#!/usr/bin/env python
# coding: utf-8

# # rf706_histpdf
# Special pdf's: histogram based pdfs and functions
# 
# 
# 
# 
# **Author:**  Clemens Lange, Wouter Verkerke (C++ version)  
# <i><small>This notebook tutorial was automatically generated with <a href= "https://github.com/root-project/root/blob/master/documentation/doxygen/converttonotebook.py">ROOTBOOK-izer</a> from the macro found in the ROOT repository  on Wednesday, April 17, 2024 at 11:19 AM.</small></i>

# In[1]:


import ROOT


# Create pdf for sampling
# ---------------------------------------------

# In[2]:


x = ROOT.RooRealVar("x", "x", 0, 20)
p = ROOT.RooPolynomial("p", "p", x, [0.01, -0.01, 0.0004])


# Create low stats histogram
# ---------------------------------------------------

# Sample 500 events from p

# In[3]:


x.setBins(20)
data1 = p.generate({x}, 500)


# Create a binned dataset with 20 bins and 500 events

# In[4]:


hist1 = data1.binnedClone()


# Represent data in dh as pdf in x

# In[5]:


histpdf1 = ROOT.RooHistPdf("histpdf1", "histpdf1", {x}, hist1, 0)


# Plot unbinned data and histogram pdf overlaid

# In[6]:


frame1 = x.frame(Title="Low statistics histogram pdf", Bins=100)
data1.plotOn(frame1)
histpdf1.plotOn(frame1)


# Create high stats histogram
# -----------------------------------------------------

# Sample 100000 events from p

# In[7]:


x.setBins(10)
data2 = p.generate({x}, 100000)


# Create a binned dataset with 10 bins and 100K events

# In[8]:


hist2 = data2.binnedClone()


# Represent data in dh as pdf in x, 2nd order interpolation

# In[9]:


histpdf2 = ROOT.RooHistPdf("histpdf2", "histpdf2", {x}, hist2, 2)


# Plot unbinned data and histogram pdf overlaid

# In[10]:


frame2 = x.frame(Title="High stats histogram pdf with interpolation", Bins=100)
data2.plotOn(frame2)
histpdf2.plotOn(frame2)

c = ROOT.TCanvas("rf706_histpdf", "rf706_histpdf", 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(1.8)
frame2.Draw()

c.SaveAs("rf706_histpdf.png")


# Draw all canvases 

# In[11]:


from ROOT import gROOT 
gROOT.GetListOfCanvases().Draw()