%%cpp -d
#include "RooRealVar.h"
#include "RooDataSet.h"
#include "RooDataHist.h"
#include "RooGaussian.h"
#include "RooPolyVar.h"
#include "RooProdPdf.h"
#include "RooPlot.h"
#include "TRandom.h"
#include "TCanvas.h"
#include "TAxis.h"
#include "TH1.h"

using namespace RooFit;

RooDataSet *makeFakeDataXY();

%%cpp -d
RooDataSet *makeFakeDataXY()
{
   RooRealVar x("x", "x", -10, 10);
   RooRealVar y("y", "y", -10, 10);
   RooArgSet coord(x, y);

   RooDataSet *d = new RooDataSet("d", "d", RooArgSet(x, y));

   for (int i = 0; i < 10000; i++) {
      double tmpy = gRandom->Gaus(0, 10);
      double tmpx = gRandom->Gaus(0.5 * tmpy, 1);
      if (fabs(tmpy) < 10 && fabs(tmpx) < 10) {
         x.setVal(tmpx);
         y.setVal(tmpy);
         d->add(coord);
      }
   }

   return d;
}

RooRealVar x("x", "x", -10, 10);
RooRealVar y("y", "y", -10, 10);

RooRealVar a0("a0", "a0", -0.5, -5, 5);
RooRealVar a1("a1", "a1", -0.5, -1, 1);
RooPolyVar fy("fy", "fy", y, RooArgSet(a0, a1));

RooRealVar sigma("sigma", "width of gaussian", 0.5, 0.1, 2.0);
RooGaussian model("model", "Gaussian with shifting mean", x, fy, sigma);

RooDataSet *expDataXY = makeFakeDataXY();

std::unique_ptr<RooAbsData> expAbsDataY{expDataXY->reduce(y)};
RooDataSet *expDataY = static_cast<RooDataSet*>(expAbsDataY.get());

std::unique_ptr<RooDataSet> data{model.generate(x, ProtoData(*expDataY))};
data->Print();

model.fitTo(*expDataXY, ConditionalObservables(y), PrintLevel(-1));

RooPlot *xframe = x.frame();
expDataXY->plotOn(xframe);
model.plotOn(xframe, ProjWData(*expDataY));

std::unique_ptr<RooDataHist> binnedDataY{expDataY->binnedClone()};
model.plotOn(xframe, ProjWData(*binnedDataY), LineColor(kCyan), LineStyle(kDotted));

((RooRealVar *)expDataY->get()->find("y"))->setBins(5);
std::unique_ptr<RooDataHist> binnedDataY2{expDataY->binnedClone()};
model.plotOn(xframe, ProjWData(*binnedDataY2), LineColor(kRed));

new TCanvas("rf303_conditional", "rf303_conditional", 600, 460);
gPad->SetLeftMargin(0.15);
xframe->GetYaxis()->SetTitleOffset(1.2);
xframe->Draw();

%jsroot on
gROOT->GetListOfCanvases()->Draw()