portable way to write csv file in python 2 or python 3

Question

On my Windows box, I usually did this in python 2 to write a csv file:

import csv
f = open(\"out.csv\",\"wb\")
cr = csv.writer(f,delimiter=\';\')
cr.writerow         


        

Answer 1

For both reading and writing csv files, I've found no better way either — however I would encapsulate into a separate function as shown below. The advantage being that the logic is all in one place instead of duplicated if it's needed more than once.

import csv
import sys

def open_csv(filename, mode='r'):
    """Open a csv file in proper mode depending on Python verion."""
    return(open(filename, mode=mode+'b') if sys.version_info[0] == 2 else
           open(filename, mode=mode, newline=''))

with open_csv('out.csv', 'w') as f:
    writer = csv.writer(f, delimiter=';')
    writer.writerow([1, 2, 3])
    writer.writerow(['a', 'b', 'c'])

Answer 2

On Windows, I found a python 2 & 3 compliant way of doing it changing csv lineterminator option (which defaults to "\r\n" which makes one \r too many when file is open in text mode in Windows)

import csv

with open("out.csv","w") as f:
    cr = csv.writer(f,delimiter=";",lineterminator="\n")
    cr.writerow(["a","b","c"])
    cr.writerow(["d","e","f"])
    cr.writerow(["a","b","c"])
    cr.writerow(["d","e","f"])

Whatever the python version, that will create a csv file without the infamous "blank lines".

The only drawback is that on Linux, this method would produce \r-free files, which is maybe not the standard (although files still opens properly in excel, no blank lines and still several lines :))

the problem persists on 3.6.2 (Just checked myself like I should have some time ago)