void piechart()
{
   Float_t vals[] = {.2, 1.1, .6, .9, 2.3};
   Int_t colors[] = {2, 3, 4, 5, 6};
   Int_t nvals = sizeof(vals) / sizeof(vals[0]);

   TCanvas *cpie = new TCanvas("cpie", "TPie test", 700, 700);
   cpie->Divide(2, 2);

   TPie *pie1 = new TPie("pie1", "Pie with offset and no colors", nvals, vals);
   TPie *pie2 = new TPie("pie2", "Pie with radial labels", nvals, vals, colors);
   TPie *pie3 = new TPie("pie3", "Pie with tangential labels", nvals, vals, colors);
   TPie *pie4 = new TPie("pie4", "Pie with verbose labels", nvals, vals, colors);

   cpie->cd(1);
   pie1->SetAngularOffset(30.);
   pie1->SetEntryRadiusOffset(4, 0.1);
   pie1->SetRadius(.35);
   pie1->Draw("3d");

   cpie->cd(2);
   pie2->SetEntryRadiusOffset(2, .05);
   pie2->SetEntryLineColor(2, 2);
   pie2->SetEntryLineWidth(2, 5);
   pie2->SetEntryLineStyle(2, 2);
   pie2->SetEntryFillStyle(1, 3030);
   pie2->SetCircle(.5, .45, .3);
   pie2->Draw("rsc");

   cpie->cd(3);
   pie3->SetY(.32);
   pie3->GetSlice(0)->SetValue(.8);
   pie3->GetSlice(1)->SetFillStyle(3031);
   pie3->SetLabelsOffset(-.1);
   pie3->Draw("3d t nol");
   TLegend *pieleg = pie3->MakeLegend();
   pieleg->SetY1(.56);
   pieleg->SetY2(.86);

   cpie->cd(4);
   pie4->SetRadius(.2);
   pie4->SetLabelsOffset(.01);
   pie4->SetLabelFormat("#splitline{%val (%perc)}{%txt}");
   pie4->Draw("nol <");
}