Simple MIT-licensed Dungeons and Dragons encounter calculator written in python

encounters.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
# Copyright © 2018 Taylor C. Richberger <taywee@gmx.com>
# This code is released under the MIT license

import locale
import argparse
from collections import namedtuple

Threshold = namedtuple('Threshold', ['easy', 'medium', 'hard', 'deadly'])

THRESHOLDS = {
    1: Threshold(easy=25, medium=50, hard=75, deadly=100),
    2: Threshold(easy=50, medium=100, hard=150, deadly=200),
    3: Threshold(easy=75, medium=150, hard=225, deadly=400),
    4: Threshold(easy=125, medium=250, hard=375, deadly=500),
    5: Threshold(easy=250, medium=500, hard=750, deadly=1100),
    6: Threshold(easy=300, medium=600, hard=900, deadly=1400),
    7: Threshold(easy=350, medium=750, hard=1100, deadly=1700),
    8: Threshold(easy=450, medium=900, hard=1400, deadly=2100),
    9: Threshold(easy=550, medium=1100, hard=1600, deadly=2400),
    10: Threshold(easy=600, medium=1200, hard=1900, deadly=2800),
    11: Threshold(easy=800, medium=1600, hard=2400, deadly=3600),
    12: Threshold(easy=1000, medium=2000, hard=3000, deadly=4500),
    13: Threshold(easy=1100, medium=2200, hard=3400, deadly=5100),
    14: Threshold(easy=1250, medium=2500, hard=3800, deadly=5700),
    15: Threshold(easy=1400, medium=2800, hard=4300, deadly=6400),
    16: Threshold(easy=1600, medium=3200, hard=4800, deadly=7200),
    17: Threshold(easy=2000, medium=3900, hard=5900, deadly=8800),
    18: Threshold(easy=2100, medium=4200, hard=6300, deadly=9500),
    19: Threshold(easy=2400, medium=4900, hard=7300, deadly=10900),
    20: Threshold(easy=2800, medium=5700, hard=8500, deadly=12700),
}

MULTIPLIERS = [0.5, 1, 1.5, 2, 2.5, 3, 4, 5]
MULTIPLIER_SELECTOR = [0, 1, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5]

def multiplier(playercount, monstercount):
    '''Find the multiplier based on the player count and monster count'''

    if monstercount > 15:
        monstercount = 15
    monstercount -= 1

    index = MULTIPLIER_SELECTOR[monstercount]

    if playercount < 3:
        index += 2
    elif playercount < 6:
        index += 1

    return MULTIPLIERS[index]

def party_threshold(levels):
    '''Calculate the total difficulty threshold based on player levels'''

    easy = 0
    medium = 0
    hard = 0
    deadly = 0

    for level in levels:
        threshold = THRESHOLDS[level]
        easy += threshold.easy
        medium += threshold.medium
        hard += threshold.hard
        deadly += threshold.deadly
    return Threshold(easy, medium, hard, deadly)
    

def main():
    parser = argparse.ArgumentParser(description='Help calculate encounter difficulty')
    parser.add_argument('-V', '--version', action='version', version='0.1')
    parser.add_argument('-m', '--monster', dest='monsters', help='The monster experiences, for calculating difficulty', type=int, nargs='*', default=None)
    parser.add_argument('levels', help='The player levels, required', type=int, nargs='+')
    args = parser.parse_args()

    threshold = party_threshold(args.levels)

    print('Difficulty level experience thresholds for party:')
    print('{:6} {:6} {:6} {:6}'.format('easy', 'medium', 'hard', 'deadly'))
    print('{:6} {:6} {:6} {:6}'.format(threshold.easy, threshold.medium, threshold.hard, threshold.deadly))
    print()

    if args.monsters:
        total_monster_exp = sum(args.monsters)
        mult = multiplier(playercount=len(args.levels), monstercount=len(args.monsters))
        modified_monster_exp = total_monster_exp * mult
        if modified_monster_exp > threshold.deadly:
            difficulty = 'deadly'
        elif modified_monster_exp > threshold.hard:
            difficulty = 'hard'
        elif modified_monster_exp > threshold.medium:
            difficulty = 'medium'
        elif modified_monster_exp > threshold.easy:
            difficulty = 'easy'
        else:
            difficulty = 'trivial'

        print('Combined monster experience is {}'.format(total_monster_exp))
        print('Is multiplied by {} to become {}'.format(mult, modified_monster_exp))
        print('This encounter is {}'.format(difficulty))
    else:
        print('Total experience for difficulty based on monster count:')
        print('{:>2}: {:6} {:6} {:6} {:6}'.format('#', 'easy', 'medium', 'hard', 'deadly'))
        for count in range(1, 16):
            mult = multiplier(playercount=len(args.levels), monstercount=count)
            print('{:>2}: {:6} {:6} {:6} {:6}'.format(
                count,
                round(threshold.easy / mult),
                round(threshold.medium / mult),
                round(threshold.hard / mult),
                round(threshold.deadly / mult),
            ))
        print()

        print('Average per-monster experience for same table:')
        print('{:>2}: {:6} {:6} {:6} {:6}'.format('#', 'easy', 'medium', 'hard', 'deadly'))
        for count in range(1, 16):
            mult = multiplier(playercount=len(args.levels), monstercount=count)
            print('{:>2}: {:6} {:6} {:6} {:6}'.format(
                count,
                round(threshold.easy / mult / count),
                round(threshold.medium / mult / count),
                round(threshold.hard / mult / count),
                round(threshold.deadly / mult / count),
            ))

if __name__ == '__main__':
    locale.setlocale(locale.LC_ALL, '')
    main()