vishead

vishead(vis, mode='summary', listitems=['telescope', 'observer', 'project', 'field', 'freq_group_name', 'spw_name', 'schedule', 'schedule_type', 'release_date'], hdkey='', hdindex='', hdvalue='')[source]

List, summary, get, and put metadata in a measurement set

[Description] [Examples] [Development] [Details]

Parameters

  • vis (path) - Name of input visibility file

  • mode (string=’summary’) - Mode of operation for vishead

    mode = list

    • listitems (stringVec=[‘telescope’, ‘observer’, ‘project’, ‘field’, ‘freq_group_name’, ‘spw_name’, ‘schedule’, ‘schedule_type’, ‘release_date’]) - Keyword items to list. This parameter is only relevant in list mode. Note that the default list is a subset of the possible keywords. To get all the keywords set listitems=[]

    mode = get

    • hdkey (string=’’) - Keyword to get/put

    • hdindex (string=’’) - Index (counting from 0) if keyword is an array (used in get/put mode only). The empty string means all elements

    mode = put

    • hdkey (string=’’) - Keyword to get/put

    • hdindex (string=’’) - Index (counting from 0) if keyword is an array (used in get/put mode only). The empty string means all elements

    • hdvalue (variant=’’) - Value of the keywords to be put in the MS (used in put mode only)

Returns

out (tuple or dict) - when mode=’get’, tuple with the value of the requested keyword, and associated metainformation if available. When mode=’list’, a dictionary containing the values of each keyword given in the listitems parameter

Description

This task allows the user to manipulate some meta-data keywords 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 with mode=’get’ and changed with mode=’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: Provides a summary that is equivalent to running listobs(verbose=False)

  • get: Get the specified keyword value(s) from the ms

  • put: Put the specified keyword value(s) into the ms

Keywords currently implemented are:

  • 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

  • source_name

  • telescope (Telescope Name)

Note that the default list of keywords is a subset of the former list. To get all the keywords mentioned above set listitemts=[]. See the Parameter pages of vishead for more details.

More information can also be found in the CASA Docs pages on Listing and Changing MS Metadata.

Examples

To list the available keywords in a MeasurementSet:

vishead(vis='measurementset.ms',mode='list')

To get the values for the phase center:

vishead(vis='measurementset.ms',mode='get',hdkey='ptcs',hdindex='1')

In this example, hdvalue [0][0] gives the RA, while hdvalue [0][1] gives the DEC in field ‘1’.

To get the name for field 2:

vishead(vis='measurementset.ms',mode='get',hdkey='field',hdindex='2')

To change the name for field 2 into “junk”.

vishead(vis='measurementset.ms',mode='put',hdkey='field',hdindex='2',hdvalue='junk')

Note

NOTE: To transfer the parameters to useful python items requires some care. Changing a number (e.g. RA of field=1 to 0.5 radian) may be complicated to figure out.

Development

No additional development details

Parameter Details

Detailed descriptions of each function parameter

vis (path) - Name of input visibility file
mode (string='summary') - Mode of operation for vishead
listitems (stringVec=['telescope', 'observer', 'project', 'field', 'freq_group_name', 'spw_name', 'schedule', 'schedule_type', 'release_date']) - Keyword items to list. This parameter is only relevant in list mode. Note that the default list is a subset of the possible keywords. To get all the keywords set listitems=[]
hdkey (string='') - Keyword to get/put
hdindex (string='') - Index (counting from 0) if keyword is an array (used in get/put mode only). The empty string means all elements
hdvalue (variant='') - Value of the keywords to be put in the MS (used in put mode only)