Home       Trees       Indices       Help   
Package pyproj :: Class Geod

Class Geod

source code

object --+    
         |    
_proj.Geod --+
             |
            Geod

performs 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.

Instance Methods
 
__eq__(self, other)
equality operator == for Geod objects		 source code
 
__repr__(self)
repr(x)		 source code
 
fwd(self, lons, lats, az, dist, radians=False)
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).		 source code
 
inv(self, lons1, lats1, lons2, lats2, radians=False)
inverse transformation - Returns forward and back azimuths, plus distances between initial points (specified by lons1, lats1) and terminus points (specified by lons2, lats2).		 source code
 
npts(self, lon1, lat1, lon2, lat2, npts, radians=False)
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.		 source code

Inherited from _proj.Geod: __reduce__

Inherited from object: __delattr__, __format__, __getattribute__, __hash__, __init__, __reduce_ex__, __setattr__, __sizeof__, __str__, __subclasshook__

Static Methods
a new object with type S, a subtype of T
__new__(cls, initstring=None, **kwargs)
initialize a Geod class instance.		 source code
Properties

Inherited from _proj.Geod: initstring

Inherited from object: __class__

Method Details

__eq__(self, other)
(Equality operator)

source code 

equality operator == for Geod objects

Example usage:

>>> from pyproj import Geod
>>> gclrk1 = Geod(ellps='clrk66') # Use Clarke 1866 ellipsoid.
>>> gclrk2 = Geod(a=6378206.4, b=6356583.8) # Define Clarke 1866 using parameters
>>> gclrk1 == gclrk2
True
>>> gwgs66 = Geod('+ellps=WGS66')  # WGS 66 ellipsoid, Proj.4 style
>>> gnwl9d = Geod('+ellps=NWL9D')  # Naval Weapons Lab., 1965 ellipsoid
>>> # these ellipsoids are the same
>>> gnwl9d == gwgs66
True
>>> gclrk1 != gnwl9d  # Clarke 1866 is unlike NWL9D
True

__new__(cls, initstring=None, **kwargs)
Static Method

source code 

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'
Returns: a new object with type S, a subtype of T
Overrides: object.__new__

__repr__(self)
(Representation operator)

source code 

repr(x)

Overrides: object.__repr__
(inherited documentation)

fwd(self, lons, lats, az, dist, radians=False)

source code 

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.

inv(self, lons1, lats1, lons2, lats2, radians=False)

source code 

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.

npts(self, lon1, lat1, lon2, lat2, npts, radians=False)

source code 

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'

   Home       Trees       Indices       Help   
Generated by Epydoc 3.0.1 on Wed Nov 13 18:49:17 2019 http://epydoc.sourceforge.net