append my results to a file

[clarablanes]

good morning guys,

I need help:

I have done a program to obtain some data and then I have to append this data to the original file. My original file is something like this (with hundred more lines):

Verapamil,sub,COC1=C(OC)C=C(CCN©CCCC(C#N)(C©C)C2=CC(OC)=C(OC)C=C2)C=C1
Norverapamil,sub,COC1=CC=C(CCNCCCC(C#N)(C©C)C2=CC(OC)=C(OC)C=C2)C=C1OC
levofloxacin,sub,C[C@H]1COC2=C3N1C=C(C(O)=O)C(=O)C3=CC(F)=C2N1CCN©CC1
.
.
.

I need to take each third entry (in bold), process it to obtain a data and append this value to the original file, separated by comma.
I show you my program below. I am able to obtain the values and I see them on the screen but I don't find the way to append them to the original file. Could you help me with this, please?

import os
import subprocess
path_input = '/home/c.blanes/pgp/training.txt'
obabel = '/usr/bin/obabel '
 
f = open(path_input, 'r')

for line in f.readlines():

	smiles = line.split(',')[2].strip('\n')
	print(smiles)
	
	launch = obabel + '-:\'%s\' -otxt --append TPSA'%(smiles)
	print (launch)
	subprocess.call(launch, shell=True)