feat(event): add support for Earth seasons (#24)

* chore: fix files to commit on tag

* fix(ephemerides): fix a bug that made the ephemerides calculations impossible for the Poles (#21)

* chore: fix the target branch on Dependabot's config

* ci: remove Commitlint workflow (replaced by semantic-pull-request) (#25)

* ci: remove Commitlint workflow (replaced by semantic-pull-request)

* ci: fix doctests not running correctly on some OS and Python versions

* Add season change event in events.py and enum.py

* Add minor change in season change event

* Add documentation, change enum constants, change output object of _search_earth_season_change

* Minor changes to _search_earth_season_change

* Update EventType enum, update class of details

* Fix minor bugs

* docs: Update docs for _search_earth_season_change and _search_conjunction.chore: make minor changes to _search_earth_season_change

* Update: minor changes to match Python coding style.

* Update: minor changes to match Python coding style. Docs: update docstring of _search_earth_season_change and _search_conjunction

* test:update legacy tests for events.py. update: update enum.py and events.py to match black coding style.

* Fix some minor issues with Black and Event.details field

Co-authored-by: Jérôme Deuchnord <jerome@deuchnord.fr>
Co-authored-by: Jérôme Deuchnord <Deuchnord@users.noreply.github.com>

BREAKING CHANGE: the `Event.details` field is now a dictionary (was previously a string).

kosmorrolib/enum.py

@@ -1,6 +1,6 @@
 #!/usr/bin/env python3
 
-from enum import Enum, auto
+from enum import Enum
 
 
 class MoonPhaseType(Enum):
@@ -16,6 +16,13 @@ class MoonPhaseType(Enum):
     WANING_CRESCENT = 8
 
 
+class SeasonType(Enum):
+    MARCH_EQUINOX = 0
+    JUNE_SOLSTICE = 1
+    SEPTEMBER_EQUINOX = 2
+    DECEMBER_SOLSTICE = 3
+
+
 class EventType(Enum):
     """An enumeration for the supported event types."""
 
@@ -25,6 +32,7 @@ class EventType(Enum):
     MAXIMAL_ELONGATION = 4
     MOON_PERIGEE = 5
     MOON_APOGEE = 6
+    SEASON_CHANGE = 7
 
 
 class ObjectType(Enum):

kosmorrolib/events.py

@@ -5,16 +5,34 @@
 from skyfield.errors import EphemerisRangeError
 from skyfield.timelib import Time
 from skyfield.searchlib import find_discrete, find_maxima, find_minima
+from skyfield import almanac
 from numpy import pi
 
-from .model import Event, Star, Planet, ASTERS
-from .dateutil import translate_to_timezone
-from .enum import EventType, ObjectIdentifier
-from .exceptions import OutOfRangeDateError
-from .core import get_timescale, get_skf_objects, flatten_list
+from kosmorrolib.model import Event, Star, Planet, ASTERS
+from kosmorrolib.dateutil import translate_to_timezone
+from kosmorrolib.enum import EventType, ObjectIdentifier, SeasonType
+from kosmorrolib.exceptions import OutOfRangeDateError
+from kosmorrolib.core import get_timescale, get_skf_objects, flatten_list
 
 
 def _search_conjunction(start_time: Time, end_time: Time, timezone: int) -> [Event]:
+    """Function to search conjunction.
+
+    **Warning:** this is an internal function, not intended for use by end-developers.
+
+    Will return MOON and VENUS opposition on 2021-06-12:
+
+    >>> conjunction = _search_conjunction(get_timescale().utc(2021,6,12),get_timescale().utc(2021,6,13),0)
+    >>> len(conjunction)
+    1
+    >>> conjunction[0].objects
+    [<Object type=SATELLITE name=MOON />, <Object type=PLANET name=VENUS />]
+
+    Will return nothing if no conjunction happens:
+
+    >>> _search_conjunction(get_timescale().utc(2021,6,17),get_timescale().utc(2021,6,18),0)
+    []
+    """
     earth = get_skf_objects()["earth"]
     aster1 = None
     aster2 = None
@@ -177,13 +195,13 @@ def get_elongation(time: Time):
         )
 
         for i, time in enumerate(times):
-            elongation = elongations[i]
+            elongation = round(elongations[i], 1)
             events.append(
                 Event(
                     EventType.MAXIMAL_ELONGATION,
                     [aster],
                     translate_to_timezone(time.utc_datetime(), timezone),
-                    details="{:.3n}°".format(elongation),
+                    details={"deg": elongation},
                 )
             )
 
@@ -245,6 +263,45 @@ def _search_moon_perigee(start_time: Time, end_time: Time, timezone: int) -> [Ev
     return events
 
 
+def _search_earth_season_change(
+    start_time: Time, end_time: Time, timezone: int
+) -> [Event]:
+    """Function to find earth season change event.
+
+    **Warning:** this is an internal function, not intended for use by end-developers.
+
+    Will return JUNE SOLSTICE on 2020/06/20:
+
+    >>> season_change = _search_earth_season_change(get_timescale().utc(2020, 6, 20), get_timescale().utc(2020, 6, 21), 0)
+    >>> len(season_change)
+    1
+    >>> season_change[0].event_type
+    <EventType.SEASON_CHANGE: 7>
+    >>> season_change[0].details
+    {'season': <SeasonType.JUNE_SOLSTICE: 1>}
+
+    Will return nothing if there is no season change event in the period of time being calculated:
+
+    >>> _search_earth_season_change(get_timescale().utc(2021, 6, 17), get_timescale().utc(2021, 6, 18), 0)
+    []
+    """
+    events = []
+    event_time, event_id = almanac.find_discrete(
+        start_time, end_time, almanac.seasons(get_skf_objects())
+    )
+    if len(event_time) == 0:
+        return []
+    events.append(
+        Event(
+            EventType.SEASON_CHANGE,
+            [],
+            translate_to_timezone(event_time.utc_datetime()[0], timezone),
+            details={"season": SeasonType(event_id[0])},
+        )
+    )
+    return events
+
+
 def get_events(for_date: date = date.today(), timezone: int = 0) -> [Event]:
     """Calculate and return a list of events for the given date, adjusted to the given timezone if any.
 
@@ -265,7 +322,7 @@ def get_events(for_date: date = date.today(), timezone: int = 0) -> [Event]:
 
     If there is no events for the given date, then an empty list is returned:
 
-    >>> get_events(date(2021, 3, 20))
+    >>> get_events(date(2021, 4, 20))
     []
 
     :param for_date: the date for which the events must be calculated
@@ -289,6 +346,7 @@ def get_events(for_date: date = date.today(), timezone: int = 0) -> [Event]:
             _search_maximal_elongations,
             _search_moon_apogee,
             _search_moon_perigee,
+            _search_earth_season_change,
         ]:
             found_events.append(fun(start_time, end_time, timezone))
 

kosmorrolib/model.py

@@ -154,7 +154,7 @@ def __init__(
         objects: [Object],
         start_time: datetime,
         end_time: Union[datetime, None] = None,
-        details: str = None,
+        details: {str: any} = None,
     ):
         self.event_type = event_type
         self.objects = objects

tests/events.py

@@ -74,7 +74,7 @@
                 EventType.MAXIMAL_ELONGATION,
                 [ASTERS[2]],
                 datetime(2020, 2, 10, 13, 46),
-                details="18.2°",
+                details={"deg": 18.2},
             ),
             Event(EventType.MOON_PERIGEE, [ASTERS[1]], datetime(2020, 2, 10, 20, 34)),
         ],
@@ -86,14 +86,14 @@
                 EventType.MAXIMAL_ELONGATION,
                 [ASTERS[2]],
                 datetime(2020, 3, 24, 1, 56),
-                details="27.8°",
+                details={"deg": 27.8},
             ),
             Event(EventType.MOON_APOGEE, [ASTERS[1]], datetime(2020, 3, 24, 15, 39)),
             Event(
                 EventType.MAXIMAL_ELONGATION,
                 [ASTERS[3]],
                 datetime(2020, 3, 24, 21, 58),
-                details="46.1°",
+                details={"deg": 46.1},
             ),
         ],
     ),