sourcefinder.accessors.casaimage
================================

.. py:module:: sourcefinder.accessors.casaimage


Attributes
----------

.. autoapisummary::

   sourcefinder.accessors.casaimage.logger


Classes
-------

.. autoapisummary::

   sourcefinder.accessors.casaimage.CasaImage


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

.. py:class:: CasaImage(url, plane=0, beam=None)

   Bases: :py:obj:`sourcefinder.accessors.dataaccessor.DataAccessor`


   
   Provides common functionality for pulling data from the CASA image format.

   (Technically known as the 'MeasurementSet' format.)

   :Parameters:

       **url** : str
           The location of the CASA image file.

       **plane** : int, default: 0
           The data plane to extract from the image cube.

       **beam** : tuple, default: None
           Beam parameters (major axis, minor axis, position angle) in degrees.
           If not provided, these are extracted from the CASA table.











   .. rubric:: Notes

   CasaImage does not provide tau_time or taustart_ts, as there was
   no clear standard for these metadata, so cannot be
   instantiated directly - subclass it and extract these attributes
   as appropriate to a given telescope.



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   .. py:method:: parse_beam(table)

      
      Extract beam parameters from the CASA table.


      :Parameters:

          **table** : casacore.tables.table
              The CASA table from which the beam parameters are extracted.



      :Returns:

          **bmaj** : float
              The semi-major axis of the beam in degrees.

          **bmin** : float
              The semi-minor axis of the beam in degrees.

          **bpa** : float
              The angle of the major axis of the synthesized beam,
              measured east from local north, in degrees.











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   .. py:method:: parse_coordinates(table)

      
      Parse and return a WCS (World Coordinate System) object from the
      CASA table.


      :Parameters:

          **table** : casacore.tables.table
              The CASA table from which the WCS information is extracted.



      :Returns:

          **wcs** : WCS
              A WCS object containing the coordinate system information extracted
              from the CASA table.











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   .. py:method:: parse_data(table, plane=0)

      
      Extract and squeeze data from a CASA table, select desired plane and
      transpose.
      Squeezing is done to remove any singleton dimensions.


      :Parameters:

          **table** : casacore.tables.table
              The CASA table from which data is extracted.

          **plane** : int, default: 0
              The data plane to extract from the image cube.



      :Returns:

          **data** : numpy.ndarray
              The extracted and transposed data array. If the data cube has more
              than two dimensions - after removing singleton dimensions - the
              plane specified by the `plane` parameter is selected from the first
              axis.











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   .. py:method:: parse_frequency(table)

      
      Extract frequency-related information from the CASA table headers.


      :Parameters:

          **table** : casacore.tables.table
              The CASA table from which frequency information is extracted.



      :Returns:

          **freq_eff** : float
              The effective frequency (rest frequency) in Hz.

          **freq_bw** : float
              The frequency bandwidth (channel width) in Hz.











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   .. py:method:: parse_phase_centre(table)
      :staticmethod:


      
      Assume the units for the pointing centre are in radians and return the
      RA modulo 360.


      :Parameters:

          **table** : casacore.tables.table
              The CASA table from which the pointing centre is extracted.











      .. rubric:: Notes

      The units for the pointing centre are not given in either the image
      cube itself nor in the image content description. Assume radians. The
      Right Ascension (RA) is returned modulo 360 to ensure it is always
      within the range 0 <= RA < 360.



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   .. py:method:: parse_taustartts(table)
      :staticmethod:


      
      Extract integration start-time from CASA table header.

      This applies to some CASA images (typically those created from uvFITS
      files) but not all, and so should be called for each sub-class.

      :Parameters:

          **table** : casacore.tables.table
              The MAIN table of the CASA image.



      :Returns:

          datetime.datetime
              Time of observation start as an instance of `datetime.datetime`.











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   .. py:method:: unique_column_values(table, column_name)
      :staticmethod:


      
      Find all the unique values in a particular column of a CASA table.


      :Parameters:

          **table** : casacore.tables.table
              The CASA table from which the column values are extracted.

          **column_name** : str
              The name of the column to extract unique values from.



      :Returns:

          numpy.ndarray
              An array containing the unique values in the specified column.











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   .. py:attribute:: data


   .. py:attribute:: pixelsize


   .. py:attribute:: url


   .. py:attribute:: wcs


.. py:data:: logger