CERN_Project_Plotting/merge_root_files.C at master · larsb-p/CERN_Project_Plotting · GitHub

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////////////////////////////////////////////////////////////////////////////////////////////////////

// File: merge_root_files.C

// Script to merge .root-files in 'txt_files/root_path_file.root'.
// It takes

//      * 'txt_files/root_path_file.txt'
//      * 'root_files/file_*.root'

// as inputs to create a new .root-file called 'merged_file.root' in the 'root_files/' directory.
// After starting root, this script can be run by typing: .x merge_root_files.C()

// Author: Lars Bathe-Peters <lars.bathe-peters@cern.ch>
// CERN Summer Student Programme 2019

////////////////////////////////////////////////////////////////////////////////////////////////////


void merge_root_files() {

        TChain chain("data");
        TChain chain2("corrections");
        std::ifstream input_root_files("txt_files/root_path_file.txt");

        if (input_root_files.is_open()) {
                cout << "File" << " has been opened" << endl;
        }
        else {
                cout << "NO FILE HAS BEEN OPENED" << endl;
                exit(0);
        }

        std::string line;

        while ( std::getline( input_root_files, line ) ) {
                chain.Add( line.c_str() );
                chain2.Add( line.c_str() );
                cout << "line " <<  line << endl;
        }

        TFile* f = new TFile( "root_files/merged_file.root", "RECREATE" );

        chain.CloneTree( -1, "fast" );
        chain2.CloneTree( -1, "fast" );
        f->Write();

        return 0;
}