Calculate the probability of a reward in R6 Siege

r6.py

#! /usr/bin/env python3

"""Simulate the probability of a reward in R6 Siege."""

from argparse import ArgumentParser
import random
from textwrap import dedent
from typing import Mapping


BASE_PROBABILITY: float = 0.02
"""The initial/reset/increment probability of a reward on a win."""

VIP_BONUS_PROBABILITY: float = 0.003
"""The bonus probability you get from VIP status."""


def siege_rewards(
    *,
    win_loss: float=1.,
    vip: bool=False,
    matches: int=1_000_000,
    per_win: bool=False,
) -> float:
    """Per-match or per-win probability of receiving an award."""
    reward_probability = BASE_PROBABILITY
    win_probability = win_loss / (1 + win_loss)
    wins = 0
    rewards = 0
    for _ in range(matches):
        if vip:
            reward_probability += VIP_BONUS_PROBABILITY
        if random.random() < win_probability:
            wins += 1
            if random.random() < reward_probability:
                rewards += 1
                reward_probability = BASE_PROBABILITY
                continue
        reward_probability += BASE_PROBABILITY
    return rewards / (wins if per_win else matches)


def _create_parser() -> ArgumentParser:
    """Create the parser for command-line arguments."""
    parser = ArgumentParser(description=__doc__)
    parser.add_argument(
        "-w",
        "--win-loss",
        type=float,
        default=1.,
        help="your ratio of wins to losses",
    )
    parser.add_argument(
        "-v",
        "--vip",
        action="store_true",
        help="whether you have VIP status (bonus 0.3%% probability)",
    )
    parser.add_argument(
        "-m",
        "--matches",
        type=int,
        default=1_000_000,
        help="number of matches to simulate",
    )
    parser.add_argument(
        "-p",
        "--per-win",
        action="store_true",
        help="whether to calculate per win, rather than per match",
    )
    return parser


def _get_arg_help(parser: ArgumentParser) -> Mapping[str, str]:
    """Get the help text for the defined optional arguments."""
    return {
        action.dest: action.help % ()
        for action in parser._action_groups[1]._actions
    }


if __name__ == "__main__":
    ARGS = _create_parser().parse_args()
    REWARD_PROBABILITY = siege_rewards(**vars(ARGS))
    print(f"{REWARD_PROBABILITY * 100:.2f}%")
else:
    siege_rewards.__doc__ = dedent(
        """{}

        Arguments:
          win_loss: {win_loss}
          vip: whether {vip}
          matches: {matches}
          per_win: {per_win}

        """.format(
            siege_rewards.__doc__,
            **_get_arg_help(_create_parser()),
        ),
    )