doc/master/rf104__classfactory_8py.html

import ROOT


# Write class skeleton code

# --------------------------------------------------


# Write skeleton pdf class with variable x,a,b

# To use this class,

#    - Edit the file MyPdfV1.cxx and implement the evaluate() method in terms of x,a and b

#    - Compile and link class with '.x MyPdfV1.cxx+'

#

ROOT.RooClassFactory.makePdf("MyPdfV1", "x,A,B")


# With added initial value expression

# ---------------------------------------------------------------------


# Write skeleton pdf class with variable x,a,b and given formula expression

# To use this class,

#    - Compile and link class with '.x MyPdfV2.cxx+'

#

ROOT.RooClassFactory.makePdf("MyPdfV2", "x,A,B", "", "A*fabs(x)+pow(x-B,2)")


# With added analytical integral expression

# ---------------------------------------------------------------------------------


# Write skeleton pdf class with variable x,a,b, given formula expression _and_

# given expression for analytical integral over x

# To use this class,

#    - Compile and link class with '.x MyPdfV3.cxx+'

#

ROOT.RooClassFactory.makePdf(

    "MyPdfV3",

    "x,A,B",

    "",

    "A*fabs(x)+pow(x-B,2)",

    True,

    False,

    "x:(A/2)*(pow(x.max(rangeName),2)+pow(x.min(rangeName),2))+(1./3)*(pow(x.max(rangeName)-B,3)-pow(x.min(rangeName)-B,3))",

)


# Use instance of created class

# ---------------------------------------------------------


# Compile MyPdfV3 class

ROOT.gROOT.ProcessLineSync(".x MyPdfV3.cxx+")


# Creat instance of MyPdfV3 class

a = ROOT.RooRealVar("a", "a", 1)

b = ROOT.RooRealVar("b", "b", 2, -10, 10)

y = ROOT.RooRealVar("y", "y", -10, 10)

pdf = ROOT.MyPdfV3("pdf", "pdf", y, a, b)


# Generate toy data from pdf and plot data and pdf on frame

frame1 = y.frame(Title="Compiled class MyPdfV3")

data = pdf.generate({y}, 1000)

pdf.fitTo(data, PrintLevel=-1)

data.plotOn(frame1)

pdf.plotOn(frame1)


# /

# C o m p i l e d   v e r s i o n   o f   e x a m p l e   r f 1 0 3 #

# /


# Declare observable x

x = ROOT.RooRealVar("x", "x", -20, 20)


# The ROOT.RooClassFactory.makePdfInstance() function performs code writing, compiling, linking

# and object instantiation in one go and can serve as a straight

# replacement of ROOT.RooGenericPdf


alpha = ROOT.RooRealVar("alpha", "alpha", 5, 0.1, 10)

genpdf = ROOT.RooClassFactory.makePdfInstance("GenPdf", "(1+0.1*fabs(x)+sin(sqrt(fabs(x*alpha+0.1))))", [x, alpha])


# Generate a toy dataset from the interpreted pdf

data2 = genpdf.generate({x}, 50000)


# Fit the interpreted pdf to the generated data

genpdf.fitTo(data2, PrintLevel=-1)


# Make a plot of the data and the pdf overlaid

frame2 = x.frame(Title="Compiled version of pdf of rf103")

data2.plotOn(frame2)

genpdf.plotOn(frame2)


# Draw all frames on a canvas

c = ROOT.TCanvas("rf104_classfactory", "rf104_classfactory", 800, 400)

c.Divide(2)

c.cd(1)

ROOT.gPad.SetLeftMargin(0.15)

frame1.GetYaxis().SetTitleOffset(1.4)

frame1.Draw()

c.cd(2)

ROOT.gPad.SetLeftMargin(0.15)

frame2.GetYaxis().SetTitleOffset(1.4)

frame2.Draw()


c.SaveAs("rf104_classfactory.png")