Example of a circular Tree
Circular Trees are interesting in online real time environments to store the results of the last maxEntries events. for more info, see TTree::SetCircular. Circular trees must be memory resident.
Author: Rene Brun
This notebook tutorial was automatically generated with ROOTBOOK-izer from the macro found in the ROOT repository on Wednesday, April 17, 2024 at 11:23 AM.
auto T = new TTree("T","test circular buffers");
TRandom r;
Float_t px,py,pz;
Double_t randomNum;
UShort_t i;
T->Branch("px",&px,"px/F");
T->Branch("py",&py,"px/F");
T->Branch("pz",&pz,"px/F");
T->Branch("random",&randomNum,"random/D");
T->Branch("i",&i,"i/s");
T->SetCircular(20000); //keep a maximum of 20000 entries in memory
for (i = 0; i < 65000; i++) {
r.Rannor(px,py);
pz = px*px + py*py;
randomNum = r.Rndm();
T->Fill();
}
T->Print();
****************************************************************************** *Tree :T : test circular buffers * *Entries : 18977 : Total = 420932 bytes File Size = 0 * * : : Tree compression factor = 1.00 * ****************************************************************************** *Br 0 :px : px/F * *Entries : 18977 : Total Size= 76529 bytes One basket in memory * *Baskets : 0 : Basket Size= 32000 bytes Compression= 1.00 * *............................................................................* *Br 1 :py : px/F * *Entries : 18977 : Total Size= 76529 bytes One basket in memory * *Baskets : 0 : Basket Size= 32000 bytes Compression= 1.00 * *............................................................................* *Br 2 :pz : px/F * *Entries : 18977 : Total Size= 76529 bytes One basket in memory * *Baskets : 0 : Basket Size= 32000 bytes Compression= 1.00 * *............................................................................* *Br 3 :random : random/D * *Entries : 18977 : Total Size= 152469 bytes One basket in memory * *Baskets : 0 : Basket Size= 32000 bytes Compression= 1.00 * *............................................................................* *Br 4 :i : i/s * *Entries : 18977 : Total Size= 38565 bytes One basket in memory * *Baskets : 0 : Basket Size= 32000 bytes Compression= 1.00 * *............................................................................*