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# stub function definition file for docstring parsing
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[docs]def virtualconcat(vis, concatvis='', freqtol='', dirtol='', respectname=True, visweightscale=[''], keepcopy=False, copypointing=True):
r"""
Concatenate several visibility data sets into a multi-MS
[`Description`_] [`Examples`_] [`Development`_] [`Details`_]
Parameters
- vis_ (stringArray) - List of names of input visibility files to be concatenated
- concatvis_ (string='') - Name of the output visibility file (a multi-MS)
- freqtol_ (variant='') - Frequency shift tolerance for considering data as the same spwid
- dirtol_ (variant='') - Direction shift tolerance for considering data as the same field
- respectname_ (bool=True) - If true, fields with a different name are not merged even if their direction agrees
- visweightscale_ (doubleArray=['']) - List of the weight scaling factors to be applied to the individual MSs
- keepcopy_ (bool=False) - If true, a copy of the input MSs is kept in their original place.
- copypointing_ (bool=True) - If true, keep the POINTING table information in the output MMS. If false, don\'t.
.. _Description:
Description
.. note:: **NOTE**: This task behaves mostly like the task **concat**,
except that the result is an MMS and that the original MSs
become part of the concatenated MS (unless you set
*keepcopy=True*).
The list of data sets given in the *vis* argument are moved into
an output Multi-MS data set and virtually concatenated. This task
will modify the input datasets by moving and reindexing them. If
you want to keep a copy of your original data, please set the
parameter *keepcopy* to True. It only makes sense to use
**virtualconcat** with *'keepcopy=True'*, instead of **concat**,
if you need to create an MMS instead of an MS.
There is no limit to the number of input data sets. If none of the
input data sets have any scratch columns (MODEL and CORRECTED
columns), none are created in the *concatvis* dataset. Otherwise
these columns are created on output and initialized to their
default value (1 in MODEL column, data in CORRECTED column) for
those data with no input columns.
Spectral windows for each data set with the same channelization,
and within a specified frequency tolerance of another data set,
will be combined into one spectral window. A field position in one
data set that is within a specified direction tolerance of another
field position in any other data set will be combined into
one field. The field names need not be the same (only their
position is used). Each appended dataset is assigned a new
observation ID if the corresponding rows in the observation table
are not the same.
.. rubric:: Parameter descriptions
*vis*
Name of input visibility files to be combined. No default
*concatvis*
Name of visibility file that will contain the concatenated data.
.. note:: **NOTE**: If this file exits on disk then the input files are
added to this file. Otherwise the new file contains the
concatenated data. Be careful here when concatenating to an
existing file.
No default.
*freqtol*
Frequency shift tolerance for considering data to be in the same
spw ID. The number of channels must also be the same. Default: '',
i.e., do not combine unless frequencies are equal. Example:
*freqtol='10MHz'* will not combine spw ID unless they are within
10 MHz.
.. note:: **NOTE**: This option is useful to combine spectral windows
with very slight frequency differences caused by Doppler
tracking, for example.
*dirtol*
Direction shift tolerance for considering data as the same field.
Default: '' means always combine. Example: *dirtol='1.arcsec'*
will not combine data for a field unless their phase center differ
by less than 1 arcsec. If the field names are different in the
input data sets, the name in the output data set will be the first
relevant data set in the list.
*respectname*
If True, fields with a different name are not merged even if their
direction agrees (within *dirtol*). Default: True
*visweightscale*
The weights of the individual MSs will be scaled in the
concatenated output MS by the factors in this list. Useful for
handling heterogeneous arrays. Use **plotms** to inspect the "Wt"
column as a reference for determining the scaling factors. See the
CASA Docs Chapter Pages on `Data
Weights <../../notebooks/data_weights.ipynb>`__
for more details. Example: *visweightscale=[1.,3.,3.]*, which
scales the weights of the second and third MS by a factor 3.
Default: [] (empty list) or no scaling
*keepcopy*
If True, a copy of the input MSs is kept in their original place.
Default: False
*copypointing*
If True, the POINTING table information will be present in the
output. If False, the result is an empty POINTING table. Default:
True
.. _Examples:
Examples
To concatenate the two MeasurementSets 'ngc5921.ms' and 'src2.ms'
into a file named 'out.mms':
::
virtualconcat(vis=['src2.ms','ngc5921.ms'], concatvis='out.mms')
The original 'ngc5921.ms' and 'src2.ms' are gone. The output data
'out.mms' is a Multi-MS. As most of the data is only moved, not
copied, this is faster and subsequent tasks can run in parallel on
the Sub-MSs of 'out.mms'.
To concatenate the two MeasurementSets 'ngc5921.ms' and 'src2.ms'
into a file named 'out.mms', but keeping the original
MeasurementSets:
::
virtualconcat(vis=['src2.ms','ngc5921.ms'], concatvis='out.mms', keepcopy=True)
Compared to the first example, this consumes more disk space and
time for the copy.
.. note:: NOTE: Run flagmanager to save flags in the concatvis.
.. _Development:
Development
No additional development details
.. _Details:
Parameter Details
Detailed descriptions of each function parameter
.. _vis:
| ``vis (stringArray)`` - List of names of input visibility files to be concatenated
.. _concatvis:
| ``concatvis (string='')`` - Name of the output visibility file (a multi-MS)
.. _freqtol:
| ``freqtol (variant='')`` - Frequency shift tolerance for considering data as the same spwid
.. _dirtol:
| ``dirtol (variant='')`` - Direction shift tolerance for considering data as the same field
.. _respectname:
| ``respectname (bool=True)`` - If true, fields with a different name are not merged even if their direction agrees
.. _visweightscale:
| ``visweightscale (doubleArray=[''])`` - List of the weight scaling factors to be applied to the individual MSs
.. _keepcopy:
| ``keepcopy (bool=False)`` - If true, a copy of the input MSs is kept in their original place.
.. _copypointing:
| ``copypointing (bool=True)`` - If true, keep the POINTING table information in the output MMS. If false, don\'t.
"""
pass