event:200, rtime=0.236820 s event:300, rtime=0.234422 s event:400, rtime=0.235594 s event:500, rtime=0.233579 s event:600, rtime=0.246538 s event:700, rtime=0.235027 s event:800, rtime=0.260622 s event:900, rtime=0.070335 s ****************************************************************************** *Tree :T : An example of a ROOT tree * *Entries : 1000 : Total = 81215880 bytes File Size = 37645437 * * : : Tree compression factor = 2.16 * ****************************************************************************** *Branch :event * *Entries : 1000 : BranchElement (see below) * *............................................................................* *Br 0 :TObject : BASE * *Entries : 1000 : Total Size= 14667 bytes File Size = 1807 * *Baskets : 2 : Basket Size= 51200 bytes Compression= 7.84 * *............................................................................* *Br 1 :fType[20] : Char_t * *Entries : 1000 : Total Size= 24760 bytes File Size = 2239 * *Baskets : 3 : Basket Size= 51200 bytes Compression= 10.83 * *............................................................................* *Br 2 :fEventName : char* * *Entries : 1000 : Total Size= 23661 bytes File Size = 4837 * *Baskets : 3 : Basket Size= 51200 bytes Compression= 4.78 * *............................................................................* *Br 3 :fNtrack : Int_t * *Entries : 1000 : Total Size= 4651 bytes File Size = 1303 * *Baskets : 2 : Basket Size= 51200 bytes Compression= 3.18 * *............................................................................* *Br 4 :fNseg : Int_t * *Entries : 1000 : Total Size= 4639 bytes File Size = 1897 * *Baskets : 2 : Basket Size= 51200 bytes Compression= 2.18 * *............................................................................* *Br 5 :fNvertex : Int_t * *Entries : 1000 : Total Size= 4657 bytes File Size = 1264 * *Baskets : 2 : Basket Size= 51200 bytes Compression= 3.28 * *............................................................................* *Br 6 :fFlag : UInt_t * *Entries : 1000 : Total Size= 4639 bytes File Size = 638 * *Baskets : 2 : Basket Size= 51200 bytes Compression= 6.49 * *............................................................................* *Br 7 :fTemperature : Double32_t * *Entries : 1000 : Total Size= 4681 bytes File Size = 3409 * *Baskets : 2 : Basket Size= 51200 bytes Compression= 1.22 * *............................................................................* *Br 8 :fMeasures[10] : Int_t * *Entries : 1000 : Total Size= 44877 bytes File Size = 14728 * *Baskets : 4 : Basket Size= 51200 bytes Compression= 3.01 * *............................................................................* *Br 9 :fMatrix[4][4] : Double32_t * *Entries : 1000 : Total Size= 68964 bytes File Size = 42323 * *Baskets : 5 : Basket Size= 51200 bytes Compression= 1.62 * *............................................................................* *Br 10 :fClosestDistance : Double32_t fClosestDistance[fNvertex] * *Entries : 1000 : Total Size= 37612 bytes File Size = 21554 * *Baskets : 4 : Basket Size= 51200 bytes Compression= 1.71 * *............................................................................* *Br 11 :fEvtHdr : EventHeader * *Entries : 1000 : Total Size= 22750 bytes File Size = 4439 * *Baskets : 3 : Basket Size= 51200 bytes Compression= 5.01 * *............................................................................* *Br 12 :fTracks : TClonesArray* * *Entries : 1000 : Total Size= 75907240 bytes File Size = 36784634 * *Baskets : 801 : Basket Size= 25600000 bytes Compression= 2.06 * *............................................................................* *Br 13 :fHighPt : TRefArray* * *Entries : 1000 : Total Size= 1514544 bytes File Size = 589634 * *Baskets : 81 : Basket Size= 632832 bytes Compression= 2.56 * *............................................................................* *Br 14 :fMuons : TRefArray* * *Entries : 1000 : Total Size= 71535 bytes File Size = 9289 * *Baskets : 5 : Basket Size= 51200 bytes Compression= 7.65 * *............................................................................* *Br 15 :fLastTrack : TRef * *Entries : 1000 : Total Size= 16771 bytes File Size = 3588 * *Baskets : 3 : Basket Size= 51200 bytes Compression= 4.53 * *............................................................................* *Br 16 :fWebHistogram : TRef * *Entries : 1000 : Total Size= 16792 bytes File Size = 1847 * *Baskets : 3 : Basket Size= 51200 bytes Compression= 8.80 * *............................................................................* *Br 17 :fH : TH1F* * *Entries : 1000 : Total Size= 961299 bytes File Size = 96581 * *Baskets : 51 : Basket Size= 404480 bytes Compression= 9.94 * *............................................................................* *Br 18 :fTriggerBits : TBits * *Entries : 1000 : Total Size= 41317 bytes File Size = 13039 * *Baskets : 4 : Basket Size= 51200 bytes Compression= 3.13 * *............................................................................* *Br 19 :fIsValid : Bool_t * *Entries : 1000 : Total Size= 1657 bytes File Size = 193 * *Baskets : 2 : Basket Size= 51200 bytes Compression= 5.93 * *............................................................................* *Br 20 :TRefTable : List of branch numbers with referenced objects * *Entries : 1000 : Total Size= 2422133 bytes File Size = 33640 * *Baskets : 76 : Basket Size= 32000 bytes Compression= 71.07 * *............................................................................* 1000 events and 78625869 bytes processed. RealTime=3.260800 seconds, CpuTime=3.090000 seconds compression level=1, split=1, arg4=1, IMT=0, compression algorithm=1 You write 24.112447 Mbytes/Realtime seconds You write 25.445265 Mbytes/Cputime seconds
Arguments are defined.
TString dir = "$ROOTSYS/test/Event.root";
gSystem->ExpandPathName(dir);
const auto filename = gSystem->AccessPathName(dir) ? "./Event.root" : "$ROOTSYS/test/Event.root";
TFile oldfile(filename);
TTree *oldtree;
oldfile.GetObject("T", oldtree);
Warning in <TClass::Init>: no dictionary for class Event is available Warning in <TClass::Init>: no dictionary for class EventHeader is available Warning in <TClass::Init>: no dictionary for class Track is available
Deactivate all branches
oldtree->SetBranchStatus("*", 0);
Activate only four of them
for (auto activeBranchName : {"event", "fNtrack", "fNseg", "fH"})
oldtree->SetBranchStatus(activeBranchName, 1);
Create a new file + a clone of old tree in new file
TFile newfile("small.root", "recreate");
auto newtree = oldtree->CloneTree();
newtree->Print();
newfile.Write();
****************************************************************************** *Tree :T : An example of a ROOT tree * *Entries : 1000 : Total = 975986 bytes File Size = 66888 * * : : Tree compression factor = 11.53 * ****************************************************************************** *Branch :event * *Entries : 1000 : BranchElement (see below) * *............................................................................* *Br 0 :fNtrack : Int_t * *Entries : 1000 : Total Size= 4730 bytes File Size = 972 * *Baskets : 1 : Basket Size= 3072 bytes Compression= 3.37 * *............................................................................* *Br 1 :fNseg : Int_t * *Entries : 1000 : Total Size= 4716 bytes File Size = 1435 * *Baskets : 1 : Basket Size= 3072 bytes Compression= 2.28 * *............................................................................* *Br 2 :fH : TH1F* * *Entries : 1000 : Total Size= 956785 bytes File Size = 64481 * *Baskets : 2 : Basket Size= 773120 bytes Compression= 11.86 * *............................................................................* *Br 3 :TRefTable : List of branch numbers with referenced objects * *Entries : 1000 : Total Size= 8613 bytes One basket in memory * *Baskets : 0 : Basket Size= 32000 bytes Compression= 1.00 * *............................................................................*