tkp.accessors – Image container classes

Introduction

The “accessors” system attempts to abstract away the physical image storage format from the library logic. The higher-level data access routines should not care whether the data is stored in a CASA table, or a FITS file, or in some other format: they should be coded against a uniform interface provided by the appropriate accessor.

An accessor should subclass tkp.accessors.dataaccessor.DataAccessor, which is an abstract base class. Accessors must conform to the DataAccessor interface by defining the relevant attributes (see the attributes listed under tkp.accessors.dataaccessor.DataAccessor for full details). An accessor which provides all of these attributes is guaranteed to be usable with all core TraP functionality.

In some cases, most notably quality control, specialized (eg, per-telescope) metadata may also be required. A further abstract base class should be constructed to define the interface required. For example, tkp.accessors.lofaraccessor.LofarAccessor defines the following metadata which must be provided for LOFAR quality control:

antenna_set
Antenna set in use during observation. String; LBA_INNER, LBA_OUTER, LBA_SPARSE, LBA or HBA
ncore
Number of core stations in use during observations constituting this image. Integer.
nremote
Number of remote stations in use during observations constituting this image. Integer.
nintl
Number of international stations in use during observations constituting this image. Integer.
subbandwidth
Width of a subband, in Hz.
subbands
Number of subbands.