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

# # df006_ranges
# Use Range to limit the amount of data processed.
# 
# This tutorial shows how to express the concept of ranges when working with the RDataFrame.
# 
# 
# 
# 
# **Author:** Danilo Piparo (CERN)  
# <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 11:07 AM.</small></i>

# In[1]:


import ROOT

def fill_tree(treeName, fileName):
    df = ROOT.RDataFrame(100)
    df.Define("b1", "(int) rdfentry_")\
      .Define("b2", "(float) rdfentry_ * rdfentry_").Snapshot(treeName, fileName)


# We prepare an input tree to run on

# In[2]:


fileName = "df006_ranges_py.root"
treeName = "myTree"

fill_tree(treeName, fileName)


# We read the tree from the file and create a RDataFrame.

# In[3]:


d = ROOT.RDataFrame(treeName, fileName)


# ## Usage of ranges
# Now we'll count some entries using ranges

# In[4]:


c_all = d.Count()


# This is how you can express a range of the first 30 entries

# In[5]:


d_0_30 = d.Range(30) 
c_0_30 = d_0_30.Count()


# This is how you pick all entries from 15 onwards

# In[6]:


d_15_end = d.Range(15, 0)
c_15_end = d_15_end.Count()


# We can use a stride too, in this case we pick an event every 3 entries

# In[7]:


d_15_end_3 = d.Range(15, 0, 3)
c_15_end_3 = d_15_end_3.Count()


# The Range here acts first on the (whole) RDataFrame graph:
# Not only actions (like Count) but also filters and new columns can be added to it.

# In[8]:


d_0_50 = d.Range(50)
c_0_50_odd_b1 = d_0_50.Filter("1 == b1 % 2").Count()


# An important thing to notice is that the counts of a filter are relative to the
# number of entries a filter "sees". Therefore, if a Range depends on a filter,
# the Range will act on the entries passing the filter only.

# In[9]:


c_0_3_after_even_b1 = d.Filter("0 == b1 % 2").Range(0, 3).Count()


# Ok, time to wrap up: let's print all counts!

# In[10]:


print("Usage of ranges:")
print(" - All entries:", c_all.GetValue())
print(" - Entries from 0 to 30:", c_0_30.GetValue())
print(" - Entries from 15 onwards:", c_15_end.GetValue())
print(" - Entries from 15 onwards in steps of 3:", c_15_end_3.GetValue())
print(" - Entries from 0 to 50, odd only:", c_0_50_odd_b1.GetValue())
print(" - First three entries of all even entries:", c_0_3_after_even_b1.GetValue())