New Chord and ChordList classes

[altairgomes]

New features are being introduced. These are new classes Chord and ChordList which will intermediate between the Occultation class and the Observer and LightCurve classes. These new classes are not new modules, but they are part of the occultation module. A new List class was also introduced as a Base Class for other list classes that may be created for SORA, for instance, RingList.

• The concept of "segment" is introduced. "Segment" is an interval or group of intervals of the lightcurve corresponding to a feature. For instance, the "positive" segment corresponds to the interval between the immersion and emersion times. The 'outer' segment corresponds to the interval between the start and immersion times and between the emersion and end times. The idea is that, in the future, "segment" can be used to select between different features, like the main body occultation and the ring occultation.
• Chord:
  • A Chord instance is defined by an Observer and a Lightcurve.
  • It has the ability to enable and disable immersion or emersion that will be used in the fitting.
  • When associated with an Occultation, it can calculate the on-sky position of the occulting object for the given observer at a given time.
  • When associated with an Occultation, it can calculate the on-sky path of the occulting object for the given observer for a given segment. This fixes #30 where the user can now get the path with a small step between points.
  • When associated with an Occultation, it can plot the on-sky path of the occulting object for the given observer for a given segment.
• List:
  • A "List" is a Base Class to handle list of objects, naming each one of them, as in a dictionary, and handling iterations for the purpose of SORA. It was created to avoid repetition between future list created in the package.
• ChordList:
  • The "ChordList" is a collection of Chord instances. It is attached to the Occultation object and is not directly defined by the user.
  • It has similar functions as Chord, where it will iterate through all chords and apply the function, for instance enabling and disabling the chords for the fit and plotting the chords.
• The occultation module was adapted to the implementation of the new Chord and ChordList classes.
• Observer and LightCurve name attributes are not required to be unique anymore. The name can be given directly to Chord.
  • With the name not being required, the del() function was removed, which fixes #5.

[altairgomes]

1. If we instantiate the Occultation using Ephem instead of Body, a error occurred;

What error? Does Ephem have a name to search in the SBDB? If it is a satellite, it should be instantiated with Body. If there is an error, it's not for this PR.

2. There is a bug in the Occultation.get_map_sites(), all the stations are colored as red;

I'll look into it. They should all be red if no chord is positive.

3. If we add a chord using Occultation.Chords.add_chord(), using the object chord as input there is a error;

How do you define the chord? If it is a chord that's already added, it won't add it again.

4. Occultation.plot_chords(all_chords=False) is not ignoring the disabled chords.

I'll look into it.

1. It seems that del(Chord) do not eliminate the name from the list;

if you mean

c = occ.chords.add_chord(...)
del(c)

That's is how python works. c is not the object, is a pointer to the object. If you want to remove from the list, you should use occ.chords.remove_chord(name="name_of_chord") Even if you do that, cwill still point for the object, that is not attached to any Occultation.

2. I think Chord.get_fg() should have a warning considering the imputed time, similar to Occultation.new_astrometrical_position();

Ok.

3. Occultation.Chords.plot_chords() should have a kwarg similar to All_chords. Instead of only the kwarg ignore;

Ok.

4. I'm not sure if the Chord.path() is useful to the user, maybe it should be a hidden function.

I think hidden function are those we do not want for the user to run. Maybe because they may generate an error, or whose calls should be limited. This is not the case for the path function. If a user wants to use, it is there available.

[Bmorgado19]

Approved, please update the Releases.rst