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th2polyUSA.C File Reference

Detailed Description

View in nbviewer Open in SWAN 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.

void th2polyUSA()
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
TCanvas *usa = new TCanvas("USA", "USA");
Double_t lon1 = -130;
Double_t lon2 = -65;
Double_t lat1 = 24;
Double_t lat2 = 50;
TH2Poly *p = new TH2Poly("USA","USA Population",lon1,lon2,lat1,lat2);
TFile *f = TFile::Open("http://root.cern.ch/files/usa.root", "CACHEREAD");
if (!f) {
printf("Cannot access usa.root. Is internet working ?\n");
// Define the TH2Poly bins.
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.
for (i=0; i<nx; i++) p->Fill(states[i], pop[i]);
p->Draw("colz textn");
#define f(i)
Definition RSha256.hxx:104
int Int_t
Definition RtypesCore.h:45
double Double_t
Definition RtypesCore.h:59
#define gDirectory
Definition TDirectory.h:290
R__EXTERN TStyle * gStyle
Definition TStyle.h:412
The Canvas class.
Definition TCanvas.h:23
virtual void ToggleEventStatus()
Toggle event statusbar.
Definition TCanvas.cxx:2446
A ROOT file is a suite of consecutive data records (TKey instances) with a well defined format.
Definition TFile.h:54
static Bool_t SetCacheFileDir(ROOT::Internal::TStringView cacheDir, Bool_t operateDisconnected=kTRUE, Bool_t forceCacheread=kFALSE)
Definition TFile.h:324
static TFile * Open(const char *name, Option_t *option="", const char *ftitle="", Int_t compress=ROOT::RCompressionSetting::EDefaults::kUseCompiledDefault, Int_t netopt=0)
Create / open a file.
Definition TFile.cxx:3997
virtual void Draw(Option_t *option="")
Draw this histogram with options.
Definition TH1.cxx:3073
2D Histogram with Polygonal Bins
Definition TH2Poly.h:66
virtual Int_t Fill(Double_t x, Double_t y)
Increment the bin containing (x,y) by 1.
Definition TH2Poly.cxx:589
virtual Int_t AddBin(TObject *poly)
Adds a new bin to the histogram.
Definition TH2Poly.cxx:222
Book space in a file, create I/O buffers, to fill them, (un)compress them.
Definition TKey.h:28
virtual TObject * ReadObj()
To read a TObject* from the file.
Definition TKey.cxx:750
A TMultiGraph is a collection of TGraph (or derived) objects.
Definition TMultiGraph.h:36
Mother of all ROOT objects.
Definition TObject.h:37
virtual Bool_t InheritsFrom(const char *classname) const
Returns kTRUE if object inherits from class "classname".
Definition TObject.cxx:445
void SetOptStat(Int_t stat=1)
The type of information printed in the histogram statistics box can be selected via the parameter mod...
Definition TStyle.cxx:1589
Olivier Couet

Definition in file th2polyUSA.C.