Writing a list to a file with Python

Question

Is this the cleanest way to write a list to a file, since writelines() doesn\'t insert newline characters?

file.writelines([\"%s\\n\" % item  fo         


        

Answer 1

file.write('\n'.join(list))

Answer 2

Why don't you try

file.write(str(list))

Answer 3

poem = '''\
Programming is fun
When the work is done
if you wanna make your work also fun:
use Python!
'''
f = open('poem.txt', 'w') # open for 'w'riting
f.write(poem) # write text to file
f.close() # close the file

How It Works: First, open a file by using the built-in open function and specifying the name of the file and the mode in which we want to open the file. The mode can be a read mode (’r’), write mode (’w’) or append mode (’a’). We can also specify whether we are reading, writing, or appending in text mode (’t’) or binary mode (’b’). There are actually many more modes available and help(open) will give you more details about them. By default, open() considers the file to be a ’t’ext file and opens it in ’r’ead mode. In our example, we first open the file in write text mode and use the write method of the file object to write to the file and then we finally close the file.

The above example is from the book "A Byte of Python" by Swaroop C H. swaroopch.com

Answer 4

Using Python 3 and Python 2.6+ syntax:

with open(filepath, 'w') as file_handler:
    for item in the_list:
        file_handler.write("{}\n".format(item))

This is platform-independent. It also terminates the final line with a newline character, which is a UNIX best practice.

Starting with Python 3.6, "{}\n".format(item) can be replaced with an f-string: f"{item}\n".

Answer 5

This logic will first convert the items in list to string(str). Sometimes the list contains a tuple like

alist = [(i12,tiger), 
(113,lion)]

This logic will write to file each tuple in a new line. We can later use eval while loading each tuple when reading the file:

outfile = open('outfile.txt', 'w') # open a file in write mode
for item in list_to_persistence:    # iterate over the list items
   outfile.write(str(item) + '\n') # write to the file
outfile.close()   # close the file 

Answer 6

In General

Following is the syntax for writelines() method

fileObject.writelines( sequence )

Example

#!/usr/bin/python

# Open a file
fo = open("foo.txt", "rw+")
seq = ["This is 6th line\n", "This is 7th line"]

# Write sequence of lines at the end of the file.
line = fo.writelines( seq )

# Close opend file
fo.close()

Reference

http://www.tutorialspoint.com/python/file_writelines.htm