/*
#include <vector>;
#include <algorithm>
#include <string>
#include <sstream>
using namespace std;
*/

void root_debug() {
	
	MakeFile();

	TFile * file = new TFile("C:/.../root_debug.root","READ");
	TTree * tree = (TTree*)file->Get("test_tree");

	DrawHistograms(tree);
	//DrawTree(tree);
}

void DrawTree(TTree * tree) {

	const int Nbranch = 10;
	int i;

	TCanvas * c[Nbranch-1];

	for (i = 1; i < Nbranch; ++i) {

		c[i] = new TCanvas();
		c[i]->cd();

		stringstream tmp;
		tmp << "branch_" << i << ":branch_" << 0;
		tree->Draw(tmp.str().c_str(),"","LP");
	}
}

void DrawHistograms(TTree * tree) {

	const int Nbranch = 10;
	TH1F * h[Nbranch-1];
	TCanvas * c[Nbranch-1];

	int i1 = 0, i2 = 1;
	for (int i = i1; i < i2; ++i) {
		stringstream tmp;
		tmp << "branch_" << i;
		h[i-1] = GetHistogram(tree, tmp.str().c_str());
		stringstream tmp2;
		tmp2 << "canvas_" << i;
		c[i-1] = new TCanvas(tmp2.str().c_str(),tmp2.str().c_str());
		c[i-1]->cd();
		h[i-1]->Draw();
		h[i-1]->SetBit(kCanDelete);
	}
}


void MakeFile() {

	TFile * file = new TFile("C:/.../root_debug.root", "UPDATE");
	TTree * tree = new TTree("test_tree", "test_tree");

	int Nbranch = 10, Nentries = 100;
	int i;
	vector<double> x(Nbranch-1);

	for (i = 0; i < Nbranch; ++i) {
		stringstream tmp;
		tmp << "branch_" << i;
		if (i) tree->Branch(tmp.str().c_str(), &x[0] + i  - 1, (tmp.str() +"/D").c_str());
		else tree->Branch(tmp.str().c_str(), &i, (tmp.str() +"/I").c_str());
	}

	for (i = 0; i < Nentries; ++i) {
		for (int k = 0; k < Nbranch - 1; ++k) x[k] = k*100.+ i;
		tree->Fill();
	}
	file->Write();
	cout << "wrote root file" << endl;
}

TH1F * GetHistogram(TTree * tree, const char * branch) {

	double x, xmin = 1.e100, xmax = -1.e100;
	vector<double> xx;
	int n = tree->GetEntries();
	xx.reserve(n);

	tree->SetBranchAddress(branch,&x);
	for (int i=0; i<n; ++i) {
		tree->GetEntry(i);
		xx.push_back(x);
		if (x>xmax) xmax = x;
		if (x<xmin) xmin = x;
	}

	stringstream name;
	name << "hist_" << branch;
	TH1F * h = new TH1F( name.str().c_str(), name.str().c_str(), 20, xmin, xmax );
	h->FillN(n, &xx[0], 0);

	cout << "returning histogram for " << branch << endl;
	return h;
}