按名称寻找 TF1
TF1 *ffitold = (TF1*)gROOT->GetListOfFunctions()->FindObject(FunName);
直接将自定义的类写入 tree
fitdata *fd = new fitdata(0, 4000); TTree *tr = new TTree("tree","waveform fit analysis"); tr->Branch("fd", &fd, 64000, 1);
g++ 编译同时出图
1 int main(int argc, char *argv[]) 2 { 3 TApplication the_app("app", &argc, argv); 4 ... 5 the_app.Run(); 6 return 0; 7 }
设置字体
颜色和标志的编号
root 中的数据长度
TString 初始化
1 TString m("foobarbaz"); 2 TString option="IESN"; 3 TString file = dir+“/spectrum/TSpectrum.root”; //dir是TString类型
TString Format()
1 TString filename = Form("%s.root", jobname); 2 TString workarea = Form("%s/proof", tutdir.Data()); 3 cmd = Form("kill -9 %d", pid);
写一个简单的 tree
- branch 为普通变量
1 TTree t1("t1","a simple Tree with simple variables"); 2 Double_t random; 3 t1.Branch("random",&random,"random/D"); 4 random = gRandom->Rndm(); 5 t1.Fill();
- branch 为固定长度数组，注意这里的 10 需要是的数字，而不是某个 const 的值
1 Float_t f[10]; 2 tree->Branch("fBranch",f,"f[10]/F");
- branch 为可变长度数组，可以设置最大长度
1 Int_t nPhot; 2 Float_t E[500]; 3 TTree* nEmcPhotons = new TTree("nEmcPhotons","EMC Photons"); 4 nEmcPhotons->Branch("nPhot",&nPhot,"nPhot/I"); 5 nEmcPhotons->Branch("E",E,"E[nPhot]/F");
tree 的数据简写
读一个 tree
1 TTree* htx = (TTree*)fin->Get("htx"); 2 3 Int_t nevt; 4 Double_t datay[size]; 5 Double_t dty[size]; 6 htx->SetBranchAddress("nevt", &nevt); 7 htx->SetBranchAddress("datay", datay); 8 htx->SetBranchAddress("dty", dty);
tree Draw 方法
1 t->Draw(“data:dt”, “nevt == 0”, “L”)； 2 3 tree.Draw("sqrt(x)>>hsqrt","y>0") 4 TH1F *hsqrt = (TH1F*)gDirectory->Get("hsqrt");
TRandom 类
1 TH1D* h1 = new TH1D("h1", "", 200, 0, 200); 2 for(Int_t i = 0; i < 100000; i++){ 3 h1->Fill(gRandom->Gaus(100, 10)); 4 h1->Fill(200*gRandom->Rndm(1)); 5 } 6 7 h1->Draw();
TFile Close 函数
Tfile 类对象可以用 cd() 方法进入，需要用 Close() 方法关闭，如果在这之前有根据 file 里的内容做出的图像，会随着 Close() 方法而失效。 这种情况不会报错。如果 delete 了对象，并试图调用，则会报错。
TFit 中为拟合参数设置范围限制
1 TF1 *ffit = new TF1(FunName,langaufun,fitrange[0],fitrange[1],4); 2 ffit->SetParameters(startvalues); 3 ffit->SetParNames("Width","MP","Area","GSigma"); 4 5 for (i=0; i<4; i++) { 6 ffit->SetParLimits(i, parlimitslo[i], parlimitshi[i]); 7 } 8 9 his->Fit(FunName,"RB0"); // fit within specified range, use ParLimits, do not plot
TLegend 类
1 TLgend *len = new TLgend(0.7, 0.65, 0.86, 0.88); 2 len->AddEntry(h1, "24#mus", "l"); 3 len->AddEntry(h2, "26#mus", "l"); 4 len->AddEntry(h3, "28#mus", "l"); 5 len->Draw();
TLatex 类
1 TLatex *text = new TLatex(0.2, 200, Form("#tau_{p}=\d#mus", taup)); 2 text->SetTextFont(22); 3 text->SetTextSize(0.06); 4 text->Draw()
