splitting csvs in python

split_csvs.py

import csv
import os

source_filename = 'all.csv'

records_per_file = 1000
target_file_prefix = 'target/split'

with open(source_filename, 'r') as source:
    reader = csv.reader(source)
    headers = next(reader)

    file_idx = 0
    records_exist = True

    while records_exist:

        i = 0
        target_filename = f'{target_file_prefix}_{file_idx}.csv'

        with open(target_filename, 'w') as target:
            writer = csv.writer(target)

            while i < records_per_file:
                if i == 0:
                    writer.writerow(headers)

                try:
                    writer.writerow(next(reader))
                    i += 1
                except:
                    records_exist = False
                    break

        if i == 0:
            # we only wrote the header, so delete that file
            os.remove(target_filename)

        file_idx += 1