33 lines
1.1 KiB
Python
33 lines
1.1 KiB
Python
"""England boundary polygon for accurate point-in-country filtering.
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Uses shapely prepared geometry for fast single-point checks (osmium handlers)
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and vectorized shapely.contains for batch checks (Polars DataFrames).
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"""
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import json
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from pathlib import Path
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import numpy as np
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import shapely
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from shapely.geometry import shape
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from shapely.prepared import PreparedGeometry, prep
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def load_england_polygon(geojson_path: Path) -> PreparedGeometry:
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"""Load England boundary as a prepared shapely polygon for fast contains checks."""
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with open(geojson_path) as f:
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data = json.load(f)
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geometry = shape(data["features"][0]["geometry"])
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return prep(geometry)
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def in_england_mask(geojson_path: Path, lats: np.ndarray, lngs: np.ndarray) -> np.ndarray:
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"""Vectorized check: which (lat, lng) points are within England.
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Returns a boolean numpy array.
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"""
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with open(geojson_path) as f:
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data = json.load(f)
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polygon = shape(data["features"][0]["geometry"])
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pts = shapely.points(lngs, lats)
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return shapely.contains(polygon, pts)
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