How to extract data from root file?

[_ERICA]

I got root file from geant4 so I could see histograms but I want to see the data about the histogram.
Could you please help me to export the data as a .txt or something to be able to analyse it in other programs?

TFile file = new TFile(“whitebeam.root”, “read”); TH1D h1 = (TH1D*) file -> Get(“1”); h1 -> Print(“all”); > aaa.txt

I’ve tried and tried to follow so many similar things like that, but couldn’t get any.
Please help me to get it.

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ROOT Version: Not Provided
Platform: Not Provided
Compiler: Not Provided

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[Wile_E_Coyote]

What you try to use works with ROOT 5 only.
With ROOT 6, you need to replace “> aaa.txt” with:

root [...] .> aaa.txt
root [...] h1->Print("all");
root [...] .>

[_ERICA]

I tried it but It said “error in : Trying to dereference null pointer or trying to call routine taking non-null arguments.”.

Could you tell me what I should do to solve this problem?

[dastudillo]

Are you sure the histogram name in the file is “1”? Check with

 .ls

or

 f->ls()

after opening the file.

[_ERICA]

[class] [name];[cycle number]
so it name is histo??

[_ERICA]

it’s also the same root file. but the name looks different.

[dastudillo]

try

 TH1D *h1 = (TH1D*) file -> Get("histo/h1");

[_ERICA]

I did like that.

[_ERICA]

But the .txt file looks like this…

[dastudillo]

Print h1, not histo.

[_ERICA]

I did it, but I got an error message… Did I something wrong??

[Wile_E_Coyote]

TH1D *h1; file->GetObject("histo/h1.1", h1);

[_ERICA]

Thank you so much.

Now I got it.

Thanks again!