Generate random string

randstr.py

#!/usr/bin/python3

import string
import random
import itertools
import argparse

IDENT_FIRST = string.ascii_letters + '_'
IDENT_LAST = string.ascii_letters + string.digits + '_'


def pick(char_set, count=1):
    return ''.join([random.choice(char_set) for _ in range(count)])


def chunk(xs, n):
    ys = list(xs)
    random.shuffle(ys)
    size = len(ys) // n
    leftovers = ys[size*n:]
    for c in range(n):
        if leftovers:
            extra = [leftovers.pop()]
        else:
            extra = []
        yield ys[c*size:(c+1)*size] + extra


def gen_password(count=12):
    lens = list(chunk(range(count), 4))
    lower = len(lens[0])
    upper = len(lens[1])
    number = len(lens[2])
    special = len(lens[3])
    lower_str = [pick(string.ascii_lowercase) for _ in range(lower)]
    upper_str = [pick(string.ascii_uppercase) for _ in range(upper)]
    number_str = [pick(string.digits) for _ in range(number)]
    special_str = [pick(string.punctuation) for _ in range(special)]
    l = list(itertools.chain.from_iterable(
        lower_str + upper_str + number_str + special_str))
    random.shuffle(l)
    return ''.join(l)


result = ''
parser = argparse.ArgumentParser(description='Process some integers.')
parser.add_argument('-c', '--count', dest='count', metavar='N', type=int, default=10,
                    help='number of the letters')
parser.add_argument('-u', '--upper', dest='upper', action='store_true',
                    help='uppercase letters only')
parser.add_argument('-l', '--lower', dest='lower', action='store_true',
                    help='lowercase letters only')
parser.add_argument('-n', '--number', dest='number', action='store_true',
                    help='include numbers')
parser.add_argument('-i', '--ident', dest='ident', action='store_true',
                    help='generate an identifier')
parser.add_argument('-p', '--password', dest='password', action='store_true',
                    help='generate a password')

args = parser.parse_args()
if args.ident:
    result = pick(IDENT_FIRST) + pick(IDENT_LAST, args.count-1)
elif args.password:
    result = gen_password(args.count)
elif args.upper:
    if args.number:
        result = pick(string.ascii_uppercase + string.digits, args.count)
    else:
        result = pick(string.ascii_uppercase, args.count)
elif args.lower:
    if args.number:
        result = pick(string.ascii_lowercase + string.digits, args.count)
    else:
        result = pick(string.ascii_lowercase, args.count)
elif args.number:
    result = pick(string.ascii_letters + string.digits, args.count)
else:
    result = pick(string.ascii_letters, args.count)
print(result)