// a macro to read in xy data from a file and make a plot
// First run root, then
//  .L draw_XYdata.C
//  draw()
//
//  At prompt, enter input file name (e.g., XYdata.txt).
//  Generalized as needed.

#include "Riostream.h"
void draw() {

  gROOT->Reset();

// first make a canvas and a 2D histogram for the axes

  TCanvas* canvas = new TCanvas("canvas", "canvas", 10, 10, 500, 500);
  canvas->SetFillColor(0);
  canvas->SetBorderMode(0);  
  canvas->SetFrameBorderMode(0);   // need this to turn off red hist frame!

  gROOT->SetStyle("Plain");
  canvas->UseCurrentStyle();

  gPad->SetLeftMargin(0.15);
  gPad->SetRightMargin(0.05);
  gPad->SetTopMargin(0.07);
  gPad->SetBottomMargin(0.17);

  gStyle->SetOptStat(0);
  gStyle->SetTitleBorderSize(0);
  gStyle->SetTitleSize(0.04);

  gStyle->SetTextFont(42);
  gStyle->SetTextSize(0.04);
  gStyle->SetTitleFont(42, "hxy");    // for histogram and axis title
  gStyle->SetLabelFont(42, "xyz");    // for axis labels (values)

  gStyle->SetTitleOffset(0.8, "h");        // what does this do?
  gStyle->SetTitleX(0.15);
  gStyle->SetTitleY(0.99);

  gROOT->ForceStyle();

  // can make histogram or alternatively use the histograms automatically
  // connected to the TF1 or TGraph objects

  double xMin = 0.;
  double xMax = 10.;
  double yMin = 0.;
  double yMax = 10.;
  TH2F* axhist = new TH2F("axhist", "title", 10, xMin, xMax, 10, yMin, yMax);
  axhist->SetTitle("");
  axhist->SetXTitle("x");
  axhist->SetYTitle("y");

  double u[10];
  double x[10][500];

  // Read in data from file and insert in TTree

  TString fileName;
  cout << "Enter file name: ";
  cin >> fileName;

  ifstream inFile;
  inFile.open(fileName);
  if (inFile.fail()) { 
    cout << "Couldn't open file!" << endl;
    exit(1); 
  }

  bool readLine = true;
  int lineNum = 0;
  int ncol;
  while ( readLine ){

    TString line;
    stringstream ss;
    line.ReadLine(inFile);
    readLine = inFile.good();

    if ( readLine ) {

      TString firstChar = line(0,1);
      bool useLine = firstChar != "#";

      if ( useLine ){

        int i = 0;
        stringstream ss;
        ss << line;              // put whole line into ss
        TString token;
        bool getToken = true;

        while ( getToken ) {
          ss >> token;           // extracts one token
          if ( token.Length() > 0 ) {
            u[i] = token.Atof();
            i++;
          } 
          else {
            getToken = false;
          }
        }             // getToken
        ncol = i;  

        for (int i=0; i<ncol; i++){
          x[i][lineNum] = u[i];
        }
        lineNum++;

      }               // useLine

    }         // readLine

  }           // readLine

  int n = lineNum;
  inFile.close();

  //  for (int i=0; i<n; i++){
  //    cout << i << "  " << x[0][i] << "  " << x[1][i] << "  " 
  //    << x[2][i] << endl;
  //  }

  TGraph* tg1 = new TGraph(n, x[0], x[1]);
  TGraph* tg2 = new TGraph(n, x[0], x[2]);

  TAxis* xa = axhist->GetXaxis();
  TAxis* ya = axhist->GetYaxis();

  xa->SetTitleOffset(1.4);    //  factor multiplies default offset
  ya->SetTitleOffset(1.4);

  xa->SetLabelOffset(0.015);
  ya->SetLabelOffset(0.015);

  xa->SetTickLength(0.015);  // default  = 0.03
  ya->SetTickLength(0.015);  // default  = 0.03

  xa->SetTitleSize(0.04);
  ya->SetTitleSize(0.04);

  //  gPad->SetLogx(1);
  //  xa->SetLimits(90., 700.);

  xa->SetNdivisions(-5); // negative value should force number of divisions?
  ya->SetNdivisions(-5);

  xa->SetLabelSize(0.04);
  ya->SetLabelSize(0.04);


  // Draw axes and then add stuff

  // kDot=1, kPlus, kStar, kCircle=4, kMultiply=5,
  // kFullDotSmall=6, kFullDotMedium=7, kFullDotLarge=8,
  // kFullCircle=20, kFullSquare=21, kFullTriangleUp=22,
  // kFullTriangleDown=23, kOpenCircle=24, kOpenSquare=25,
  // kOpenTriangleUp=26, kOpenDiamond=27, kOpenCross=28,
  // kFullStar=29, kOpenStar=30


  axhist->Draw();

  tg1->SetLineColor(1);
  tg1->SetLineWidth(2);
  tg1->SetLineStyle(1);
  tg1->SetMarkerColor(1);
  tg1->SetMarkerSize(0.8);
  tg1->SetMarkerStyle(20);
  tg1->Draw("L");              // or P for points

  tg2->SetLineColor(2);
  tg2->SetLineWidth(2);
  tg2->SetLineStyle(2);
  tg2->SetMarkerColor(2);
  tg2->SetMarkerSize(0.8);
  tg2->SetMarkerStyle(22);
  tg2->Draw("L,same");

  TLegend* leg = new TLegend(0.2, 0.75, 0.5, 0.9); // x1, y1, x2, y2
  leg->SetTextSize(0.04);
  leg->SetBorderSize(0);
  leg->SetFillColor(0);
  leg->AddEntry(tg1, "curve 1", "l");  // l for line, f for box, p for point
  leg->AddEntry(tg2, "curve 2", "l");
  leg->Draw();

  TLatex* tl = new TLatex();
  tl->SetTextAlign(11);
  tl->SetTextSize(0.04);
  tl->SetTextFont(42);
  tl->SetNDC();
  tl->DrawLatex(.7, 0.83, "A label");  

  TPostScript psfile("plot.eps", 113);     // 113 makes eps
  canvas->Draw();
  psfile.Close();
  // canvas->Print("plot.gif", "gif");

}