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approx.C
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1/// \file
2/// \ingroup tutorial_graphs
3/// \notebook -js
4/// Macro to test interpolation function Approx
5///
6/// \macro_image
7/// \macro_code
8///
9/// \author Christian Stratowa, Vienna, Austria.
10
11TCanvas *vC1;
12TGraph *grxy, *grin, *grout;
13
14void DrawSmooth(Int_t pad, const char *title, const char *xt, const char *yt)
15{
16 vC1->cd(pad);
17 TH1F *vFrame = gPad->DrawFrame(0,0,15,150);
18 vFrame->SetTitle(title);
19 vFrame->SetTitleSize(0.2);
20 vFrame->SetXTitle(xt);
21 vFrame->SetYTitle(yt);
22 grxy->SetMarkerColor(kBlue);
23 grxy->SetMarkerStyle(21);
24 grxy->SetMarkerSize(0.5);
25 grxy->Draw("P");
26 grin->SetMarkerColor(kRed);
27 grin->SetMarkerStyle(5);
28 grin->SetMarkerSize(0.7);
29 grin->Draw("P");
30 grout->DrawClone("LP");
31}
32
33void approx()
34{
35// Test data (square)
36 Int_t n = 11;
37 Double_t x[] = {1,2,3,4,5,6,6,6,8,9,10};
38 Double_t y[] = {1,4,9,16,25,25,36,49,64,81,100};
39 grxy = new TGraph(n,x,y);
40
41// X values, for which y values should be interpolated
42 Int_t nout = 14;
43 Double_t xout[] =
44 {1.2,1.7,2.5,3.2,4.4,5.2,5.7,6.5,7.6,8.3,9.7,10.4,11.3,13};
45
46// Create Canvas
47 vC1 = new TCanvas("vC1","square",200,10,700,700);
48 vC1->Divide(2,2);
49
50// Initialize graph with data
51 grin = new TGraph(n,x,y);
52// Interpolate at equidistant points (use mean for tied x-values)
53 TGraphSmooth *gs = new TGraphSmooth("normal");
54 grout = gs->Approx(grin,"linear");
55 DrawSmooth(1,"Approx: ties = mean","X-axis","Y-axis");
56
57// Re-initialize graph with data
58// (since graph points were set to unique vales)
59 grin = new TGraph(n,x,y);
60// Interpolate at given points xout
61 grout = gs->Approx(grin,"linear", 14, xout, 0, 130);
62 DrawSmooth(2,"Approx: ties = mean","","");
63
64// Print output variables for given values xout
65 Int_t vNout = grout->GetN();
66 Double_t vXout, vYout;
67 for (Int_t k=0;k<vNout;k++) {
68 grout->GetPoint(k, vXout, vYout);
69 cout << "k= " << k << " vXout[k]= " << vXout
70 << " vYout[k]= " << vYout << endl;
71 }
72
73// Re-initialize graph with data
74 grin = new TGraph(n,x,y);
75// Interpolate at equidistant points (use min for tied x-values)
76// _grout = gs->Approx(grin,"linear", 50, 0, 0, 0, 1, 0, "min");_
77 grout = gs->Approx(grin,"constant", 50, 0, 0, 0, 1, 0.5, "min");
78 DrawSmooth(3,"Approx: ties = min","","");
79
80// Re-initialize graph with data
81 grin = new TGraph(n,x,y);
82// Interpolate at equidistant points (use max for tied x-values)
83 grout = gs->Approx(grin,"linear", 14, xout, 0, 0, 2, 0, "max");
84 DrawSmooth(4,"Approx: ties = max","","");
85
86// Cleanup
87 delete gs;
88}
89
int Int_t
Definition: RtypesCore.h:45
double Double_t
Definition: RtypesCore.h:59
@ kRed
Definition: Rtypes.h:66
@ kBlue
Definition: Rtypes.h:66
#define gPad
Definition: TVirtualPad.h:288
virtual void SetMarkerColor(Color_t mcolor=1)
Set the marker color.
Definition: TAttMarker.h:38
virtual void SetMarkerStyle(Style_t mstyle=1)
Set the marker style.
Definition: TAttMarker.h:40
virtual void SetMarkerSize(Size_t msize=1)
Set the marker size.
Definition: TAttMarker.h:45
The Canvas class.
Definition: TCanvas.h:23
TVirtualPad * cd(Int_t subpadnumber=0) override
Set current canvas & pad.
Definition: TCanvas.cxx:711
A helper class to smooth TGraph.
Definition: TGraphSmooth.h:36
TGraph * Approx(TGraph *grin, Option_t *option="linear", Int_t nout=50, Double_t *xout=nullptr, Double_t yleft=0, Double_t yright=0, Int_t rule=0, Double_t f=0, Option_t *ties="mean")
Approximate data points.
A TGraph is an object made of two arrays X and Y with npoints each.
Definition: TGraph.h:41
Int_t GetN() const
Definition: TGraph.h:126
void Draw(Option_t *chopt="") override
Draw this graph with its current attributes.
Definition: TGraph.cxx:808
virtual Int_t GetPoint(Int_t i, Double_t &x, Double_t &y) const
Get x and y values for point number i.
Definition: TGraph.cxx:1520
1-D histogram with a float per channel (see TH1 documentation)}
Definition: TH1.h:577
virtual void SetTitleSize(Float_t size=0.02, Option_t *axis="X")
Set the axis' title size.
Definition: Haxis.cxx:365
void SetTitle(const char *title) override
Change (i.e.
Definition: TH1.cxx:6700
virtual void SetXTitle(const char *title)
Definition: TH1.h:415
virtual void SetYTitle(const char *title)
Definition: TH1.h:416
virtual TObject * DrawClone(Option_t *option="") const
Draw a clone of this object in the current selected pad for instance with: gROOT->SetSelectedPad(gPad...
Definition: TObject.cxx:298
void Divide(Int_t nx=1, Int_t ny=1, Float_t xmargin=0.01, Float_t ymargin=0.01, Int_t color=0) override
Automatic pad generation by division.
Definition: TPad.cxx:1153
Double_t y[n]
Definition: legend1.C:17
Double_t x[n]
Definition: legend1.C:17
const Int_t n
Definition: legend1.C:16