TTree & TF1 / strings

ROOT
1

Hi Everyone!

I probably have a very simple question for you experts, but nevertheless i have not found the answer to it myself the entire day:

I am trying to simply save a set of TF1 and one list of strings for each TF1 in a tree, like this:

>file >tree1 >TF1_1 >list_1 (for example ["x","y","z"]) >TF1_2 >list_2 (for example ["x","y","z"]) >tree2 >TF1_1 >list_1 (for example ["x","y","z"]) >TF1_2 >list_2 (for example ["x","y","z"])

The problem is: I have no clue, how to do this. I found many tutorials on writing trees, but none could help me. I thought i found the solution with this a = ROOT.TF1("g","gaus",0,10) a.SetParameters(2,4,6) tree = ROOT.TTree( 'testTree', 'Test histogram tree' ) tree.Branch('fun_branch','TF1',a) for the TF1, but somehow i do not store the TF1 but the class of the TF1.

Thanks in advance,

Daniel

2

Hi,

did you call tree.Write() before closing the file? Otherwise, give a full example that fails, so that I can debug it. Beyond that, all I can do is refer to the documentation/tutorials that you have already found.

Cheers,
Wim

3

Hi! Yes I wrote the file. Sry - I made a new exampleCode. I know, this is really basic stuff, but somehow i don’t find the right method for me in any tutorials / examples. All I can find is how to save events in trees or this type of storing i show here, and nowhere i can find how to store lists.

    outputFile=ROOT.TFile("test" + ".root", "RECREATE")
    a = ROOT.TF1("g","gaus",0,10)
    a.SetParameters(2,4,6)
    tree = ROOT.TTree( 'testTree', 'Test histogram tree' )
    tree.Branch('fun_branch','TF1',a)
    outputFile.Write()
    outputFile.Close()

Sorry and Thanks,
Daniel

4

Daniel,

looks like you’re missing a tree.Fill(), before the ‘outputFile.Write()’ line. You need to call ‘tree.Fill()’ for every event/entry.

HTH,
Wim

5

Hi Wim!

tree.Fill() does not change the appearance of the fun_branch in the TFile somehow. It was the same with and without tree.Fill().

Cheers, Daniel!

6

Daniel,

certainly you need ‘tree.Fill()’. It is guaranteed NOT to work w/o that.

With Fill, the code works fine for me.

Not sure what you are looking at for “appearance of the fun_branch”. Try first the file size between w/ and w/o Fill, to see that something at least is being stored.

Cheers,
Wim