example-readoaanalysis

This package provides a simple example for new T2K students to read ND280 OA analysis files using only ROOT and no other external libraries.

Compiling and Running the Example Analysis

Before you start you will need an oaAnalysis input file. The scripts are hard coded to look for a file named "test.oaanalysisfile.root" in the current working directory. You should make sure this file exists, or edit the scripts to point to a real file before proceeding.

There are two steps involved. First you must generate the libraries needed to read the oaAnalysis file. This is done with the TFile::MakeProject method. This is done by running the makelib.C script:

root -l makelib.C

The "-l" option prevents the annoying ROOT splash screen. This script should create a directory "liboaanalysis" containing the header files and library that you will need. If it worked you should see that it contains a file "liboaanalysis/liboaanalysis.so". You are now ready to analyse an oaAnalysis file.

You can run the example analysis code with:

root -l run.C

This script loads the libraries that were generated in the previous step, compiles "analysis.C" and runs the method "analysis()". "analysis.C" contains a simple analysis script that loops over global recon objects and prints information to stdout.

Congratulations, you have successfully run your first oaAnalysis analysis!

Reading Files Interactively

You can also read analysis files in an interactive ROOT session.

root -l 

To view to file contents in a GUI, in an interactive session do:

[0] gSystem->Load("liboaanalysis/liboaanalysis.so"); // load libraries
[1] TBrowser b;

From the TBrowser window you can double click on the analysis file to open it.

You can make simple plots using the TTree::Draw command.

[2] TFile* f = new TFile("test.oaanalysisfile.root");
[3] TTree* t = (TTree*) f->Get("ReconDir/TrackerECal");
[4] t->Draw("ReconObject.PID_LLR_MIP_EM");