Convert any positive integer into a DNS like name and vice-versa

namji.py

#!/usr/bin/env python2

#
# Copyright 2017 Science & Technology Facilities Council
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

"""
Convert any positive integer into a DNS style name and vice-versa.

A text file named 'elements' with a single unique word per line must be supplied, census birth name data works well.
"""

import argparse

SEPERATOR = '.'

# From https://stackoverflow.com/questions/2267362/how-to-convert-an-integer-in-any-base-to-a-string
def number_to_base(n, b):
    if n == 0:
        return [0]
    digits = []
    while n:
        digits.append(int(n % b))
        n //= b
    return digits[::-1]


def get_elements():
    result = open('elements').readlines()
    result = [s.strip().lower() for s in result]
    return result


def number_to_name(num, elements):
    result = []
    for val in number_to_base(num, len(elements)):
        result.append(elements[val])
    result.reverse()
    return SEPERATOR.join(result)


def name_to_number(name, elements):
    numbers = []
    words = name.strip().lower().split(SEPERATOR)

    for word in words:
        numbers.append(elements.index(word))

    result = 0
    for power, number in enumerate(numbers):
        result += number * (len(elements) ** power)
    return result


def int_positive(s):
    i = int(s)
    if i < 0:
        raise argparse.ArgumentTypeError("must be a positive integer")
    return i


def main():
    parser = argparse.ArgumentParser(description='Namji')
    parser.add_argument('-n', type=int_positive, help='Number to convert to text')
    parser.add_argument('-t', type=str, help='Text to convert to number')
    args = parser.parse_args()

    if args.n is not None or args.t is not None:
        elements = get_elements()

        if args.n is not None:
            print '%d\t%s' % (args.n, number_to_name(args.n, elements))

        if args.t is not None:
            print '%s\t%d' % (args.t, name_to_number(args.t, elements))


if __name__ == '__main__':
    main()