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

# # df008_createDataSetFromScratch
# Create data from scratch with RDataFrame.
# 
# This tutorial shows how to create a dataset from scratch with 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


# We create an empty data frame of 100 entries

# In[2]:


df = ROOT.RDataFrame(100)


# We now fill it with random numbers

# In[3]:


ROOT.gRandom.SetSeed(1)
df_1 = df.Define("rnd", "gRandom->Gaus()")


# And we write out the dataset on disk

# In[4]:


df_1.Snapshot("randomNumbers", "df008_createDataSetFromScratch_py.root")