Jord

jord.py

import hashlib
from math import ceil, log


BASE64_CHARS = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"


def is_jord(n):
    """
    A useless music theory concept, the 'jord' is a sequence of notes where if
    the scale degrees of each note are concatenated as base 10 digits, and the
    resultant number is passed into this function, the result will be True
    """

    # number cannot be negative
    if n <= 0:
        return False

    # no scale degree 0
    if '0' in str(n):
        return False

    # calculate the minimum number of bytes necessary to encode the number
    encoding_length = ceil(log(n, 256))
    # for powers of 256 and rounding errors
    if not 256 ** encoding_length > n:
        encoding_length += 1

    hash_result = int(hashlib.sha256(int(n).to_bytes(encoding_length, 'big', signed=False)).hexdigest(), 16)

    return BASE64_CHARS[hash_result % 64].lower() == 'j' # this could just check for `hash_result % 64 in [9, 35]` but the reasoning is more clear this way