spacepy.coordinates.Coords¶
- class spacepy.coordinates.Coords(data, dtype, carsph[, units, ticks, use_irbem])[source]¶
A class holding spatial coordinates and enabling transformation between coordinate systems. Coordinates can be stored as Cartesian or spherical and units are assumed to be Re (distance) and degrees (angle)
Note
Although other units may be specified and will be carried through, most functions throughout SpacePy assume distances in Re and angles in degrees, regardless of specified units.
By default, coordinate transforms are based on the IRBEM library; its manual may prove useful. SpacePy also provides a framework for accurate coordinate transformations. This can be used by setting the use_irbem flag to False. In a future release of SpacePy this will become the default method. For a good reference on heliospheric and magnetospheric coordinate systems, see Franz & Harper, “Heliospheric Coordinate Systems”, Planet. Space Sci., 50, pp 217-233, 2002 (https://doi.org/10.1016/S0032-0633(01)00119-2).
- Parameters
- datalist or ndarray, dim = (n,3)
coordinate points [X,Y,Z] or [rad, lat, lon]
- dtypestring
coordinate system; supported systems are defined in module-level documentation. Common systems include GEO, GSE, GSM, SM, MAG, ECIMOD
- carsphstring
Cartesian or spherical, ‘car’ or ‘sph’
- unitslist of strings, optional
standard are [‘Re’, ‘Re’, ‘Re’] or [‘Re’, ‘deg’, ‘deg’] depending on the carsph content. See note.
- ticksTicktock instance, optional
used for coordinate transformations (see a.convert)
- use_irbembool
New in version 0.3.0.
Set to True to use IRBEM for coordinate transforms (current default). Otherwise use SpacePy’s coordinate transform library.
- Returns
- outCoords instance
instance with a.data, a.carsph, etc.
See also
spacepy.coordinates.DEFAULTS
spacepy.time.Ticktock
Examples
>>> from spacepy import coordinates as coord >>> cvals = coord.Coords([[1,2,4],[1,2,2]], 'GEO', 'car') >>> cvals.x # returns all x coordinates array([1, 1]) >>> from spacepy.time import Ticktock >>> cvals.ticks = Ticktock(['2002-02-02T12:00:00', '2002-02-02T12:00:00'], 'ISO') # add ticks >>> newcoord = cvals.convert('GSM', 'sph') >>> newcoord
append
(other)Append another Coords instance to the current one
convert
(returntype, returncarsph)Create a new Coords instance with new coordinate types
from_skycoord
(skycoord[, use_irbem])Create a Coords instance from an Astropy SkyCoord instance
- append(other)[source]¶
Append another Coords instance to the current one
- Parameters
- otherCoords instance
Coords instance to append
- convert(returntype, returncarsph)[source]¶
Create a new Coords instance with new coordinate types
- Parameters
- returntypestring
coordinate system, see module level documentation for supported systems
- returncarsphstring
coordinate type, possible ‘car’ for Cartesian and ‘sph’ for spherical
- Returns
- outCoords object
Coords object in the new coordinate system
Examples
>>> from spacepy.coordinates import Coords >>> y = Coords([[1,2,4],[1,2,2]], 'GEO', 'car') >>> from spacepy.time import Ticktock >>> y.ticks = Ticktock(['2002-02-02T12:00:00', '2002-02-02T12:00:00'], 'ISO') >>> x = y.convert('SM','car') >>> x Coords( [[ 0.81134097 2.6493305 3.6500375 ] [ 0.92060408 2.30678864 1.68262126]] ), dtype=SM,car, units=['Re', 'Re', 'Re']
- classmethod from_skycoord(skycoord, use_irbem=None)[source]¶
Create a Coords instance from an Astropy SkyCoord instance
- Parameters
- skycoordastropy.coordinates.SkyCoord
The coordinate to be converted
- Returns
- outCoords instance
The converted coordinate
Notes
This method requires Astropy to be installed.
This method uses the GEO coordinate frame as the common frame between the two libraries.
- to_skycoord()[source]¶
Create an Astropy SkyCoord instance based on this instance
- Returns
- outastropy.coordinates.SkyCoord
This coordinate as an Astropy SkyCoord
Notes
This method requires Astropy to be installed.
This method uses the GEO coordinate frame as the common frame between the two libraries.