34 lines
1.2 KiB
Python
34 lines
1.2 KiB
Python
# -*- coding: utf-8 -*-
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import math
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EARTH_RADIUS_KM = 6373
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def haversine_distance(lat1, lon1, lat2, lon2, radius=EARTH_RADIUS_KM):
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"""Calculate the Haversine distance between two lat/lon pairs, given by:
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a = sin²(Δφ/2) + cos φ1 ⋅ cos φ2 ⋅ sin²(Δλ/2)
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c = 2 ⋅ atan2( √a, √(1−a) )
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d = R ⋅ c
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where R is the radius of the Earth (in kilometers). By default we use 6373 km,
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a radius optimized for calculating distances at approximately 39 degrees from
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the equator i.e. Washington, DC
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:param lat1: first latitude
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:param lon1: first longitude (use negative range for longitudes West of the Prime Meridian)
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:param lat2: second latitude
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:param lon2: second longitude (use negative range for longitudes West of the Prime Meridian)
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:param radius: radius of the Earth in (miles|kilometers) depending on the desired units
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"""
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lat1 = math.radians(lat1)
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lat2 = math.radians(lat2)
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lon1 = math.radians(lon1)
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lon2 = math.radians(lon2)
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dlon = lon2 - lon1
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dlat = lat2 - lat1
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a = (math.sin(dlat / 2.0)) ** 2 + math.cos(lat1) * math.cos(lat2) * (math.sin(dlon/2.0)) ** 2
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c = 2 * math.atan2(math.sqrt(a), math.sqrt(1 - a))
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d = radius * c
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return d
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