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src/mcm26b/sim/scenes.py

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+"""自检场景生成器（测试端专用）。
+
+真值只进入测试与 CLI ``--self-test`` 入口，策略端仅见模拟器响应；
+场景覆盖题面强调的边界情形：近圆域边界源、最小/最大接收半径两档，
+以及问题4的定向源（含朝向背离圆心的朝外边界源）。
+"""
+
+from __future__ import annotations
+
+import math
+from random import Random
+
+from .simulator import Source
+
+
+def random_omni_scene(seed: int = 20260910, count: int = 10) -> list[Source]:
+    """全向源场景：频道互异，含近圆域边界点，接收半径 1000/1500 交替。"""
+    if not 0 <= count <= 20:
+        raise ValueError("源数量须在 0..20")
+    rng = Random(seed)
+    channels = rng.sample(range(1, 21), count)
+    sources = []
+    for index, channel in enumerate(channels):
+        if index == 0:
+            radius = rng.uniform(1780.0, 1799.0)      # 近圆域边界
+        elif index == 1 and count > 1:
+            radius = rng.uniform(1780.0, 1799.0)
+        else:
+            radius = rng.uniform(0.0, 1795.0)
+        angle = rng.uniform(0.0, 2 * math.pi)
+        r_eff = 1000.0 if index % 2 == 0 else 1500.0
+        sources.append(Source(channel=channel,
+                              x=radius * math.cos(angle),
+                              y=radius * math.sin(angle),
+                              r_eff_m=r_eff))
+    return sources
+
+
+def mixed_scene(seed: int = 20260910, count: int = 10,
+                directional: int = 3) -> list[Source]:
+    """问题4混合场景：count 个源中 directional 个为定向源。
+
+    改造 random_omni_scene 的前 directional 个源：近圆域边界的前两个定向源
+    朝向取"背离圆心"（发射半平面基本朝向域外，覆盖网格仍保证可发现，
+    即"朝外边界源不漏"验收情形），其余定向源朝向随机。
+    """
+    if not 0 <= directional <= count:
+        raise ValueError("定向源数量须在 0..count")
+    sources = list(random_omni_scene(seed=seed, count=count))
+    rng = Random(seed + 1)
+    for index in range(directional):
+        source = sources[index]
+        if index < 2 and count > 1 and math.hypot(source.x, source.y) > 1700.0:
+            heading = math.degrees(math.atan2(source.y, source.x)) % 360.0
+        else:
+            heading = rng.uniform(0.0, 360.0)
+        sources[index] = source.__class__(channel=source.channel, x=source.x,
+                                          y=source.y, r_eff_m=source.r_eff_m,
+                                          directional=True, heading_deg=heading)
+    return sources