Ntuples: unable to read

[Marooz_Malik]

Hi, I have a root file with some tuples. when I open open with TBrowser, it shows values at for example 4 in the figure below.

but when I use a code, or simply Draw it via terminal: TFile f("f0_output_eventsfivetev35.root"); TList *l = (TList*)f.Get("htupList"); TNtuple *t = (TNtuple*)l->FindObject("FqTuple0_ptbin1_cbin0"); t->Draw("Mb");
I get the following with so many values at zero.

What might be the reason??

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ROOT Version: 6.36.000
Built for macosxarm64
From tags/6-36-000@6-36-000

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[yus]

Hi,

could you please share your ROOT file?

[pcanal]

@Marooz_Malik

TList l = (TList)f.Get(“htupList”); TNtuple t = (TNtuple)l->FindObject(“FqTuple0_ptbin1_cbin0”);

This is an unusual way to store the TTree and you may or may not be retrieving what you need/want. What is the result of

f.ls();

Thanks.

[Marooz_Malik]

thanks for the reply. I am attaching the root file cernbox link: CERNBox

[Marooz_Malik]

thanks for the reply. this is how they are stored in the file. I have attached the file

[dastudillo]

If I draw a second time, it works fine

root [0] TFile f("f0_output_eventsfivetev35.root"); TList *l = (TList*)f.Get("htupList"); TNtuple *t = (TNtuple*)l->FindObject("FqTuple0_ptbin1_cbin0");
root [1] t->Draw("Mb");   # shows points at zero
Info in <TCanvas::MakeDefCanvas>:  created default TCanvas with name c1
root [2] t->Draw("Mb");   # all points at 4

It looks like something (pointer?) is not being properly initialised before the first draw.
If I do t->Print() before drawing, the result is even crazier:

root [0] TFile f("f0_output_eventsfivetev35.root"); TList *l = (TList*)f.Get("htupList"); TNtuple *t = (TNtuple*)l->FindObject("FqTuple0_ptbin1_cbin0");
root [1] t->Print()
******************************************************************************
*Tree    :FqTuple0_ptbin1_cbin0: etaphitup0_1_0                                         *
*Entries :    19851 : Total =          481869 bytes  File  Size =      47899 *
*        :          : Tree compression factor =   8.02                       *
******************************************************************************
*Br    0 :Mb        : Float_t                                                *
*Entries :    19851 : Total  Size=      80243 bytes  File Size  =        558 *
*Baskets :        2 : Basket Size=      32000 bytes  Compression= 114.69     *
*............................................................................*
*Br    1 :Av_bcon   : Float_t                                                *
*Entries :    19851 : Total  Size=      80283 bytes  File Size  =       8569 *
*Baskets :        2 : Basket Size=      32000 bytes  Compression=   7.47     *
*............................................................................*
*Br    2 :fq2e      : Float_t                                                *
*Entries :    19851 : Total  Size=      80259 bytes  File Size  =       9792 *
*Baskets :        2 : Basket Size=      32000 bytes  Compression=   6.54     *
*............................................................................*
*Br    3 :fq3e      : Float_t                                                *
*Entries :    19851 : Total  Size=      80259 bytes  File Size  =       9674 *
*Baskets :        2 : Basket Size=      32000 bytes  Compression=   6.61     *
*............................................................................*
*Br    4 :fq4e      : Float_t                                                *
*Entries :    19851 : Total  Size=      80259 bytes  File Size  =       9652 *
*Baskets :        2 : Basket Size=      32000 bytes  Compression=   6.63     *
*............................................................................*
*Br    5 :fq5e      : Float_t                                                *
*Entries :    19851 : Total  Size=      80259 bytes  File Size  =       9654 *
*Baskets :        2 : Basket Size=      32000 bytes  Compression=   6.63     *
*............................................................................*
root [2] t->Draw("Mb");
Info in <TCanvas::MakeDefCanvas>:  created default TCanvas with name c1
root [3]

But drawing a second time, the issue goes away again.

[Wile_E_Coyote]

Try:

cout << t->GetEntry(0) << endl;
cout << t->GetEntry(15955) << endl;
cout << t->GetEntry(15956) << endl;
cout << t->GetEntry(19850) << endl;
cout << t->GetEntry(19851) << endl;

@pcanal Maybe TTree:Draw (and similar) should be protected against “I/O errors”.

@Marooz_Malik For saving multiple trees, instead of a TList, use a TDirectoryFile (i.e., a disk resident TDirectory).

[ferhue]

@Wile_E_Coyote

Maybe TTree:Draw (and similar) should be protected against “I/O errors”.

See [tree] raise error if entry not properly loaded in EvalInstance by ferdymercury · Pull Request #19273 · root-project/root · GitHub

[Marooz_Malik]

@Wile_E_Coyote

@Marooz_Malik For saving multiple trees, instead of a TList, use a TDirectoryFile (i.e., a disk resident TDirectory).

this fixed the issue.