Fill vector<> from vector< vector< >> into TTree

ROOT
1

Hi rooters,

I tried to save several vector from a vector< vector> into a root TTree. It is nessesary to save each vector into this tree seperately, to be able to use the features from TTreeViewer. Here is the smallest (not) working macro:

[code]//macro to save vector in TTree
//std. c includes
#include <stdlib.h>
#include <stdio.h>
#include

//root includes
#include “TTree.h”
#include “TFile.h”
#include “TBranch.h”

void FillTTree() {
//init vectors
std::vector *time_signal = new std::vector();
std::vector <vector > *waveform_vector = new std::vector <vector >();
//open file
f = new TFile(“Data.root”, “RECREATE”);
//define TTree
waveforms = new TTree(“waveforms”, “Tree containing Acqiris waveforms”);
waveforms->Branch(“time”,“vector”, &time_signal,1000,0);
waveforms->Branch(“channel1”,“vector”, &waveform_vector->at(0),1000,0);
waveforms->Branch(“channel2”,“vector”, &waveform_vector->at(1),1000,0);
waveforms->Branch(“channel3”,“vector”, &waveform_vector->at(2),1000,0);
waveforms->Branch(“channel4”,“vector”, &waveform_vector->at(3),1000,0);

//fill TTree
for (int events=0; events<1000; events++)
{ for (int i=0; i<4; i++)
{ waveform_vector->push_back(vector ());
for (int j=0; j<1000; j++)
{ if (i==0) time_signal->push_back(j);
waveform_vector->at(i).push_back((i+1)*j);
}
}
waveform1_vector = &waveform_vector->at(0);
waveform2_vector = &waveform_vector->at(1);
waveform3_vector = &waveform_vector->at(2);
waveform4_vector = &waveform_vector->at(3);
waveforms->Fill();
time_signal->clear();
waveform_vector->clear();
}
waveforms->Write();
f->Close();
}
[/code]
The root interpreter returns:
Error: Symbol #include is not defined in current scope FillTTree.cpp:29:
Error: Symbol exception is not defined in current scope FillTTree.cpp:29:
Syntax Error: #include FillTTree.cpp:29:
Error: Symbol G__exception is not defined in current scope FillTTree.cpp:29:
Error: type G__exception not defined FILE: FillTTree.cpp LINE:29
*** Interpreter error recovered ***

If one pass the pointer of a vector element of this vector< vector> to another 1d vector and saves this into the root Tree, everything is fine.
Is it possible to define a TTree in that way and pass such an Element to a Branch, like it is shown in the posted code??

Cheers
Toni

2

Hi Toni,

For this:waveforms->Branch("channel1","vector<float>", &waveform_vector->at(0),1000,0);the code must insure/guarantee that the waveform_vector is never resized. It should work properly if you do:waveforms_vector.resize(4); before creating the branches. It also means that you must remove the line:waveform_vector->push_back(vector<float> ());which does provoke a resizing of the waveform_vector (i.e. as the code is setup original the address passed to Branch are actually invalid/random).

Cheers,
Philippe.

1 Like
3

Hello Philippe,

thank you for your fast reply and the hints for my macro. I have removed the push_back(vector ()) line and now resizing the vector before I create the Branches. The resulting code is now:

[code]//macro to save vector in TTree
//std. c includes
#include <stdlib.h>
#include <stdio.h>
#include

//root includes
#include “TTree.h”
#include “TFile.h”
#include “TBranch.h”

void FillTTree() {
std::vector *time_signal = new std::vector();
std::vector <vector > *waveform_vector = new std::vector <vector >();

waveform_vector->resize(4);

f = new TFile("Data.root", "RECREATE");
waveforms = new TTree("waveforms", "Tree containing Acqiris waveforms");

waveforms->Branch("time","vector<float>", &time_signal,1000,0);
waveforms->Branch("channel1","vector<float>", &waveform_vector->at(0),1000,0);
waveforms->Branch("channel2","vector<float>", &waveform_vector->at(1),1000,0);
waveforms->Branch("channel3","vector<float>", &waveform_vector->at(2),1000,0);
waveforms->Branch("channel4","vector<float>", &waveform_vector->at(3),1000,0);

for (int events=0; events<1000; events++)
{   for (int i=0; i<4; i++)
    {   for (int j=0; j<1000; j++)
        {   if (i==0) time_signal->push_back(j);
            waveform_vector->at(i).push_back((i+1)*j);
        }
    }
    waveforms->Fill();
    time_signal->clear();
    waveform_vector->at(0).clear();
    waveform_vector->at(1).clear();
    waveform_vector->at(2).clear();
    waveform_vector->at(3).clear();
}
waveforms->Write();
f->Close();

}

[/code]

The return of the Interpreter is still:
Error: Symbol #include is not defined in current scope FillTTree.cpp:38:
Error: Symbol exception is not defined in current scope FillTTree.cpp:38:
Syntax Error: #include FillTTree.cpp:38:
Error: Symbol G__exception is not defined in current scope FillTTree.cpp:38:
Error: type G__exception not defined FILE:FillTTree.cpp LINE:38
*** Interpreter error recovered **

What’s wrong??

Thanks again.
Toni

4

Hi Toni,

I recommend you try:valgrind root.exe -b -l -q FillTree.C+ which will give us a better clue on what the problem is.

Cheers,
Philippe.

5

Modify your code:

// ... TFile *f = new TFile("Data.root", "RECREATE"); TTree *waveforms = new TTree("waveforms", "Tree containing Acqiris waveforms"); // ...
Then, try “root [0] .x FillTTree.cpp++”. It works for me.
Also “root [0] .x FillTTree.cpp” works.

6

Thank you both again.

I think this was a classical “version problem”. There is root 5.26.00 installed here and now I tried it on 5.28.00 and it works! There was a change in 5.28.00 I think, which adresses the TTree, right? I think, I read about it in another post.

The quick support in this forum is very great. Thank you.

Cheers
Toni

7

Hi Toni,

Very possible. Please note that in newer version of ROOT, you can use:waveforms->Branch("channel1",&waveform_vector->at(0),1000,0);which automatically detect the data type.

Cheers,
Philippe.