pyarts.workspace¶

The workspace subpackage provides an interactive interface to ARTS and can be used to directly call workspace methods and agendas as well as access and manipulate workspace variables.

Setup¶

The python interface needs access to the libarts_api.so shared library, which is located in the src subfolder of the ARTS build tree. The interface expects the location of the ARTS build tree to be provided in the ARTS_BUILD_PATH environment variable. For the libarts_api.so to be built, ARTS needs to be configured with -DENABLE_C_API=1:

cmake -DENABLE_C_API=1 ... /path/to/arts

The Workspace Class¶

The main functionality of the interface is implemented by the Workspace class. A Workspace object represents an ongoing ARTS simulation and is used to execute controlfiles and workspace methods and access workspace variables

>>> from arts.workspace import Workspace
>>> ws = Workspace()

Executing Controlfiles¶

Controlfiles can be executed on a workspace using the execute_controlfile() method.

>>> ws.execute_controlfile("general.arts")

The search path for controlfiles is the current directory plus the paths provided in the environment variable ARTS_INCLUDE_PATH. Controlfiles are parsed only once and then cached. Thus, if a controlfile is modified after it has been loaded, these changes will only be effective after a restart of the python runtime.

Calling Workspace Methods¶

ARTS workspace methods are available as member functions of each Workspace object:

>>> ws.AtmosphereSet1D()
>>> ws.IndexSet(ws.stokes_dim, 1)

Arguments can be passed to a workspace function in three ways:

As workspace variables using the attributes of the workspace object, such as ws.stokes_dim in the example above.

Using one of the symbolic variables in arts.workspace.variables

Passing supported python objects directly

Arguments to a WSM can be passed using either positional or named arguments or both. If positional arguments are provided at least all generic output and generic input arguments must be given in order.

>>> ws.VectorNLogSpace(ws.p_grid, 361, 500e2, 0.1 )

Keyword arguments to define generic input and output arguments. Available keywords are the names of the generic outputs and inputs defined in methods.cc.

>>> ws.abs_speciesSet(species=[ "O3" ])

Calls to supergeneric functions are resolved by the interface.

Workspace Variables¶

Symbolic representation of all workspace variables are available in the arts.workspace.variables module as module attributes. The purpose of these is to be passed to workspace functions as placeholders for variables in the workspace.

Variable objects can be associated to a workspace, which is the case for variables accessed as attributes of a workspace, i.e. using for example:

>>> ws.y

If that is the case their value can be accessed using the value() member function. In order to print out a textual representation of the value, the print() member function can be used, which will call the corresponding Print() ARTS WSV.

Workspace variables of the groups Vector, Matrix and Tensor with an associated workspace implement the numpy array interface and can therefore be used just as any other numpy array. In some cases, however, it may be necessary to explicitly create a view on the array using numpy.asarray.

`arts_agenda`(func)	Parse python method as ARTS agenda
`Include`(agenda)	Simple helper class to handle INCLUDE statements in agenda definitions.
`Workspace`([verbosity, agenda_verbosity])	The Workspace class represents an ongoing ARTS simulation.