Reading Histogram from a Root File : Error in <TBufferFile::ReadClassBuffer> ; Error in <TBufferFile::CheckByteCount>

[ricfregian]

Hi rooters,
I’m simply trying to read a histogram of a root file:

   TFile *f = new TFile("/minerva/app/users/gianfred/cmtuser/Minerva_v21r1p1_NX/AnalysisFramework/External/GENIEXSecExtract/cmt/XSec_TEST_actual.root");
  if(f->IsOpen()) printf ("File opened succesfully\n");

   TH2D* u_2DxsecHist = (TH2D*)f->Get("iron_x_vs_Q2Exp_full_dis2D_xsec");
   u_2DxsecHist->Draw();

but it’s not displaying the histogram and I get these errors:

File opened succesfully
Error in <TBufferFile::ReadClassBuffer>: Could not find the StreamerInfo for version 4 of the class TH1, object skipped at offset 95
Error in <TBufferFile::CheckByteCount>: object of class TH1 read too few bytes: 2 instead of 26855

I’m using:
ROOT Version 5.34/36
Platform, compiler gcc version 4.9.3 (GCC)

Any will help will be appreciated.

[pcanal]

Hi,

This is odd and usually indicates that the file is somehow corrupted (might not have been closed properly). The file would also be quite old since v5-08-00 is the first release with v5 of TH1 (So the file/data has been written with a ROOT released before 2005.

Cheers,
Philippe

[Wile_E_Coyote]

Try:

rootls -l /minerva/app/users/gianfred/cmtuser/Minerva_v21r1p1_NX/AnalysisFramework/External/GENIEXSecExtract/cmt/XSec_TEST_actual.root | grep iron_x_vs_Q2Exp_full_dis2D_xsec