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49 lines
1.5 KiB
Python
49 lines
1.5 KiB
Python
# SPDX-License-Identifier: GPL-3.0-or-later
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#
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# This file is part of Nominatim. (https://nominatim.org)
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#
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# Copyright (C) 2024 by the Nominatim developer community.
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# For a full list of authors see the git log.
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"""
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Functions for computation of centroids.
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"""
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from typing import Tuple, Any
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from collections.abc import Collection
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class PointsCentroid:
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""" Centroid computation from single points using an online algorithm.
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More points may be added at any time.
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Coordinates are internally treated as a 7-digit fixed-point float
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(i.e. in OSM style).
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"""
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def __init__(self) -> None:
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self.sum_x = 0
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self.sum_y = 0
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self.count = 0
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def centroid(self) -> Tuple[float, float]:
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""" Return the centroid of all points collected so far.
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"""
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if self.count == 0:
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raise ValueError("No points available for centroid.")
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return (self.sum_x / self.count / 10_000_000,
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self.sum_y / self.count / 10_000_000)
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def __len__(self) -> int:
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return self.count
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def __iadd__(self, other: Any) -> 'PointsCentroid':
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if isinstance(other, Collection) and len(other) == 2:
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if all(isinstance(p, (float, int)) for p in other):
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x, y = other
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self.sum_x += int(x * 10_000_000)
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self.sum_y += int(y * 10_000_000)
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self.count += 1
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return self
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raise ValueError("Can only add 2-element tuples to centroid.")
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