Как из текстового файла БЫСТРО создать заданное количество файлов с заданным количеством строк Python?

москва|1000
санкт-петербург|1100

__author__ = 'kascode'
from random import randint
import os

source = open('names.txt', 'r')

sourcelines = source.readlines()
sourcelineslen = len(sourcelines)

def readCities():
    with open('cities.txt', 'r') as f:
        citylines = f.readlines()

    citieslist = []
    
    # заполняем список данными в формате [['город'], ['число строк']] 
    for line in citylines:
        citieslist.append(line.split('|'))

    return citieslist

for city in readCities():
    # создаём папку с именем города
    if not os.path.exists(city[0]):
        os.makedirs(city[0])

    file = city[0] + '/name.txt'
    cityout = open(file, 'w')
    written = []        # массив записанных строк

    # записываем столько строк, сколько указано для города
    for i in range(1, int(city[1])):
        # берём случайную строку из исходного списка
        sourceline = sourcelines[randint(0, sourcelineslen-1)]
        
        # берём новую пока не найдём не дублирующую
        while sourceline in written:
            sourceline = sourcelines[randint(0, sourcelineslen-1)]

        cityout.write(sourceline)
        written.append(sourceline)

#! /usr/bin/env python
# File:          rndappend.py
#
# Created:       Sat 20 Dec 2014 16:05:30
# Last Modified: Mon 29 Dec 2014 01:21:58
# Maintainer:    sharlatan, <sharlatanus@gmail.com>
# License:       Same as Python (GPL)
# Credits:       www.toster.ru/q/166037
#
"""
-=[ Description
The idea of this script (Scr) is taken from www.toster.ru. We give  to the Scr
file of names.txt (more then 1kk lines, file of cities.txt (up to 100) and
numbert in some range. 
Create files from cities.txt and copy random <lines> from <source> to them.

"""


import os
import sys
from random import randint


LOC_PATH = "out_log"
if not os.path.exists(LOC_PATH):
    os.makedirs(LOC_PATH)


def mk_f(dir_name, stuff):
    # Create <dir_name> in <LOC_PATH> with <names.txt> fild with <stuff>
    path_to_bask = os.getcwd()
    new_path = os.path.join(LOC_PATH, dir_name)
    os.makedirs(new_path)
    os.chdir(new_path)

    with open('names.txt', 'w') as f:
        for c in stuff:
            f.write("%s\n" % c)
        f.close()
    os.chdir(path_to_bask)


def read_f(file_in):
    # Read file and retun list of lines without empty items
    with open(file_in, 'r') as f:
        file_out = f.read().split('\n')
    return file_out[:-1]


def rnd_chunk(into_list, min_piece, max_piece):
    # Return random lines from <into_list> withing given range
    out_list = []
    item_quantity = randint(min_piece, max_piece)
    into_list_len = len(into_list)
    while True:
        if len(out_list) != item_quantity:
            put_in = into_list[randint(0,into_list_len-1)]
            if put_in not in out_list:
                out_list.append(put_in)
        else:
            return out_list


def usage():
    #  Show the usage of the script
    file_name = sys.argv[0]
    print ("""\nIncorrect quantity of arguments given or unexisting files
Usage: %s <source file> <cities file> <lines MIN-MAX>\n""" % file_name)


def main():
    """
    Check arguments, for quantity given, for existence of files, for given
    length of <lines>
    """
    if len(sys.argv) != 4:
        usage()
        quit()
    elif os.path.isfile(sys.argv[1]) != True \
       or os.path.isfile(sys.argv[2]) != True:
        usage()
        quit()

    # Take all varialbe from argv
    GET_PIEACE = sys.argv[3].split("-")
    PIECE_MIN = int(GET_PIEACE[0])
    PIECE_MAX = int(GET_PIEACE[1])
    CITIES = read_f(sys.argv[2])
    SOURCE = read_f(sys.argv[1])

    for city_name in CITIES:
        mk_f(city_name, rnd_chunk(SOURCE, PIECE_MIN, PIECE_MAX))

if __name__ == '__main__':
    main()