MS-Selection Improvements

CASA Modification Request 24C108, November 2007

1. Introduction

The MS-selection is the general method which is used by many tasks in order to select the appropriate data for processing. The present implementation of the ms-selection still lacks some of the features that were in the design document.

2. Background

3. Requirements

Complete the ms-selection requirements. They are:

1. Handling of velocity ranges and increments

  • ALERT! After some thought and discussions with others, I feel velocity based selection in MSSelection is not possible without making the syntax and its implementation more complicated. Conversion from velocity to frequency requires velocity frame and rest frequency information (this is source dependent). This, particularly the latter, in the case of multiple SPWs and/or multiple fields and for wide-bands is complicated (and also require frequency selection and field selection expressions to be coupled...this will make the implementation more complex and less maintainable, etc.). Velocity based selection as part of MSSelection is therefore not a good idea.

2. Introduce the negation syntax '!'. That is antenna = '!3,!4' means include all antennas except 3 and 4.

  • DONE Syntax: This has been checked into the system now. The negation operator '!' is a baseline operator. So the do the above (include all baselines except those with antennas 3 and 4) the expression would be "!3~4" or "!3;!4".

  • For the programmers: The list of selected antennas and baselines with now come with a negative size for those antennas/baseline on which the negation operator was applied. These baselines will not be in the selected MS.

  • For all: Please test.

3. Remove the use of nchan, step, start and width and replace with ms-selection syntax in appropriate tasks.

  • List out the tasks where this change is required, please.

4. Design

5. Deployment Checklist

6. Test Plan

6.1 Internal Testing

  • Done. Requested others in the CASA group to test as well.

6.2 Sponsor Testing

  • Requested S. Myers and D. Whysong to start testing.

6.3 Integration/Regression Tests

6.4 Testing for Scientific Validity


APPROVED: I acknowledge that my request is fully contained in this MR, and if the CASA development group delivers exactly what I specified, I will be happy.

ACCEPTED: I acknowledge that I have validated the completed code according to the acceptance tests, and I am happy with the results.

Written - - - - -
Checked - - - - -
Approved by Scientific Sponsor - - - - -
Accepted/Delivered by Sponsor - - - - -

  • Use %X% if MR is not complete (will display ALERT!)
  • Use %Y% if MR iscomplete (will display DONE)

Discussion Area

-- NicoleRadziwill - 30 Oct 2007

-- EdFomalont - 06 Nov 2007

-- EdFomalont - 07 Nov 2007
Topic revision: r4 - 2008-01-10, SanjayBhatnagar
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