Python Function to Split CSV File with headers

csv_split.py

# coding: utf-8
import csv
import os

from itertools import tee, islice


LINES_SPLIT = 1000

def chunks(l, n):
    """
    Source: https://stackoverflow.com/a/22045226/2369204
    """
    it = iter(l)
    return iter(lambda: tuple(islice(it, n)), ())

directory = "output"

if not os.path.exists(directory):
    os.makedirs(directory)
    print("created directory")

files = list(filter(lambda f : f.endswith('csv'), os.listdir(".")))

for file in files:
    with open(files[0],'r') as infile:
        reader = csv.DictReader(infile)
        for counter, rows in enumerate(chunks(reader, LINES_SPLIT), start=1):
            headers = rows[0].keys()
            print("splitting part {} of {}".format(counter,file))
            with open("output/{}_split_{}.{}".format(file.split(".")[0], counter, file.split(".")[1]), mode='w') as out_file:
                dict_writer = csv.DictWriter(out_file, headers, quotechar='\"',quoting=csv.QUOTE_ALL, lineterminator="\r\n")
                dict_writer.writeheader()
                dict_writer.writerows(rows)