The type of TTree parameter

Newbie
1

Hi guys, I have created a TTree to write some double number(their name is Fdata) in it and then read them. when I define Fdata as integer then the program print the integer part correctly, but if I define it as double parameter the program just print zero. How can I print these double number correctly?
The code is :

{

TFile* MyFile = new TFile("Badom.root");
	TTree* TREE = (TTree*)MyFile->Get("MY TREE");
	
	int Fdata = 0;

	TREE->SetBranchAddress("FDATA", &Fdata);

}

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

2

Your code doesn’t do anything. Could you post the full code?

3

That was just a part of the code.I have created ROOTFile already and named it Badom.root. Double numbers wrote in root file and I read them here.

{
double FinalData[NREvents][NrNSamplesPerEvent];


	TFile* MyFile = new TFile("Badom.root");
	TTree* TREE = (TTree*)MyFile->Get("MY TREE");
	
	int Fdata = 0;

	TREE->SetBranchAddress("FDATA", &Fdata);


	cout << "Analyzing file ... " << endl << '\n';

	Long64_t NEntries = TREE->GetEntries();
	Long64_t EVENT_it = 0, SAMPLE_it = 0;
	cout << "NrEntries: " << NEntries << endl;
	
	for (Long64_t j = 0; j < NEntries; j++) {
		Index++;
		TREE->GetEntry(j);
		FinalData[EVENT_it][SAMPLE_it] = Fdata;
		SAMPLE_it += 1;
		cout <<"Event is : "<<'\t'<< EVENT_it <<'\t'<<"sample is : "<<'\t'<< SAMPLE_it <<'\t'<<"data is:"<<'\t'<< Fdata << endl;
}
4

If you wrote double values, why do you want to read integers then?

5

No, I wanna to read them as double number, but when I define Fdate as a double parameter , the code just print zero, I mean the code print wrong number. But when I define Fdata as integer, the code print the integer part correctly. The Fdata parameter can be any type? If it can has double type so what is wrong? why I cannot print double number correctly?

6

What is the output of TREE->Print()?

7

Double numbers that stored in root file.I print them at cout line.

8

I was expecting a screenshot (copied/pasted), something like this:

root [1] t1->Print()
******************************************************************************
*Tree    :t1        : a simple Tree with simple variables                    *
*Entries :    10000 : Total =          243611 bytes  File  Size =     180826 *
*        :          : Tree compression factor =   1.34                       *
******************************************************************************
*Br    0 :px        : px/F                                                   *
*Entries :    10000 : Total  Size=      40615 bytes  File Size  =      37333 *
*Baskets :        2 : Basket Size=      32000 bytes  Compression=   1.08     *
*............................................................................*
*Br    1 :py        : py/F                                                   *
*Entries :    10000 : Total  Size=      40615 bytes  File Size  =      37310 *
*Baskets :        2 : Basket Size=      32000 bytes  Compression=   1.08     *
*............................................................................*
*Br    2 :pz        : pz/F                                                   *
*Entries :    10000 : Total  Size=      40615 bytes  File Size  =      36663 *
*Baskets :        2 : Basket Size=      32000 bytes  Compression=   1.09     *
*............................................................................*
*Br    3 :random    : random/D                                               *
*Entries :    10000 : Total  Size=      80722 bytes  File Size  =      54555 *
*Baskets :        3 : Basket Size=      32000 bytes  Compression=   1.47     *
*............................................................................*
*Br    4 :ev        : ev/I                                                   *
*Entries :    10000 : Total  Size=      40615 bytes  File Size  =      14155 *
*Baskets :        2 : Basket Size=      32000 bytes  Compression=   2.84     *
*............................................................................*
root [2]

Anyway, can you post your root file?

9

This is the root file:
Badom.root (792.7 KB)

10

I don’t see anything in your file:

root [0] TFile *f = TFile::Open("Badom.root")
(TFile *) 0x2e755c0
root [1] .ls
TFile**         Badom.root      EXAMPLE
 TFile*         Badom.root      EXAMPLE
root [2] f->ls()
TFile**         Badom.root      EXAMPLE
 TFile*         Badom.root      EXAMPLE
root [3]
11

Test this again please :
Badom.root (206.0 KB)

12

Your FDATA variable is an integer (Fdata/I):

root [4] t->Print()
******************************************************************************
*Tree    :MY TREE   : Tree to save guassian data                             *
*Entries :   499800 : Total =         2005877 bytes  File  Size =     151811 *
*        :          : Tree compression factor =  13.29                       *
******************************************************************************
*Br    0 :FDATA     : Fdata/I                                                *
*Entries :   499800 : Total  Size=    2005490 bytes  File Size  =     150803 *
*Baskets :       63 : Basket Size=      32000 bytes  Compression=  13.29     *
*............................................................................*
root [5]
13

So what should I write instead Fdata/I ?

14

When you create the branch, create it with /F, like “Fdata/F”. If you read the TTree documentation, or look at the tree tutorials, you will see how to properly create a tree with branches in the format you want. I would also suggest to start with the ROOT Primer

15

Thank you so much :rose:

1 Like
16

How it is defined the variable in the TTree ?
What is the result of TTree->Print() ?

17

Thanks @moneta, the issue is already solved…