void approx()
{
//**********************************************
// Macro to test interpolation function Approx
// Author: Christian Stratowa, Vienna, Austria.
// Created: 26 Aug 2001
//**********************************************
// test data (square)
Int_t n = 11;
Double_t x[] = {1,2,3,4,5,6,6,6,8,9,10};
Double_t y[] = {1,4,9,16,25,25,36,49,64,81,100};
grxy = new TGraph(n,x,y);
// x values, for which y values should be interpolated
Int_t nout = 14;
Double_t xout[] =
{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};
// create Canvas
vC1 = new TCanvas("vC1","square",200,10,700,700);
vC1->Divide(2,2);
// initialize graph with data
grin = new TGraph(n,x,y);
// interpolate at equidistant points (use mean for tied x-values)
TGraphSmooth *gs = new TGraphSmooth("normal");
grout = gs->Approx(grin,"linear");
DrawSmooth(1,"Approx: ties = mean","X-axis","Y-axis");
// re-initialize graph with data
// (since graph points were set to unique vales)
grin = new TGraph(n,x,y);
// interpolate at given points xout
grout = gs->Approx(grin,"linear", 14, xout, 0, 130);
DrawSmooth(2,"Approx: ties = mean","","");
// print output variables for given values xout
Int_t vNout = grout->GetN();
Double_t vXout, vYout;
for (Int_t k=0;k<vNout;k++) {
grout->GetPoint(k, vXout, vYout);
cout << "k= " << k << " vXout[k]= " << vXout
<< " vYout[k]= " << vYout << endl;
}
// re-initialize graph with data
grin = new TGraph(n,x,y);
// interpolate at equidistant points (use min for tied x-values)
// grout = gs->Approx(grin,"linear", 50, 0, 0, 0, 1, 0, "min");
grout = gs->Approx(grin,"constant", 50, 0, 0, 0, 1, 0.5, "min");
DrawSmooth(3,"Approx: ties = min","","");
// re-initialize graph with data
grin = new TGraph(n,x,y);
// interpolate at equidistant points (use max for tied x-values)
grout = gs->Approx(grin,"linear", 14, xout, 0, 0, 2, 0, "max");
DrawSmooth(4,"Approx: ties = max","","");
// cleanup
delete gs;
}
void motorcycle()
{
// data taken from R library MASS: mcycle.txt
TString dir = gROOT->GetTutorialDir();
dir.Append("/graphs/");
dir.ReplaceAll("/./","/");
// read file and add to fit object
Double_t *x = new Double_t[133];
Double_t *y = new Double_t[133];
Double_t vX, vY;
Int_t vNData = 0;
ifstream vInput;
vInput.open(Form("%smotorcycle.dat",dir.Data()));
while (1) {
vInput >> vX >> vY;
if (!vInput.good()) break;
x[vNData] = vX;
y[vNData] = vY;
vNData++;
}//while
vInput.close();
grin = new TGraph(vNData,x,y);
// draw graph
vC1 = new TCanvas("vC1","Smooth Regression",200,10,900,700);
vC1->Divide(2,3);
// Kernel Smoother
// create new kernel smoother and smooth data with bandwidth = 2.0
TGraphSmooth *gs = new TGraphSmooth("normal");
grout = gs->SmoothKern(grin,"normal",2.0);
DrawSmooth(1,"Kernel Smoother: bandwidth = 2.0","times","accel");
// redraw ksmooth with bandwidth = 5.0
grout = gs->SmoothKern(grin,"normal",5.0);
DrawSmooth(2,"Kernel Smoother: bandwidth = 5.0","","");
// Lowess Smoother
// create new lowess smoother and smooth data with fraction f = 2/3
grout = gs->SmoothLowess(grin,"",0.67);
DrawSmooth(3,"Lowess: f = 2/3","","");
// redraw lowess with fraction f = 0.2
grout = gs->SmoothLowess(grin,"",0.2);
DrawSmooth(4,"Lowess: f = 0.2","","");
// Super Smoother
// create new super smoother and smooth data with default bass = 0 and span = 0
grout = gs->SmoothSuper(grin,"",0,0);
DrawSmooth(5,"Super Smoother: bass = 0","","");
// redraw supsmu with bass = 3 (smoother curve)
grout = gs->SmoothSuper(grin,"",3);
DrawSmooth(6,"Super Smoother: bass = 3","","");
// cleanup
delete [] x;
delete [] y;
delete gs;
}
