要求：
打开ROOT文件，MakeClass生成两文件：
(ams) zpw@dell:~/Files/0520_iss$ root ISS_001223.root
------------------------------------------------------------------
| Welcome to ROOT 6.26/10 https://root.cern |
| (c) 1995-2021, The ROOT Team; conception: R. Brun, F. Rademakers |
| Built for linuxx8664gcc on Nov 17 2022, 16:18:00 |
| From tag , 16 November 2022 |
| With |
| Try '.help', '.demo', '.license', '.credits', '.quit'/'.q' |
------------------------------------------------------------------
root [0]
Attaching file ISS_001223.root as _file0...
(TFile *) 0x561bb71cab80
root [1] .ls
TFile** ISS_001223.root
TFile* ISS_001223.root
KEY: TTree t1;1 ISS_001223.root
root [2] t1->MakeClass("iss")
Info in <TTreePlayer::MakeClass>: Files: iss.h and iss.C generated from TTree: t1
(int) 0
root [3] .q
修改 iss.h 对应部分：
Int_t iss::Cut(Long64_t entry)
{
if (!(0.5 < q_trk && q_trk < 1.5)) return -1;
if (!(0.5 < q_tofd && q_tofd < 3)) return -1;
if (!(0. < rig_i && rig_i < 30)) return -1;
if (!(beta_rich >0)) return -1;
if (!(IsNaF == 0)) return -1;
return 1;
}
修改 iss.C 对应部分：
void iss::Loop()
{
TFile *f = new TFile("iss.root","RECREATE");
TH1F *h = new TH1F("h","hist of pro",20., 0., 20.);
if (fChain == 0) return;
Long64_t nentries = fChain->GetEntriesFast();
Long64_t nbytes = 0, nb = 0;
for (Long64_t jentry=0; jentry<nentries;jentry++) {
Long64_t ientry = LoadTree(jentry);
if (ientry < 0) break;
nb = fChain->GetEntry(jentry); nbytes += nb;
if (Cut(ientry) < 0) continue;
h->Fill(nrichhit);
}
h->Write();
f->Write();
f->Close();
}
生成ROOT文件：
(ams) zpw@dell:~/Files/0520_iss$ root iss.C+
------------------------------------------------------------------
| Welcome to ROOT 6.26/10 https://root.cern |
| (c) 1995-2021, The ROOT Team; conception: R. Brun, F. Rademakers |
| Built for linuxx8664gcc on Nov 17 2022, 16:18:00 |
| From tag , 16 November 2022 |
| With |
| Try '.help', '.demo', '.license', '.credits', '.quit'/'.q' |
------------------------------------------------------------------
root [0]
Processing iss.C+...
Info in <TUnixSystem::ACLiC>: creating shared library /home/zpw/Files/0520_iss/./iss_C.so
(iss) @0x55cb437a41b0
root [1] iss hello
(iss &) @0x7fd492fff000
root [2] hello.Loop()
root [3]
写个画图脚本Macros: plot.C
void plot()
{
// open file
TFile *input=new TFile("./iss.root");
input->ls();
auto *c1=new TCanvas();
// Get histogram
TH1F *hist=static_cast<TH1F*>(input->Get("h"));
// setting/style
gPad->SetLogy();
gStyle->SetOptStat(0);
// hist->SetMinimum(1e-5);
// hist->SetMaximum(1.0);
hist->Scale(1.0/hist->Integral());
hist->GetYaxis()->SetRangeUser(1e-5,1.0);
hist->SetLineColor(kBlue-4);
// hist->SetMarkerColor(kBlue-4);
// hist->SetMarkerStyle(2);
// draw
// hist->Draw("HIST P");
hist->Draw("HIST");
TLegend *leg_line = new TLegend(0.7, 0.8, 0.85, 0.72);
leg_line->SetTextFont(3);
leg_line->SetTextSize(25);
leg_line->SetFillColor(0);
leg_line->SetLineColor(1);
leg_line->AddEntry(hist, "proton", "p");
leg_line->Draw("SAME");
c1->Print("./pro.png");
}
画出来root -q plot.C：
**
标签：return,iss,root,TFile,画图,hist,空间站,line,数据 From： https://www.cnblogs.com/zhaopw5/p/17417703.html