Geod¶
pyproj.Geod¶
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class
pyproj.Geod(initstring=None, **kwargs)[source]¶ Bases:
pyproj._geod.Geodperforms forward and inverse geodetic, or Great Circle, computations. The forward computation (using the ‘fwd’ method) involves determining latitude, longitude and back azimuth of a computations. The forward computation (using the ‘fwd’ method) involves determining latitude, longitude and back azimuth of a terminus point given the latitude and longitude of an initial point, plus azimuth and distance. The inverse computation (using the ‘inv’ method) involves determining the forward and back azimuths and distance given the latitudes and longitudes of an initial and terminus point.
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__init__(initstring=None, **kwargs)[source]¶ initialize a Geod class instance.
Geodetic parameters for specifying the ellipsoid can be given in a dictionary ‘initparams’, as keyword arguments, or as as proj4 geod initialization string. Following is a list of the ellipsoids that may be defined using the ‘ellps’ keyword (these are stored in the model variable pj_ellps):
MERIT a=6378137.0 rf=298.257 MERIT 1983 SGS85 a=6378136.0 rf=298.257 Soviet Geodetic System 85 GRS80 a=6378137.0 rf=298.257222101 GRS 1980(IUGG, 1980) IAU76 a=6378140.0 rf=298.257 IAU 1976 airy a=6377563.396 b=6356256.910 Airy 1830 APL4.9 a=6378137.0. rf=298.25 Appl. Physics. 1965 airy a=6377563.396 b=6356256.910 Airy 1830 APL4.9 a=6378137.0. rf=298.25 Appl. Physics. 1965 NWL9D a=6378145.0. rf=298.25 Naval Weapons Lab., 1965 mod_airy a=6377340.189 b=6356034.446 Modified Airy andrae a=6377104.43 rf=300.0 Andrae 1876 (Den., Iclnd.) aust_SA a=6378160.0 rf=298.25 Australian Natl & S. Amer. 1969 GRS67 a=6378160.0 rf=298.247167427 GRS 67(IUGG 1967) bessel a=6377397.155 rf=299.1528128 Bessel 1841 bess_nam a=6377483.865 rf=299.1528128 Bessel 1841 (Namibia) clrk66 a=6378206.4 b=6356583.8 Clarke 1866 clrk80 a=6378249.145 rf=293.4663 Clarke 1880 mod. CPM a=6375738.7 rf=334.29 Comm. des Poids et Mesures 1799 delmbr a=6376428. rf=311.5 Delambre 1810 (Belgium) engelis a=6378136.05 rf=298.2566 Engelis 1985 evrst30 a=6377276.345 rf=300.8017 Everest 1830 evrst48 a=6377304.063 rf=300.8017 Everest 1948 evrst56 a=6377301.243 rf=300.8017 Everest 1956 evrst69 a=6377295.664 rf=300.8017 Everest 1969 evrstSS a=6377298.556 rf=300.8017 Everest (Sabah & Sarawak) fschr60 a=6378166. rf=298.3 Fischer (Mercury Datum) 1960 fschr60m a=6378155. rf=298.3 Modified Fischer 1960 fschr68 a=6378150. rf=298.3 Fischer 1968 helmert a=6378200. rf=298.3 Helmert 1906 hough a=6378270.0 rf=297. Hough helmert a=6378200. rf=298.3 Helmert 1906 hough a=6378270.0 rf=297. Hough intl a=6378388.0 rf=297. International 1909 (Hayford) krass a=6378245.0 rf=298.3 Krassovsky, 1942 kaula a=6378163. rf=298.24 Kaula 1961 lerch a=6378139. rf=298.257 Lerch 1979 mprts a=6397300. rf=191. Maupertius 1738 new_intl a=6378157.5 b=6356772.2 New International 1967 plessis a=6376523. b=6355863. Plessis 1817 (France) SEasia a=6378155.0 b=6356773.3205 Southeast Asia walbeck a=6376896.0 b=6355834.8467 Walbeck WGS60 a=6378165.0 rf=298.3 WGS 60 WGS66 a=6378145.0 rf=298.25 WGS 66 WGS72 a=6378135.0 rf=298.26 WGS 72 WGS84 a=6378137.0 rf=298.257223563 WGS 84 sphere a=6370997.0 b=6370997.0 Normal Sphere (r=6370997)
The parameters of the ellipsoid may also be set directly using the ‘a’ (semi-major or equatorial axis radius) keyword, and any one of the following keywords: ‘b’ (semi-minor, or polar axis radius), ‘e’ (eccentricity), ‘es’ (eccentricity squared), ‘f’ (flattening), or ‘rf’ (reciprocal flattening).
See the proj documentation (https://github.com/OSGeo/proj.4/wiki) for more information about specifying ellipsoid parameters (specifically, the chapter ‘Specifying the Earth’s figure’ in the main Proj users manual).
Example usage:
>>> from pyproj import Geod >>> g = Geod(ellps='clrk66') # Use Clarke 1866 ellipsoid. >>> # specify the lat/lons of some cities. >>> boston_lat = 42.+(15./60.); boston_lon = -71.-(7./60.) >>> portland_lat = 45.+(31./60.); portland_lon = -123.-(41./60.) >>> newyork_lat = 40.+(47./60.); newyork_lon = -73.-(58./60.) >>> london_lat = 51.+(32./60.); london_lon = -(5./60.) >>> # compute forward and back azimuths, plus distance >>> # between Boston and Portland. >>> az12,az21,dist = g.inv(boston_lon,boston_lat,portland_lon,portland_lat) >>> "%7.3f %6.3f %12.3f" % (az12,az21,dist) '-66.531 75.654 4164192.708' >>> # compute latitude, longitude and back azimuth of Portland, >>> # given Boston lat/lon, forward azimuth and distance to Portland. >>> endlon, endlat, backaz = g.fwd(boston_lon, boston_lat, az12, dist) >>> "%6.3f %6.3f %13.3f" % (endlat,endlon,backaz) '45.517 -123.683 75.654' >>> # compute the azimuths, distances from New York to several >>> # cities (pass a list) >>> lons1 = 3*[newyork_lon]; lats1 = 3*[newyork_lat] >>> lons2 = [boston_lon, portland_lon, london_lon] >>> lats2 = [boston_lat, portland_lat, london_lat] >>> az12,az21,dist = g.inv(lons1,lats1,lons2,lats2) >>> for faz,baz,d in list(zip(az12,az21,dist)): "%7.3f %7.3f %9.3f" % (faz,baz,d) ' 54.663 -123.448 288303.720' '-65.463 79.342 4013037.318' ' 51.254 -71.576 5579916.651' >>> g2 = Geod('+ellps=clrk66') # use proj4 style initialization string >>> az12,az21,dist = g2.inv(boston_lon,boston_lat,portland_lon,portland_lat) >>> "%7.3f %6.3f %12.3f" % (az12,az21,dist) '-66.531 75.654 4164192.708'
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fwd(lons, lats, az, dist, radians=False)[source]¶ forward transformation - Returns longitudes, latitudes and back azimuths of terminus points given longitudes (lons) and latitudes (lats) of initial points, plus forward azimuths (az) and distances (dist). latitudes (lats) of initial points, plus forward azimuths (az) and distances (dist).
Works with numpy and regular python array objects, python sequences and scalars.
if radians=True, lons/lats and azimuths are radians instead of degrees. Distances are in meters.
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inv(lons1, lats1, lons2, lats2, radians=False)[source]¶ inverse transformation - Returns forward and back azimuths, plus distances between initial points (specified by lons1, lats1) and terminus points (specified by lons2, lats2).
Works with numpy and regular python array objects, python sequences and scalars.
if radians=True, lons/lats and azimuths are radians instead of degrees. Distances are in meters.
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npts(lon1, lat1, lon2, lat2, npts, radians=False)[source]¶ Given a single initial point and terminus point (specified by python floats lon1,lat1 and lon2,lat2), returns a list of longitude/latitude pairs describing npts equally spaced intermediate points along the geodesic between the initial and terminus points.
if radians=True, lons/lats are radians instead of degrees.
Example usage:
>>> from pyproj import Geod >>> g = Geod(ellps='clrk66') # Use Clarke 1866 ellipsoid. >>> # specify the lat/lons of Boston and Portland. >>> boston_lat = 42.+(15./60.); boston_lon = -71.-(7./60.) >>> portland_lat = 45.+(31./60.); portland_lon = -123.-(41./60.) >>> # find ten equally spaced points between Boston and Portland. >>> lonlats = g.npts(boston_lon,boston_lat,portland_lon,portland_lat,10) >>> for lon,lat in lonlats: '%6.3f %7.3f' % (lat, lon) '43.528 -75.414' '44.637 -79.883' '45.565 -84.512' '46.299 -89.279' '46.830 -94.156' '47.149 -99.112' '47.251 -104.106' '47.136 -109.100' '46.805 -114.051' '46.262 -118.924' >>> # test with radians=True (inputs/outputs in radians, not degrees) >>> import math >>> dg2rad = math.radians(1.) >>> rad2dg = math.degrees(1.) >>> lonlats = g.npts(dg2rad*boston_lon,dg2rad*boston_lat,dg2rad*portland_lon,dg2rad*portland_lat,10,radians=True) >>> for lon,lat in lonlats: '%6.3f %7.3f' % (rad2dg*lat, rad2dg*lon) '43.528 -75.414' '44.637 -79.883' '45.565 -84.512' '46.299 -89.279' '46.830 -94.156' '47.149 -99.112' '47.251 -104.106' '47.136 -109.100' '46.805 -114.051' '46.262 -118.924'
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