TTree::AutoSave() question

ROOT
1

Consider the following unnamed macro:

{
TFile f(“test.root”,“recreate”);
TTree* tree=new TTree(“test”,“test”);
Int_t a;
tree->Branch(“a”,&a,“a/I”);
for ( int i = 0 ; i <1000000 ; i++)
{
a=i;
tree->Fill();
if ( i % 1000 == 1) tree->AutoSave(“SaveSelf”);
}
f.Write();
f.Close();
}

The resulting TFile has two test TTrees with different cycles: 1000 and 1001.

From Phhilippe’s answer to post: root.cern.ch/phpBB2/viewtopic.php?t=559

I understand that the tree with cycle 1000 is saved by the last AutoSave (happening at event 999001), and the cycle 1001 is created by f.Write() at event 999999.
I wonder why, then, the number of entries in the TTrees is, for both cases, 999999.

2

I cannot reproduce your problem. After having run your script, I do:

root [0] TFile f("test.root") root [1] .ls TFile** test.root TFile* test.root KEY: TTree test;1001 test KEY: TTree test;1000 test root [2] TTree *T1000 = (TTree*)f.Get("test;1000") root [3] T1000.GetEntries() (const Long64_t)999002 root [4] TTree *T1001 = (TTree*)f.Get("test;1001") root [5] T1001.GetEntries() (const Long64_t)1000000

Rene

3

Dear Rene,
thanks for the lines of code, I was wrong.
I was inspecting the trees using the TBrowser and starting a tree viewer.
I think that the tree viewer always attaches to the tree with the largest cycle number, I was starting the viewer for cycle 1000 and getting 999999 events (from cycle 1001).
Is this correct?

Andrea

4

Andrea,

I cannot reproduce this problem. Could you clarify all your steps?

Rene

5

I start root with:

root -l test.root
root[0]new TBrowser

I then open the root file, I can see the two trees with cycle 1000 and 1001.
I select “test;1000” right clicking on it and then select start viewer (see screenshot.png).

TreeViewer reports: “First entry: 0 Last entry: 999999” (see screenshot1.png)

Drawing leaf a also reports 1M entries (screenshot2.png).

Hope this clarify,
Andrea

screenshot2.png708×528 5.79 KB




screenshot.png808×528 14.2 KB

6

Hi,

Currently, the TBrowser always load the latest version (highest cycle) no matter which one you click on.

Cheers,
Philippe.

7

Hi,

FYI, this should be fixed in svn rev 30090

Cheers, Bertrand.