/**
 * copyright https://mit-license.org
 * File              : tmp2.cpp
 * Author            : chenxu <chenxu@mail.ustc.edu.cn>
 * Date              : 0 2020-06-21 21:19:15
 * Last Modified Date: 1 2021-05-31 18:48:52
 * Last Modified By  : chenxu <chenxu@mail.ustc.edu.cn>
 */

#include <iostream>
using namespace std;
#include <TFile.h>
#include <TTree.h>
#include <ROOT/RDataFrame.hxx>
#include <TSystem.h>
using namespace ROOT;

class xy_t{
	public:
		double x;
		double y;

		xy_t():x(-1),y(-1){}
		~xy_t(){};
		ClassDef(xy_t,1);
};

void tmp2()
{
	xy_t xy;
	{
		TFile * f1 = new TFile("f1.root", "RECREATE");
		TTree * t1 = new TTree("t1", "t1");
		t1->Branch("xy", &xy);
		xy.x = xy.y = 1;
		t1->Fill();
		t1->Write();
		f1->Close();
	}
	{
		TFile * f1 = new TFile("f2.root", "RECREATE");
		TTree * t1 = new TTree("t1", "t1");
		t1->Branch("xy", &xy);
		xy.x = xy.y = 1;
		t1->Fill();
		t1->Write();
		f1->Close();
	}

	RDataFrame aData("t1", "f*.root");
	aData.Snapshot("t1", "o1.root", {"x"});
//	aData.Snapshot("t1", "o1.root");

	RDataFrame aData2("t1", "o1.root");
	aData2.Foreach([](double x){cout<<x<<endl;}, {"x"});
}