Difference between revisions of "Vishead"

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== Help on vishead task: ==
+
{{vishead}}
 
 
<pre>
 
List, summary, get, and put metadata in a measurement set
 
 
 
        This task allows the user to manipulate some meta-data parameters in a
 
        measurement set.  The mode='list' shows those keywords that are
 
        presently implemented, with their values.  The contents associated
 
        with the keywords can be obtained (get) and changed (put).
 
 
 
        The modes that are available are:
 
 
 
          list    --- List all keywords that are recognized, and list the
 
                      value(s) for each.  Only these keywords can be obtained
 
                      (get) or changed (put)
 
          summary --- Equivalent to running taskname='listobs'; verbose=F
 
          get    --- Get the specified keyword value(s) from the ms
 
          put    --- Put the specified keyword value(s) into the ms
 
 
 
        Parameters currently implemented are (June 1, 2009):
 
 
 
          cal_grp             
 
          field                Field names
 
          fld_code              Field Observing codes
 
          freq_group_name     
 
          log                 
 
          observer              Observer name
 
          project              Project name
 
          ptcs                  Phase tracking centers for each field
 
          release_date         
 
          schedule
 
          schedule_type
 
          spw_name              Spectral parameters?
 
          source_name          Source Names (=Field Names?)
 
          telescope            Telescope Name
 
 
 
        Keyword arguments:
 
 
 
        vis  --- Name of input visibility file
 
                  default: none, example: vis='my.ms'
 
 
 
        mode --- Mode of operation for vishead
 
                  default = 'list'; example: mode='get'
 
 
 
        hdkey--- keyword to get or put from the ms (used in get/put mode only)
 
                  ex: hdkey='telescope'
 
 
 
        hdindex--- index (counting from 0) if keyword is an array (used in get/put
 
                  mode only)
 
 
 
        hdkey--- keyword to get or put from the ms (used in get/put mode only)
 
                  ex: hdkey='telescope'
 
 
 
        hdindex--- index (counting from 0) if keyword is an array (used in get/put
 
                  mode only)
 
                  ex: hdindex='2'; hdindex=''->put/get full array;
 
 
 
        hdvalue  --- value to be put in the MS (used in put mode only)
 
                  ex: hdvalue=array(['MyTelescope'])
 
 
 
 
 
 
 
 
 
        Examples:
 
 
 
          To transfer the parameters to useful python items requires some care.
 
 
 
          taskname = 'vishead'
 
          default()
 
          vis = '3C84C.ms'
 
          mode = 'get'
 
                     
 
          to get a field name (string),
 
              hdkey = 'field'; hdindex = '2'; hdvalue=vishead();
 
                      print hdvalue[0] = the name for field='2'                   
 
               
 
          to get an phase center (number)
 
              hdkey = 'ptcs'; hdindex = '1'; hdvalue = vishead();
 
                      hdvalue[0][0] gives the ra, hdvalue[0][1] gives the dec in field '1'
 
 
 
 
 
          taskname = 'vishead'
 
          default()
 
          vis = '3C84C.ms'
 
          mode = 'put'
 
 
 
          To change a string,
 
 
 
              hdkey = 'field'; hdindex = '2'; hdvalue = 'junk'; vishead()
 
                  field='2' is renamed 'junk'
 
 
 
          To change a number, (egs. ra of field=1 to 0.5 radian)
 
              is too complicated to figure out!
 
</pre>
 

Latest revision as of 16:37, 18 May 2015