Files
tick-stock-panel/backend/app/backtest/walkforward.py
T
im47cn e4262d9951 fix(walkforward): IS 训练折强制 position 模式, 堵前视泄漏
对抗式审查发现: WF UI 暴露 full 模式, 选中时训练折(end=train_end)未平仓的持仓
会用 train_end 之后(即 OOS 区间)的真实 K 线平仓 -> IS 分数被未来数据污染, 优化选出
的最优参数乐观偏移, 使过拟合被掩盖 (对专门检测过拟合的 WF 工具危害尤重)。

修复: IS 训练区间优化强制 mode="position" (只看正式区间表现), OOS 回测保留用户
所选 mode。新增测试: 用户选 full 时断言每折 IS 得到 position、OOS 保留 full。
2026-07-12 21:48:13 +08:00

283 lines
11 KiB
Python

"""Walk-forward 优化 — 滚动窗口的样本内优化 + 样本外验证。
每折在训练区间用参数网格优化选出最优参数, 再在紧邻的测试区间用该参数做样本外(OOS)
回测。滚动前移。核心产出是 OOS 拼接净值 + 每折 IS-vs-OOS 退化 —— 样本内漂亮、样本外
崩溃即过拟合信号, 单次样本内回测看不到。
依赖 PR2a 的 StrategyOptimizer 做每折训练区间的网格优化。
"""
from __future__ import annotations
import logging
import time
from dataclasses import dataclass, field
from datetime import date, timedelta
logger = logging.getLogger(__name__)
@dataclass
class Fold:
index: int
train_start: date
train_end: date
test_start: date
test_end: date
def generate_folds(
start: date,
end: date,
train_days: int,
test_days: int,
step_days: int,
) -> list[Fold]:
"""滚动窗口 fold 切分: 训练窗口固定长度, 测试窗口紧接其后, 按 step 前移。
测试区间超出 end 即停止。数据区间放不下一折则抛错。
"""
if train_days <= 0 or test_days <= 0 or step_days <= 0:
raise ValueError("train_days / test_days / step_days 必须为正")
folds: list[Fold] = []
i = 0
train_start = start
while True:
train_end = train_start + timedelta(days=train_days)
# 测试区间从训练末日的次日开始: 回测区间是闭区间, 若 test_start==train_end 则
# 该日 K 线同时进训练优化与 OOS 首日, 构成前视泄漏。后移一天隔断。
test_start = train_end + timedelta(days=1)
test_end = test_start + timedelta(days=test_days)
if test_end > end:
break
folds.append(Fold(i, train_start, train_end, test_start, test_end))
i += 1
train_start = train_start + timedelta(days=step_days)
if not folds:
raise ValueError(
f"数据区间不足以切出至少一折 (需 train+test={train_days + test_days}天, "
f"实有 {(end - start).days}天)"
)
return folds
def _norm(v: float, direction: str) -> float:
"""把目标值归一到"越大越好"空间, 以便跨目标一致地算退化 (min 类目标取负)。"""
return -v if direction == "min" else v
def aggregate_oos(fold_records: list[dict], objective: str, direction: str = "max") -> dict:
"""从**有效折** (IS 与 OOS 都成功) 聚合: 复利净值 / IS-OOS 退化 / 一致性。
调用方只传有效折 (best_params 非空且 OOS 未 error), 故此处每折 is_score/oos_objective
均有值, 无需 .get 默认兜底 —— 无效折被伪装成 0 收益混入曾是 H1/H2 的根因。
- compounded_oos_return: 各折 OOS 总收益复利
- degradation: 归一空间下 IS 目标均值 - OOS 目标均值, 正值 = 样本外退化 (过拟合信号),
对"越小越好"目标 (max_drawdown 等) 方向也正确
- consistency: OOS 总收益 > 0 的折占比 (与目标方向无关, 直观)
"""
n = len(fold_records)
if n == 0:
return {
"n_folds": 0,
"compounded_oos_return": 0.0,
"avg_is_objective": None,
"avg_oos_objective": None,
"degradation": None,
"consistency": 0.0,
"oos_equity_curve": [],
}
equity = 1.0
curve: list[dict] = []
n_positive = 0
for f in fold_records:
r = float(f["oos_stats"].get("total_return", 0.0) or 0.0)
equity *= (1 + r)
if r > 0:
n_positive += 1
curve.append({"fold": f["index"], "date": str(f["test_end"]), "value": round(equity, 4)})
is_vals = [f["is_score"] for f in fold_records if f["is_score"] is not None]
oos_vals = [f["oos_objective"] for f in fold_records if f["oos_objective"] is not None]
avg_is = round(float(sum(is_vals) / len(is_vals)), 4) if is_vals else None
avg_oos = round(float(sum(oos_vals) / len(oos_vals)), 4) if oos_vals else None
degradation = (
round(_norm(avg_is, direction) - _norm(avg_oos, direction), 4)
if (avg_is is not None and avg_oos is not None) else None
)
return {
"n_folds": n,
"compounded_oos_return": round(equity - 1.0, 4),
"avg_is_objective": avg_is,
"avg_oos_objective": avg_oos,
"degradation": degradation,
"consistency": round(n_positive / n, 4),
"oos_equity_curve": curve,
}
@dataclass
class WalkForwardConfig:
strategy_id: str
symbols: list[str] | None
start: date
end: date
param_grid: dict
objective: str = "sortino"
train_days: int = 252
test_days: int = 63
step_days: int = 63
direction: str | None = None
max_workers: int = 4
base_params: dict = field(default_factory=dict)
overrides: dict | None = None
backtest_kwargs: dict = field(default_factory=dict)
class WalkForwardService:
"""滚动窗口 walk-forward: 每折训练区间优化 -> 测试区间 OOS 验证 -> 聚合。"""
def __init__(self, optimizer, service, strategy_engine) -> None:
self.optimizer = optimizer
self.service = service
self.strategy_engine = strategy_engine
def run(
self,
cfg: WalkForwardConfig,
progress_cb=None,
cancel_event=None,
) -> dict:
from app.backtest.optimizer import OptimizeConfig, default_direction
from app.backtest.strategy import StrategyBacktestConfig
t0 = time.perf_counter()
direction = cfg.direction or default_direction(cfg.objective)
folds = generate_folds(cfg.start, cfg.end, cfg.train_days, cfg.test_days, cfg.step_days)
n_total = len(folds)
# 遥测: 首尾快照 PanelCache, 量化跨折重叠区间重复扫盘的 IO 占比 (是否值得进一步优化)。
cache_before = self.service.engine.cache_stats()
valid_records: list[dict] = [] # IS 与 OOS 都成功, 计入聚合
skipped: list[dict] = [] # 无优化结果 或 OOS 失败, 不计入聚合 (避免伪装成有效折)
done = 0
# IS 训练区间强制 position 模式: full 模式会让训练折未平仓持仓用 train_end 之后
# (即 OOS 区间) 的真实 K 线平仓, IS 分数被未来数据污染 -> 优化选参乐观偏移, 使过拟合
# 被掩盖。OOS 回测保留用户所选 mode。参数扫描优化只看正式区间内的表现即可。
is_backtest_kwargs = {**cfg.backtest_kwargs, "mode": "position"}
for f in folds:
if cancel_event is not None and cancel_event.is_set():
break
# 训练区间: 网格优化选最优参数
opt_cfg = OptimizeConfig(
strategy_id=cfg.strategy_id,
symbols=cfg.symbols,
start=f.train_start,
end=f.train_end,
param_grid=cfg.param_grid,
objective=cfg.objective,
direction=cfg.direction,
max_workers=cfg.max_workers,
base_params=cfg.base_params,
overrides=cfg.overrides,
backtest_kwargs=is_backtest_kwargs, # IS 强制 position, 堵前视泄漏
)
opt_res = self.optimizer.optimize(opt_cfg, cancel_event=cancel_event)
best_params = opt_res.get("best_params")
is_score = opt_res.get("best_score")
done += 1
base = {
"index": f.index,
"train_start": str(f.train_start),
"train_end": str(f.train_end),
"test_start": str(f.test_start),
"test_end": str(f.test_end),
}
# 训练区间没优化出参数 (全组失败/取消) -> 跳过, 不用默认参数硬跑 OOS 伪装成有效折
if best_params is None:
skipped.append({**base, "reason": "训练区间未优化出参数"})
if progress_cb is not None:
progress_cb({"type": "walkforward_progress", "done": done, "total": n_total, "fold": f.index})
continue
# 测试区间: 用最优参数做样本外回测
merged = {**cfg.base_params, **best_params}
oos_cfg = StrategyBacktestConfig(
strategy_id=cfg.strategy_id,
symbols=cfg.symbols,
start=f.test_start,
end=f.test_end,
params=merged,
overrides=cfg.overrides,
**cfg.backtest_kwargs,
)
oos_res = self.service.run(oos_cfg, cancel_event=cancel_event)
# OOS 失败 (含 cancelled) -> 跳过, 不把空/0 收益混入复利曲线
if oos_res.error:
skipped.append({**base, "best_params": best_params, "reason": f"OOS 回测失败: {oos_res.error}"})
if progress_cb is not None:
progress_cb({"type": "walkforward_progress", "done": done, "total": n_total, "fold": f.index})
continue
oos_objective = oos_res.stats.get(cfg.objective)
# 该折 OOS 是否较 IS 退化 (方向感知: min 类目标数值更大才是退化)
oos_degraded = (
_norm(oos_objective, direction) < _norm(is_score, direction)
if (oos_objective is not None and is_score is not None) else None
)
valid_records.append({
**base,
"best_params": best_params,
"is_score": is_score,
"oos_objective": oos_objective,
"oos_degraded": oos_degraded,
"oos_stats": oos_res.stats,
})
if progress_cb is not None:
progress_cb({"type": "walkforward_progress", "done": done, "total": n_total, "fold": f.index})
summary = aggregate_oos(valid_records, cfg.objective, direction)
# 遥测收尾: 本次 WF 累计扫盘耗时 / 命中 / 复用, 与总耗时对比得出 load_panel 占比。
cache_after = self.service.engine.cache_stats()
elapsed_ms = round((time.perf_counter() - t0) * 1000, 1)
io_seconds = round(cache_after["compute_seconds"] - cache_before["compute_seconds"], 4)
io_pct = round(io_seconds * 1000 / elapsed_ms * 100, 1) if elapsed_ms > 0 else 0.0
cache_telemetry = {
"load_panel_seconds": io_seconds,
"load_panel_pct": io_pct, # 扫盘耗时 / WF 总耗时
"scans": cache_after["compute_count"] - cache_before["compute_count"],
"hits": cache_after["hit_count"] - cache_before["hit_count"],
"single_flight_reuses": cache_after["reuse_count"] - cache_before["reuse_count"],
}
logger.info(
"walk-forward IO 占比: load_panel %.3fs (%.1f%% of %.1fms) | 扫盘 %d 次 命中 %d 复用 %d",
io_seconds, io_pct, elapsed_ms,
cache_telemetry["scans"], cache_telemetry["hits"], cache_telemetry["single_flight_reuses"],
)
return {
"objective": cfg.objective,
"direction": direction,
"n_folds": len(valid_records),
"n_skipped": len(skipped),
"n_planned_folds": n_total,
"folds": valid_records,
"skipped": skipped,
"summary": summary,
"cache_telemetry": cache_telemetry,
"elapsed_ms": elapsed_ms,
}