#include "TFile.h"
#include "TH1.h"
#include "TH2.h"
#include "TChain.h"
#include "TTree.h"
#include "TLeaf.h"
#include <ROOT/RDataFrame.hxx>

#define UpdateEvents    2000

//using namespace std;

void GetValue(const char *filename = "eu152_11july_afterGlitch.002", const char *treename = "RoseNIAS")
{
ROOT::EnableImplicitMT();

	const char* nmHis[20];
	Int_t NoPara;
	Long64_t nentries;

        TChain *fChain = new TChain(treename);
        fChain->AddFile(filename);
        TObjArray*obj = fChain->GetListOfBranches();
        NoPara = obj->GetEntries();         //Number of parameters in Tree and hence in experiment
        nentries = fChain->GetEntriesFast();      // Number of events in the Tree

	ROOT::RDataFrame df(treename, filename);
	std::vector<ROOT::RDF::RResultPtr<TH1D>> histos;
	for (const std::string &col : df.GetColumnNames()) {
		auto h = df.Histo1D<double>(col);
		histos.push_back(h);
		
}
histos[0]->Draw();	// !!!!!This DOES NOT WORK!!!!

histos[0]->GetMean();	// !!!!!This DOES NOT WORK!!!!


// Computation has been booked but it has not started yet.
// The first time you access one of the histograms,
// all of them will be filled in a single event loop

//cout << "\n Total Number Entries in the TChain is:\t" << nentries << endl;

//printf ("EVENTS = %8d....\n", nentries);
}