Files
wickra/examples/python/live_trading.py
T
kingchenc a8fb0b8181 C12: fix falsy-value display and validate symbol/interval
Two issues in the live_trading example:

- The status line rendered indicator values with `... if snap.rsi
  else "--"`. A genuine reading of 0.0 is falsy, so an RSI / MACD
  histogram / Bollinger value of exactly zero was misreported as "--".
  Switch to explicit `is not None` checks.

- --symbol and --interval were interpolated straight into the stream
  name and WebSocket URL with no checks. Add validate_args: the symbol
  must be strictly alphanumeric and the interval must be one Binance
  recognises. main() validates before connecting and exits with a clear
  error and code 2 otherwise; the strict values keep the URL well-formed
  without escaping.
2026-05-22 12:27:13 +02:00

194 lines
6.3 KiB
Python

"""Live trading skeleton: stream Binance kline ticks → incremental indicators → signals.
This example connects to Binance's public WebSocket feed (no API key needed)
and runs RSI / MACD / Bollinger Bands on the close prices coming in. When the
RSI crosses common overbought / oversold thresholds *and* the MACD histogram
confirms the direction, a `Signal` event is printed. No orders are placed.
Run with::
python -m examples.python.live_trading --symbol BTCUSDT --interval 1m
Dependencies::
pip install websockets
"""
from __future__ import annotations
import argparse
import asyncio
import json
import logging
import re
import signal
import sys
from dataclasses import dataclass
from typing import Optional
import wickra as ta
try:
import websockets
except ImportError:
print("This example needs the `websockets` package: pip install websockets", file=sys.stderr)
raise
BINANCE_WS = "wss://stream.binance.com:9443/stream"
# Kline intervals the public Binance WebSocket API recognises.
VALID_INTERVALS = frozenset(
{
"1s", "1m", "3m", "5m", "15m", "30m",
"1h", "2h", "4h", "6h", "8h", "12h",
"1d", "3d", "1w", "1M",
}
)
# A Binance symbol is strictly alphanumeric (e.g. BTCUSDT).
_SYMBOL_RE = re.compile(r"^[A-Za-z0-9]+$")
def validate_args(symbol: str, interval: str) -> None:
"""Reject a symbol or interval that is not safe to splice into the WS URL.
Both values are interpolated straight into the stream name and URL, so an
unexpected value would otherwise produce a confusing connection failure.
Validating up front keeps the URL well-formed without needing to escape it.
Raises:
ValueError: if ``symbol`` is not strictly alphanumeric, or ``interval``
is not one Binance recognises.
"""
if not _SYMBOL_RE.match(symbol):
raise ValueError(
f"invalid --symbol {symbol!r}: expected only letters and digits, "
"e.g. BTCUSDT"
)
if interval not in VALID_INTERVALS:
raise ValueError(
f"invalid --interval {interval!r}: expected one of "
+ ", ".join(sorted(VALID_INTERVALS))
)
@dataclass
class Snapshot:
rsi: Optional[float]
macd_hist: Optional[float]
bb_upper: Optional[float]
bb_middle: Optional[float]
bb_lower: Optional[float]
close: float
class StrategyState:
"""Holds one streaming instance of each indicator and computes signals."""
def __init__(self) -> None:
self.rsi = ta.RSI(14)
self.macd = ta.MACD()
self.bb = ta.BollingerBands(20, 2.0)
def update(self, close: float) -> Snapshot:
rsi = self.rsi.update(float(close))
macd_v = self.macd.update(float(close))
bb_v = self.bb.update(float(close))
return Snapshot(
rsi=rsi,
macd_hist=macd_v[2] if macd_v else None,
bb_upper=bb_v[0] if bb_v else None,
bb_middle=bb_v[1] if bb_v else None,
bb_lower=bb_v[2] if bb_v else None,
close=float(close),
)
def emit_signal(snap: Snapshot, log: logging.Logger) -> None:
if snap.rsi is None or snap.macd_hist is None or snap.bb_upper is None:
return
if snap.rsi > 70 and snap.macd_hist < 0 and snap.close >= snap.bb_upper:
log.warning(
"SELL candidate: rsi=%.1f hist=%.4f close=%.4f >= bb_upper=%.4f",
snap.rsi, snap.macd_hist, snap.close, snap.bb_upper,
)
elif snap.rsi < 30 and snap.macd_hist > 0 and snap.close <= snap.bb_lower:
log.warning(
"BUY candidate: rsi=%.1f hist=%.4f close=%.4f <= bb_lower=%.4f",
snap.rsi, snap.macd_hist, snap.close, snap.bb_lower,
)
async def run(symbol: str, interval: str) -> None:
stream = f"{symbol.lower()}@kline_{interval}"
url = f"{BINANCE_WS}?streams={stream}"
log = logging.getLogger("wickra-live")
state = StrategyState()
log.info("Connecting to %s", url)
async with websockets.connect(url, ping_interval=20) as ws:
log.info("Connected, listening for %s klines", stream)
async for raw in ws:
envelope = json.loads(raw)
payload = envelope.get("data", {})
k = payload.get("k", {})
if not k or "c" not in k:
# Subscription acks, heartbeats and error frames carry no
# kline payload — skip them instead of crashing on
# float(None) the moment the stream opens.
log.debug("skipping non-kline frame: %s", raw)
continue
close = float(k.get("c"))
is_closed = bool(k.get("x"))
snap = state.update(close)
log.info(
"%s close=%.4f rsi=%s hist=%s bb=%s",
"BAR" if is_closed else "tick",
close,
f"{snap.rsi:.1f}" if snap.rsi is not None else "--",
f"{snap.macd_hist:+.4f}" if snap.macd_hist is not None else "--",
f"{snap.bb_lower:.2f}/{snap.bb_middle:.2f}/{snap.bb_upper:.2f}"
if snap.bb_upper is not None
else "--",
)
emit_signal(snap, log)
def parse_args() -> argparse.Namespace:
p = argparse.ArgumentParser(description=__doc__.splitlines()[0] if __doc__ else None)
p.add_argument("--symbol", default="BTCUSDT", help="trading pair")
p.add_argument("--interval", default="1m", help="Binance kline interval")
p.add_argument("--verbose", action="store_true")
return p.parse_args()
def main() -> int:
args = parse_args()
try:
validate_args(args.symbol, args.interval)
except ValueError as exc:
print(f"error: {exc}", file=sys.stderr)
return 2
logging.basicConfig(
level=logging.DEBUG if args.verbose else logging.INFO,
format="%(asctime)s %(levelname)s %(message)s",
)
loop = asyncio.new_event_loop()
# Translate Ctrl+C into a clean loop stop.
for sig in (signal.SIGINT, signal.SIGTERM):
try:
loop.add_signal_handler(sig, loop.stop)
except NotImplementedError:
pass # Windows does not support add_signal_handler for SIGTERM.
try:
loop.run_until_complete(run(args.symbol, args.interval))
except KeyboardInterrupt:
pass
finally:
loop.close()
return 0
if __name__ == "__main__":
sys.exit(main())