Improvements to plotxy

CASA Modification Request 2C108, November 2007

1. Introduction

The task plotxy needs several enhancements: 1) Both time and channels should have both amplitude and scalar averaging; 2) Better labeling needed for plots, especially for multi-panel plots; 3) Parameter windowsize does not work; 4) direct ouput to postscript or other format without plotting (good for automatic scripts); 5) correlator as an iteration option; 6) plotoption 'BOTH' for 'RR LL' or 'XX YY'; 7) apply calibration on the fly to see results for calibrated data with running applycal first; 8) extend the scope of the edit beyond what is plotted. See[][JIRA Ticket CAS-197]] for details.

2. Background

3. Requirements

Several improvements are needed for plotxy.

3.1 Scalar versus Vector averaging in time and channel

This has the highest priority of plotxy improvements. The vector averaging over time and/or channel should be the default since averaging is generally done in order to detect weak signals in the data. The arithmetic average (scalar averaging of amplitude, but vector average of the phase) should be another option. At the present time, the averaging is done on the amplitude and phase independently and is not useful, especially for the phase which will always tend to near zero phase for weak sources.

At present, the time averaging is very slow and a appears to be caused by a table sort once time averaging is specified. Determining average quantities on the fly would work much faster.


Better plot labeling needed, especially for the x-axis as time. First, the number of ticks along this axis should be between 3 and 6; hence a better time increment should be chosen. Second, the HH:MM:SS is all that is needed. Third, The label on top of the plot is a repeat of the y-label and x-label, so is redundant. If iteration is used, that should be on the top label


Applying the calibration on the fly would be a useful option for plotxy. This would avoid the use of applycal to check the results from several calibration tables.


It would be useful to run plotxy in a script that produced the plot in a hard copy form. At the present time, this can only be done interactively.


The other improvements are self-explanatory.

4. Design

5. Deployment Checklist

6. Test Plan

6.1 Internal Testing

6.2 Sponsor Testing

Check if the averaging in time is working properly. Other improvements can be checked trivially.

6.3 Integration/Regression Tests

6.4 Testing for Scientific Validity

Check that time averaging (vector and scalar) are working properly using a suitable data base.


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 - 01 Nov 2007
Topic revision: r5 - 2007-11-26, EdFomalont
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