sourcefinder.accessors.dataaccessor
===================================

.. py:module:: sourcefinder.accessors.dataaccessor


Attributes
----------

.. autoapisummary::

   sourcefinder.accessors.dataaccessor.logger


Classes
-------

.. autoapisummary::

   sourcefinder.accessors.dataaccessor.DataAccessor


Module Contents
---------------

.. py:class:: DataAccessor

   
   Base class for accessors used with
   :class:`sourcefinder.image.ImageData`.

   Data accessors provide a uniform way for the ImageData class (i.e.,
   generic image representation) to access the various ways in which
   images may be stored (FITS files, arrays in memory, potentially HDF5,
   etc.).

   This class cannot be instantiated directly, but should be subclassed
   and the abstract properties provided. Note that all abstract
   properties are required to provide a valid accessor.

   Additional properties may also be provided by subclasses. However,
   TraP components are required to degrade gracefully in the absence of
   these optional properties.


   :Attributes:

       **beam** : tuple
           Restoring beam. Tuple of three floats: semi-major axis (in pixels),
           semi-minor axis (pixels), and position angle (radians).

       **centre_ra** : float
           Right ascension at the central pixel of the image. Units of J2000
           decimal degrees.

       **centre_decl** : float
           Declination at the central pixel of the image. Units of J2000
           decimal degrees.

       **data** : numpy.ndarray
           Two-dimensional numpy.ndarray of floating point pixel values.

       **freq_bw** : float
           The frequency bandwidth of this image in Hz.

       **freq_eff** : float
           Effective frequency of the image in Hz. That is, the mean frequency
           of all the visibility data which comprises this image.

       **pixelsize** : tuple
           (x, y) tuple representing the size of a pixel along each axis in
           units of degrees.

       **tau_time** : float
           Total time on sky in seconds.

       **taustart_ts** : float
           Timestamp of the first integration which constitutes part of this
           image. MJD in seconds.

       **url** : str
           A URL representing the location of the image at the time of
           processing.

       **wcs** : :class:`sourcefinder.utility.coordinates.WCS`
           An instance of :py:class:`sourcefinder.utility.coordinates.WCS`,
           describing the mapping from data pixels to sky-coordinates.










   .. rubric:: Notes

   The class also provides some common functionality: static methods used
   for parsing data files, and an 'extract_metadata' function which
   provides key info in a simple dict format.



   ..
       !! processed by numpydoc !!

   .. py:method:: degrees2pixels(bmaj, bmin, bpa, deltax, deltay) -> tuple[float, float, float]
      :staticmethod:


      
      Convert beam in degrees to beam in pixels and radians.
      For example, FITS beam parameters are in degrees.


      :Parameters:

          **bmaj** : float
              Beam major axis in degrees.

          **bmin** : float
              Beam minor axis in degrees.

          **bpa** : float
              Beam position angle in degrees.

          **deltax** : float
              Pixel size along the x-axis in degrees.

          **deltay** : float
              Pixel size along the y-axis in degrees.



      :Returns:

          **semimaj** : float
              Beam semi-major axis in pixels.

          **semimin** : float
              Beam semi-minor axis in pixels.

          **theta** : float
              Beam position angle in radians.











      ..
          !! processed by numpydoc !!


   .. py:method:: extract_metadata() -> dict

      
      Massage the class attributes into a flat dictionary with
      database-friendly values.

      While rather tedious, this is easy to serialize and store separately
      to the actual image data.

      May be extended by subclasses to return additional data.




      :Returns:

          dict
              A dictionary containing key-value pairs of class attributes
              formatted for database storage.











      ..
          !! processed by numpydoc !!


   .. py:method:: parse_pixelsize() -> tuple[float, float]

      
      Parse pixel size.





      :Returns:

          **deltax** : float
              Pixel size along the x axis in degrees.

          **deltay** : float
              Pixel size along the y axis in degrees.











      ..
          !! processed by numpydoc !!


   .. py:attribute:: beam
      :type:  Optional[tuple[float, float, float]]
      :value: None



   .. py:attribute:: centre_decl
      :type:  float


   .. py:attribute:: centre_ra
      :type:  float


   .. py:attribute:: conf
      :type:  Optional[sourcefinder.config.ImgConf]
      :value: None



   .. py:attribute:: data
      :type:  numpy.ndarray


   .. py:attribute:: freq_bw
      :type:  float


   .. py:attribute:: freq_eff
      :type:  float


   .. py:attribute:: pixelsize
      :type:  tuple


   .. py:attribute:: tau_time
      :type:  float


   .. py:attribute:: taustart_ts
      :type:  float


   .. py:attribute:: url
      :type:  str


   .. py:attribute:: wcs
      :type:  sourcefinder.utility.coordinates.WCS


.. py:data:: logger