Append text in existing file in Python - Day 11

appendlines.py

from numpy import*

values = []

#after operations using values array, we write the output to a text file

with open("appendLines.txt", "a") as newf:
	newf.write('\n')
	newf.write(str(len(values)))
	newf.write('\t')
	newf.write(str(sum(values)))
	newf.write('\t')
	newf.write(str(average(values)))
	#newf.write('\n')
newf.close

When you open with "a" mode , the write position will always be at the end of the file (an append). There are other permutations of the mode argument for updating (+), truncating (w) and binary (b) mode but starting with just "a" is your best. If you want to seek through the file to find the place where you should insert the line, use 'r+'.

The following code append a text in the existing file:

with open("index.txt", "a") as myfile:
    myfile.write("text appended")

source: How to append a file in Python