Reading TTrees which contain classes returning std:vector in Pyroot

I am reading a TTree in pyroot (arborescence attached). I can access all class members which return a constant without problem but I am having issues while accessing a class member that returns a cpp std:: vector. It gives me a segmentation fault (see below).

Here is a code snippet:

mc_particle= rootfile.Get('MCParticle')
pixel_charge= rootfile.Get('PixelCharge')
prop_charge= rootfile.Get('PropagatedCharge')
pixel_hit= rootfile.Get('PixelHit')

for iev in range(0, pixel_hit.GetEntries()):

    pixel_charge_branch= pixel_charge.detector
    pixel_hit_branch= pixel_hit.detector
    mc_particle_branch= mc_particle.detector

    for mc_part in mc_particle_branch:
        print "part:", mc_part.getParticleID()

    for pix_charge in pixel_charge_branch:
        print "charge:", pix_charge.getCharge()

    for pix_hit in pixel_hit_branch:
        print "hit",pix_hit.getSignal() #this works and returns what is expected
        print "local center:",pix_hit.getPixel().getLocalCenter().x() # this also 
        print type(pix_hit.getMCParticles()) # this seg faults (output below)
       #also tried e.g pix_hit.getMCParticles().getParticleID() # this seg faults (output below)

and part of the output is below. As you can see hit and local center are printed out without problem but I get a crash when accessing getMCParticles which returns a std::vector. This getMCParticles method is understood and exists (if I try to access e.g pix_hit.getMCSometthing_not_exsiting it simply gives me an error).

Thanks a lot,

*Tree    :MCParticle: Tree of MCParticle                                     *
*Entries :     5000 : Total =         2130296 bytes  File  Size =     363848 *
*        :          : Tree compression factor =   5.87                       *
*Br    0 :detector  : vector<allpix::MCParticle*>                            *
*Entries :     5000 : Total  Size=    2129857 bytes  File Size  =     362730 *
*Baskets :       68 : Basket Size=      32000 bytes  Compression=   5.87     *
<class 'ROOT.TTree'>
part: 22
part: 11
charge: 1066
hit 1066.0
local center: 0.0

 *** Break *** segmentation violation
[/usr/lib/system/libsystem_platform.dylib] _sigtramp (no debug info)
[<unknown binary>] (no debug info)
[/Applications/root_v6.10.08/lib/] Cppyy::CallO(long, void*, void*, long) (no debug info)
[/Applications/root_v6.10.08/lib/] PyROOT::TCppObjectByValueExecutor::Execute(long, void*, PyROOT::TCallContext*) (no debug info)
[/Applications/root_v6.10.08/lib/] PyROOT::TMethodHolder::CallFast(void*, long, PyROOT::TCallContext*) (no debug info)
[/Applications/root_v6.10.08/lib/] PyROOT::TMethodHolder::CallSafe(void*, long, PyROOT::TCallContext*) (no debug info)
[/Applications/root_v6.10.08/lib/] PyROOT::TMethodHolder::Execute(void*, long, PyROOT::TCallContext*) (no debug info)
[/Applications/root_v6.10.08/lib/] PyROOT::TMethodHolder::Call(PyROOT::ObjectProxy*&, _object*, _object*, PyROOT::TCallContext*) (no debug info)
[/Applications/root_v6.10.08/lib/] PyROOT::(anonymous namespace)::mp_call(PyROOT::MethodProxy*, _object*, _object*) (no debug info)
[/System/Library/Frameworks/Python.framework/Versions/2.7/Python] PyObject_Call (no debug info)
[/System/Library/Frameworks/Python.framework/Versions/2.7/Python] PyEval_EvalFrameEx (no debug info)
[/System/Library/Frameworks/Python.framework/Versions/2.7/Python] PyEval_EvalCodeEx (no debug info)
[/System/Library/Frameworks/Python.framework/Versions/2.7/Python] PyEval_EvalCode (no debug info)
[/System/Library/Frameworks/Python.framework/Versions/2.7/Python] (no debug info)
[/System/Library/Frameworks/Python.framework/Versions/2.7/Python] PyRun_FileExFlags (no debug info)
[/System/Library/Frameworks/Python.framework/Versions/2.7/Python] PyRun_SimpleFileExFlags (no debug info)
[/System/Library/Frameworks/Python.framework/Versions/2.7/Python] Py_Main (no debug info)
[/usr/lib/system/libdyld.dylib] start (no debug info)
[<unknown binary>] (no debug info)
Traceback (most recent call last):
  File "", line 89, in <module>
    print type(ROOT.std(pix_hit.getMCParticles()))
SystemError: vector<const allpix::MCParticle*> allpix::PixelHit::getMCParticles() =>
    problem in C++; program state has been reset

ROOT Version: v6-10-08
_Platform:_MAC OS 10.13
Compiler: clang

it would be easier to debug with a test file :slight_smile: (I think)

here is the macro and the root file. The problem is that one must load a library from an external program (also attached), so don’t think it will run out of the box. Hope it helps in any case.

Sebastien (3.5 KB)

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