Coding dojo in Minsk session result for 2019-02-03

digital.py

"""
See https://www.codewars.com/kata/digital-cypher
"""

import itertools
import string

ABC = string.ascii_lowercase


def build_abc_map(abc):
    """
    >>> build_abc_map('abc')
    {'a': 1, 'c': 3, 'b': 2}
    """
    result = {alpha: index for index, alpha in enumerate(abc, 1)}
    return result


def encode(text, key):
    """
    >>> encode("scout", 1939)
    [20, 12, 18, 30, 21]
    >>> encode("masterpiece", 1939)
    [14, 10, 22, 29, 6, 27, 19, 18, 6, 12, 8]
    """
    abc_dict = build_abc_map(ABC)
    key_str = str(key)
    infinite_key = itertools.cycle(key_str)
    return [
        abc_dict[char] + int(offset)
        for char, offset in zip(text, infinite_key)
    ]


def encode_by_string(text, key_str):
    """
    >>> encode_by_string("scout", "a")
    'tdpvu'
    """
    abc_dict = build_abc_map(ABC)
    numeric_dict = {value: key for key, value in abc_dict.items()}
    infinite_key = itertools.cycle(key_str)
    return ''.join([
        numeric_dict[(abc_dict[char] + abc_dict[offset]) % len(numeric_dict)]
        for char, offset in zip(text, infinite_key)
    ])