38 lines
1.1 KiB
Python
38 lines
1.1 KiB
Python
from math import sin, cos, asin, sqrt, radians
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earth_flatening = 1.0/298.257223563
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earth_radius = 6378137.0
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def haversine(lat1, lon1, lat2, lon2):
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"""
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Calculate the great circle distance between two points
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on the earth (specified in decimal degrees)
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"""
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# convert decimal degrees to radians
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lon1, lat1, lon2, lat2 = map(radians, [lon1, lat1, lon2, lat2])
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# haversine formula
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dlon = lon2 - lon1
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dlat = lat2 - lat1
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a = sin(dlat/2)**2 + cos(lat1) * cos(lat2) * sin(dlon/2)**2
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c = 2 * asin(sqrt(a))
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# 6367 km is the radius of the Earth
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return earth_radius * c
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def roydistance(lat1, lon1, lat2, lon2):
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"""
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Calculate the great circle distance between two points
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on the earth (specified in decimal degrees)
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"""
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# convert decimal degrees to radians
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lon1, lat1, lon2, lat2 = map(radians, [lon1, lat1, lon2, lat2])
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# Roy's method
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f1 = (1.0 - earth_flatening)
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top = (pow((lon2-lon1), 2) * pow(cos(lat1), 2)) + pow(lat2-lat1, 2)
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bot = pow(sin(lat1), 2) + (pow(f1, 2) * pow(cos(lat1), 2))
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return f1 * earth_radius * sqrt(top/bot)
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