Aging calculator

aging_calculator.py

#!/usr/bin/env python3

from datetime import datetime


TARGETS = {
    'Anthony': {
        'dob': datetime(1982, 10, 19),
        'aging_rate': 1
    },
    'Winnie': {
        'dob': datetime(2012, 5, 18),
        'aging_rate': 7    
    }
}

def find_intersect(profileA, profileB):
    lhs = profileA['aging_rate'] - profileB['aging_rate']
    rhs = profileA['aging_rate'] * profileA['dob'].timestamp() - profileB['aging_rate'] * profileB['dob'].timestamp()
    x_value = datetime.fromtimestamp(rhs / lhs)
    y_value = make_fx(profileA)(x_value)
    return (x_value, y_value)

def human_readable(age):
    minute_length = 60
    hour_length = 60 * minute_length
    day_length = 24 * hour_length
    year_length = 365.25 * day_length

    years = int(age / year_length)
    age -= years * year_length

    days = int(age / day_length)
    age -= days * day_length

    hours = int(age / hour_length)
    age -= hours * hour_length

    minutes = int(age / minute_length)

    return '{0}, {1}, {2} and {3}'.format(
        pluralize(years, 'year'),
        pluralize(days, 'day'),
        pluralize(hours, 'hour'),
        pluralize(minutes, 'minute')
    )

def make_fx(aging_profile):
    return lambda x: int(aging_profile['aging_rate'] * (x.timestamp() - aging_profile['dob'].timestamp()))

def pluralize(number, word, plural='s'):
    return '{0} {1}{2}'.format(number, word, ('' if number == 1 else plural))


if __name__ == '__main__':
    for (name, aging_profile) in TARGETS.items():
        # let y represent age
        # let x represent date
        # let m represent aging rate
        # let b represent date of birth
        #
        # y = m(x - b)

        age = make_fx(aging_profile)
        now_age = age(datetime.now())

        print('{0}\'s age now is: {1}'.format(name, human_readable(now_age)))

    names = ' and '.join(TARGETS.keys())
    intersection = find_intersect(*TARGETS.values())

    print('{0}\'s age will intersect on {1}. They will both be {2} old.'.format(names, intersection[0], human_readable(intersection[1])))