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

# # vo004_SortAndSelect
# In this tutorial we learn how elements of an RVec can be easily sorted and
# selected.
# 
# 
# 
# 
# **Author:** Stefan Wunsch  
# <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 11:24 AM.</small></i>

# In[1]:


import ROOT
from ROOT.VecOps import Argsort, Take, Sort, Reverse


# RVec can be sorted in Python with the inbuilt sorting function because
# PyROOT implements a Python iterator

# In[2]:


v1 = ROOT.RVecD(3)
v1[0], v1[1], v1[2] = 6, 4, 5
v2 = sorted(v1)
print("Sort vector {}: {}".format(v1, v2))


# For convenience, ROOT implements helpers, e.g., to get a sorted copy of
# an RVec ...

# In[3]:


v2 = Sort(v1);
print("Sort vector {}: {}".format(v1, v2))


# ... or a reversed copy of an RVec.

# In[4]:


v2 = Reverse(v1);
print("Reverse vector {}: {}".format(v1, v2))


# Helpers are provided to get the indices that sort the vector and to
# select these indices from an RVec.

# In[5]:


v2 = Argsort(v1)
print("Indices that sort the vector {}: {}".format(v1, v2))

v3 = ROOT.RVecD(3)
v3[0], v3[1], v3[2] = 9, 7, 8
v4 = Take(v3, v2)
print("Sort vector {} respective to the previously determined indices: {}".format(v3, v4))


# Take can also be used to get the first or last elements of an RVec.

# In[6]:


v2 = Take(v1, 2)
v3 = Take(v1, -2)
print("Take the two first and last elements of vector {}: {}, {}".format(v1, v2, v3))


# Because the VecOps helpers return a copy of the input, you can chain the operations
# conveniently.

# In[7]:


v2 = Reverse(Take(Sort(v1), -2))
print("Sort the vector {}, take the two last elements and reverse the selection: {}".format(v1, v2))