updating Vac mvm (visual_morphology script)

[jvazquez77]

Fixes #

This pull request:

• Has a title that summarises what is changing.
• Updates the documentation accordingly.
• Has unit tests & code coverage is not adversely affected (within reason).
• Works with Python 2.7 and 3.6 (and ideally with Python 3.7).
• Updates the CHANGELOG.
• Removes more lines of code than it adds.
• If relevant, adds a new entry to the What's new? page.

[havok2063]

@jvazquez77 Since Marvin will support both DR16 and DR17 public data releases, your VAC will need to support both versions as well. I think you'll need to keep the old logic in some form to sort out the survey images from DR16, but modify the code to also work with the simpler DR17 images. Let me know if you want to iterate over ideas.

[jvazquez77]

Hi @havok2063
Thanks for your comment. In the new set of images (DR17), we have combined the most important information from the 2 sets in DR16, and also we have corrected different errors. In this sense we think it is much better just to present the last version of images. On the other hand, please let me know if you consider Marvin must keep available both versions, I am happy modify the code and iterate over ideas.

[havok2063]

Hi @jvazquez77, yeah I think since Marvin will be backwards compatible with DR16 I think your VAC needs to be as well. Some users might access targets for DR16, and if they access your VAC for that target, we want the VAC to work as expected with the old data. The old data will still exist on the SAS and users can in principle use it. I agree that we want users to use the updated DR17 dataset. In that case, one idea could be to issue a warning when users are accessing your DR16 VAC data, to instruct them to try the updated data. E.g. in the get_target method, somewhere in the beginning, you can add something like

if parent_object.release == 'DR16':
    log.warning('You are accessing outdated DR16 data for this VAC.  This target has updated data in DR17.  We recommend using the new data release instead.')

or whatever message you would like to say. You would need to add a from marvin import log at the top.

[jvazquez77]

@havok2063 I did the proposed changes, so I think now it is working fine, either for the DR16 or the DR17 version.
Please let me know if there is any comment.