Setting Parameters and Invoking Tasks

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1.4.5 Setting Parameters and Invoking Tasks

Inside the Toolkit:

In the current version of CASA, you cannot use the task parameter setting features, such as the inp, default, or go commands, for the tools.

One can set parameters for tasks (but not for tools) by performing the assignment within the CASA shell and then inspecting them using the inp command:

CASA <30>: default(bandpass)
CASA <31>: vis = ’ngc5921.demo.ms’
CASA <32>: caltable = ’ngc5921.demo.bcal’
CASA <33>: field = ’0’
CASA <34>: refant = ’15’
CASA <35>: inp(’bandpass’)
#  bandpass :: Calculates a bandpass calibration solution
vis         = ’ngc5921.demo.ms’ #  Nome of input visibility file
caltable    = ’ngc5921.demo.bcal’ #  Name of output gain calibration table
field       =        ’0’        #  Select field using field id(s) or field name(s)
spw         =         ’’        #  Select spectral window/channels
selectdata  =      False        #  Other data selection parameters
solint      =      ’inf’        #  Solution interval
combine     =     ’scan’        #  Data axes which to combine for solve (scan, spw, field)
refant      =       ’15’        #  Reference antenna name
minblperant =          4        #  Minimum baselines _per antenna_ required for solve
solnorm     =      False        #  Normalize average solution amplitudes to 1.0 (G, T only)
bandtype    =        ’B’        #  Type of bandpass solution (B or BPOLY)
  fillgaps  =          0        #  Fill flagged solution channels by interpolation
append      =      False        #  Append solutions to the (existing) table
gaintable   =         ’’        #  Gain calibration table(s) to apply on the fly
gainfield   =         ’’        #  Select a subset of calibrators from gaintable(s)
interp      =         ’’        #  Interpolation mode (in time) to use for each gaintable
spwmap      =         []        #  Spectral windows combinations to form for gaintables(s)
gaincurve   =      False        #  Apply internal VLA antenna gain curve correction
opacity     =        0.0        #  Opacity correction to apply (nepers)
parang      =      False        #  Apply parallactic angle correction
async       =      False        #

See § 1.4.5.4 below for more details on the use of the inputs command.

All task parameters have global scope within CASA: the parameter values are common to all tasks and also at the CASA command line. This allows the convenience of not changing parameters that are shared between tasks but does require care when chaining together sequences of task invocations (to ensure proper values are provided).

If you want to reset the input keywords for a single task, use the default command (§ 1.4.5.2). For example, to set the defaults for the bandpass task, type:

CASA <30>: default(’bandpass’)

as we did above.

To inspect a single parameter value just type it at the command line. Continuing the above example:

CASA <36>: combine
Out[14]: ’scan’

CASA parameters are just Python variables.

Parameters for a given task can be saved by using the saveinputs command (see § 1.4.5.5) and restored using the execfile ’<filename>’ command. Note that if the task is successfully executed, then a <taskname>.last file is created in the working directory containing the parameter values (see § 1.4.5.8).

We now describe the individual CASA task parameter interface commands and features in more detail.

   1.4.5.1 The scope of parameters in CASA
   1.4.5.2 The default Command
   1.4.5.3 The go Command
   1.4.5.4 The inp Command
   1.4.5.5 The saveinputs Command
   1.4.5.6 The tget Command
   1.4.5.7 The tput Command
   1.4.5.8 The .last file

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