Backtest IMC Prosperity 2023

This is repo contains utilities for IMC Prosperity 2023 challenge. Right now, it has the backtester.py, that should mimic log files from the prosperity challenge platform. The format is good enough to be accepted by jmerle's amazing project, for visualizing the order book as well as your trades.

Order matching

Orders returned by the Trader.run method, are matched against the OrderDepth of the state provided to the method call. The trader always gets their trade and trades from bots are ignored. An order is matched only if the price is exactly the same as an opposite one from OrderDepth. If the new position that would result from this order exceeds the specified limit of the symbol, all following orders (including the failing one) are cancelled. You can relax those conditions by answering sth. to Matching orders halfway (sth. not blank for True):, during the input dialog of the backtester. Halfway matches any volume (regardless of order book), such that sell/buy orders are always matched, if they're below/above the midprice of the highest bid/lowest ask (regardless of volume). If an order couldn't be matched the backtester will look the current order depth and your unmatched order.

After All

If your trader has a method called after_last_round, it will be called after the logs have been written. This is useful for plotting something with matplotlib for example (but don't forget to remove the import, when you upload your algorithm).

General usage

Add the csv's from IMC to the training folder and adjust if necessary the constant TRAINING_DATA_PREFIX to the full path of training directory on your system, at the top of backtester.py. Import your Trader at the top of backtester.py (in the repo the Trader from dontlooseshells.py is used). Then run

python backtester.py

This executes

if __name__ == "__main__":
    trader = Trader()
    simulate_alternative(3, 0, trader, False, 30000)

The central method is simulate_alternative. There are some default parameters and the meaning is

def simulate_alternative(
        round: int, 
        day: int, 
        trader, 
        time_limit=999900, 
        names=True, 
        halfway=False,
        monkeys=False,
        monkey_names=['Max', 'Camilla']
    ):

where round and day are substituted to the following path {TRAINING_DATA_PREFIX}/prices_round_{round}_day_{day}.csv (same for trades_round...). Trader is your algorithm trader, time_limit can be decreased to only read a part of the full training file. names reads the training files with names on market_trades. halfway enables smarter order matching. The last two are a secret, that you might want to checkout for yourself.

Logging with jmerle's visualizer

Because the backtester doesn't read from the stdout nor stderr, logs produced have an empty Submission logs: section (still limit exceeds are printed). Furthermore the default Logger from jmerle's project won't do the trick, the following adjustments make it compatible

class Logger:
    # Set this to true, if u want to create
    # local logs
    local: bool 
    # this is used as a buffer for logs
    # instead of stdout
    local_logs: dict[int, str] = {}

    def __init__(self, local=False) -> None:
        self.logs = ""
        self.local = local

    def flush(self, state: TradingState, orders: dict[Symbol, list[Order]]) -> None:
        output = json.dumps({
            "state": self.compress_state(state),
            "orders": self.compress_orders(orders),
            "logs": self.logs,
        }, cls=ProsperityEncoder, separators=(",", ":"), sort_keys=True))

        if self.local:
            self.local_logs[state.timestamp] = output

        print(out)
        self.logs = ""
# ... And the rest of the compression logic

and in your Trader class add the attribute like this:

class Trader:

    logger = Logger(local=True)

Now calls to self.logger.flush will be visible in the log files and available to the visualizer. Thus it can also provide you diagrams about prices, volumes etc. A working example is given in dontlooseshells.py.

Profit and Loss (PnL)

PnL is maintained via four time series

• profits_by_symbol (the final pnl)
• balance_by_symbol: (credit_by_symbol + unrealized_by_symbol)
• credit_by_symbol: (the amount of credit you had to take to open up the position (opposite sign of trade.quantity))
• unrealized_by_symbol: (the approximated value (mid price) if you would close the position at this point in time) PnL is calculated if your position of some asset is changed to 0, by a trade. Until then credit_by_symbol holds the amount of the previous executed trades and the amount of seashells you borrowed (both short and long require borrowing Because you're not trading on the profits or some initial balance of your previous competition rounds). On closing your whole position credit_by_symbol will only contain the pnl and is added to profits_by_symbol. This would not give you enough information to evaluate your current portfolio between trades, hence the need for balance_by_symbol. For the logger file balance_by_symbol is added to profits_by_symbol, which gives similar values to the simulation. Be aware that the IMC environment matches more trades, than the backtester, thus the final values might be different. But if exactly the same trades would be executed then both give the same results.

The value of an executed trade is:

current_pnl += -trade.price * trade.quantity

Meaning that if the trade was selling a symbol (e.g. Shorting) the trade.quantity is negative , ending in a positive current_pnl. Hence buying a symbol is a positive trade.quantity, ending in a negative current_pnl.

Good luck 🍀