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119 lines
4.1 KiB
119 lines
4.1 KiB
# igc2kmz coordinate functions |
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# Copyright (C) 2008 Tom Payne |
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# |
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# This program is free software: you can redistribute it and/or modify |
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# it under the terms of the GNU General Public License as published by |
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# the Free Software Foundation, either version 3 of the License, or |
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# (at your option) any later version. |
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# |
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# This program is distributed in the hope that it will be useful, |
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# but WITHOUT ANY WARRANTY; without even the implied warranty of |
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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# GNU General Public License for more details. |
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# |
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# You should have received a copy of the GNU General Public License |
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# along with this program. If not, see <http://www.gnu.org/licenses/>. |
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from math import acos, asin, atan2, cos, pi, sin, sqrt |
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R = 6371000.0 |
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cardinals = 'N NNE NE ENE E ESE SE SSE S SSW SW WSW W WNW NW NNW'.split() |
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def rad_to_cardinal(rad): |
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while rad < 0.0: |
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rad += 2 * pi |
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return cardinals[int(8 * rad / pi + 0.5) % 16] |
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class degreeattr(object): |
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def __init__(self, attr): |
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self.attr = attr |
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def __get__(self, obj, type=None): |
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return 180.0 * getattr(obj, self.attr) / pi |
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def __set__(self, obj, value): |
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setattr(obj, self.attr, pi * value / 180.0) |
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class degreemethod(object): |
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def __new__(cls, f): |
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def deg_f(*args, **kwargs): |
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return 180.0 * f(*args, **kwargs) / pi |
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return deg_f |
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class Coord(object): |
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__slots__ = ('lat', 'lon', 'ele', 'dt') |
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lat_deg = degreeattr('lat') |
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lon_deg = degreeattr('lon') |
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def __init__(self, lat, lon, ele, dt=None): |
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self.lat = lat |
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self.lon = lon |
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self.ele = ele |
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self.dt = dt |
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@classmethod |
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def deg(cls, lat, lon, ele, dt=None): |
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return cls(pi * lat / 180.0, pi * lon / 180.0, ele, dt) |
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def dup(self): |
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return Coord(self.lat, self.lon, self.ele, self.dt) |
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def initial_bearing_to(self, other): |
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"""Return the initial bearing from self to other.""" |
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y = sin(other.lon - self.lon) * cos(other.lat) |
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x = cos(self.lat) * sin(other.lat) \ |
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- sin(self.lat) * cos(other.lat) * cos(other.lon - self.lon) |
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return atan2(y, x) |
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initial_bearing_to_deg = degreemethod(initial_bearing_to) |
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def distance_to(self, other): |
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"""Return the distance from self to other.""" |
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d = sin(self.lat) * sin(other.lat) \ |
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+ cos(self.lat) * cos(other.lat) * cos(self.lon - other.lon) |
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return R * acos(d) if d < 1.0 else 0.0 |
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def halfway_to(self, other): |
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"""Return the point halfway between self and other.""" |
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bx = cos(other.lat) * cos(other.lon - self.lon) |
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by = cos(other.lat) * sin(other.lon - self.lon) |
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cos_lat_plus_bx = cos(self.lat) + bx |
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lat = atan2(sin(self.lat) + sin(other.lat), |
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sqrt(cos_lat_plus_bx * cos_lat_plus_bx + by * by)) |
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lon = self.lon + atan2(by, cos_lat_plus_bx) |
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ele = (self.ele + other.ele) / 2.0 |
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return Coord(lat, lon, ele) |
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def interpolate(self, other, delta): |
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"""Return the point delta between self and other.""" |
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d = sin(self.lat) * sin(other.lat) \ |
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+ cos(self.lat) * cos(other.lat) * cos(other.lon - self.lon) |
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d = delta * acos(d) if d < 1.0 else 0.0 |
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y = sin(other.lon - self.lon) * cos(other.lat) |
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x = cos(self.lat) * sin(other.lat) \ |
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- sin(self.lat) * cos(other.lat) * cos(other.lon - self.lon) |
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theta = atan2(y, x) |
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lat = asin(sin(self.lat) * cos(d) + cos(self.lat) * sin(d) * cos(theta)) |
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lon = self.lon + atan2(sin(theta) * sin(d) * cos(self.lat), |
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cos(d) - sin(self.lat) * sin(lat)) |
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ele = (1.0 - delta) * self.ele + delta * other.ele |
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return Coord(lat, lon, ele) |
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def coord_at(self, theta, d): |
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"""Return the point d from self in direction theta.""" |
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lat = asin(sin(self.lat) * cos(d / R) |
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+ cos(self.lat) * sin(d / R) * cos(theta)) |
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lon = self.lon + atan2(sin(theta) * sin(d / R) * cos(self.lat), |
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cos(d / R) - sin(self.lat) * sin(lat)) |
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ele = self.ele |
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return Coord(lat, lon, ele)
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