hist039_TH2Poly_usa.C

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/// \file
/// \ingroup tutorial_hist
/// \notebook -js
/// \preview This tutorial illustrates how to create an histogram with polygonal
/// bins (TH2Poly), fill it and draw it using the `col` option. The initial data
/// are stored in TMultiGraphs. They represent the USA map. Such histograms can
/// be rendered in 3D using the option `legogl`.
///
/// The initial data have been downloaded from: http://www.maproom.psu.edu/dcw/
/// This database was developed in 1991/1992 and national boundaries reflect
/// political reality as of that time.
///
/// \macro_code
/// \macro_image
///
/// \date February 2024
/// \author Olivier Couet
 
void hist039_TH2Poly_usa()
{
   Int_t i, bin;
   const Int_t nx = 48;
   const char *states[nx] = {
      "alabama",      "arizona",      "arkansas",       "california",    "colorado",      "connecticut",   "delaware",
      "florida",      "georgia",      "idaho",          "illinois",      "indiana",       "iowa",          "kansas",
      "kentucky",     "louisiana",    "maine",          "maryland",      "massachusetts", "michigan",      "minnesota",
      "mississippi",  "missouri",     "montana",        "nebraska",      "nevada",        "new_hampshire", "new_jersey",
      "new_mexico",   "new_york",     "north_carolina", "north_dakota",  "ohio",          "oklahoma",      "oregon",
      "pennsylvania", "rhode_island", "south_carolina", "south_dakota",  "tennessee",     "texas",         "utah",
      "vermont",      "virginia",     "washington",     "west_virginia", "wisconsin",     "wyoming"};
   Double_t pop[nx] = {4708708,  6595778, 2889450,  36961664, 5024748, 3518288,  885122,  18537969, 9829211, 1545801,
                       12910409, 6423113, 3007856,  2818747,  4314113, 4492076,  1318301, 5699478,  6593587, 9969727,
                       5266214,  2951996, 5987580,  974989,   1796619, 2643085,  1324575, 8707739,  2009671, 19541453,
                       9380884,  646844,  11542645, 3687050,  3825657, 12604767, 1053209, 4561242,  812383,  6296254,
                       24782302, 2784572, 621760,   7882590,  6664195, 1819777,  5654774, 544270};
 
   auto usa = new TCanvas("USA", "USA");
   usa->ToggleEventStatus();
   Double_t lon1 = -130;
   Double_t lon2 = -65;
   Double_t lat1 = 24;
   Double_t lat2 = 50;
   auto p = new TH2Poly("Lower48", "Lower 48 Population (2009);Latitude;Longitude", lon1, lon2, lat1, lat2);
 
   const auto fileName = "usa.root";
   const auto fileNameUrl = "http://root.cern/files/usa.root";
   if(gSystem->AccessPathName(fileName))
      TFile::Cp(fileNameUrl, fileName);
 
   auto f = TFile::Open(fileName);
 
   if (!f) {
      printf("Cannot access %s. Is internet working ?\n", fileName);
      return;
   }
 
   // Define the TH2Poly bins.
   TMultiGraph *mg;
   TKey *key;
   TIter nextkey(gDirectory->GetListOfKeys());
   while ((key = (TKey *)nextkey())) {
      TObject *obj = key->ReadObj();
      if (obj->InheritsFrom("TMultiGraph")) {
         mg = (TMultiGraph *)obj;
         bin = p->AddBin(mg);
      }
   }
 
   // Fill TH2Poly, with capital letters for the states names
   for (i = 0; i < nx; i++)
      p->Fill(states[i], pop[i]);
 
   gStyle->SetOptStat(0);
   p->Draw("colz textn");
 
   // Add the reference for the population
   TLatex pupulationRef(-128, 27, "#scale[.55]{#splitline{Source:}{http://eadiv.state.wy.us/pop/st-09est.htm}}");
   pupulationRef.DrawClone();
}