Allow explicit UTC offset to be passed to bypass timezone lookup.

Author: theriftlab

immanuel/charts.py

@@ -30,14 +30,15 @@
 class Subject:
     """ Simple class to model a chart subject - essentially just
     a time and place. """
-    def __init__(self, date_time: datetime | str, latitude: float | list | tuple | str, longitude: float | list | tuple | str, time_is_dst: bool = None) -> None:
+    def __init__(self, date_time: str | float | datetime, latitude: float | list | tuple | str, longitude: float | list | tuple | str, timezone_offset: float = None, time_is_dst: bool = None) -> None:
         self.latitude, self.longitude = (convert.to_dec(v) for v in (latitude, longitude))
         self.time_is_dst = time_is_dst
         self.date_time = date.to_datetime(
                 dt=date_time,
                 lat=self.latitude,
                 lon=self.longitude,
-                is_dst=time_is_dst
+                offset=timezone_offset,
+                is_dst=time_is_dst,
             )
         self.date_time_ambiguous = date.ambiguous(self.date_time) and time_is_dst is None
         self.julian_date = date.to_jd(self.date_time)
@@ -449,7 +450,7 @@ class Transits(Chart):
     to the natal chart. Coordinates default to those specified in settings. """
     def __init__(self, latitude: float | list | tuple | str = settings.default_latitude, longitude: float | list | tuple | str = settings.default_longitude, aspects_to: Chart = None) -> None:
         lat, lon = (convert.to_dec(v) for v in (latitude, longitude))
-        timezone = date.timezone(lat, lon)
+        timezone = date.timezone_name(lat, lon)
         date_time = datetime.now(tz=ZoneInfo(timezone))
         self._native = Subject(date_time, lat, lon)
         super().__init__(chart.TRANSITS, aspects_to)

immanuel/tools/date.py

@@ -14,7 +14,7 @@
 
 """
 
-from datetime import datetime
+from datetime import datetime, timedelta, timezone
 from zoneinfo import ZoneInfo
 
 import swisseph as swe
@@ -29,37 +29,39 @@ def ambiguous(dt: datetime) -> bool:
     return tz.datetime_ambiguous(dt)
 
 
-def timezone(lat: float, lon: float) -> str:
+def timezone_name(lat: float, lon: float) -> str:
     """ Returns a timezone string based on decimal lat/lon coordinates. """
     return TimezoneFinder().timezone_at(lat=lat, lng=lon)
 
 
-def localize(dt: datetime, lat: float, lon: float, is_dst: bool = None) -> datetime:
-    """ Localizes a naive datetime based on decimal lat/lon coordinates. """
-    return dt.replace(tzinfo=ZoneInfo(timezone(lat, lon)), fold=1 if is_dst is False else 0)
+def localize(dt: datetime, lat: float, lon: float, offset: float = None, is_dst: bool = None) -> datetime:
+    """ Localizes a naive datetime based on either decimal lat/lon
+    coordinates or an explicit UTC offset. """
+    zone = ZoneInfo(timezone_name(lat, lon)) if offset is None else timezone(timedelta(hours=offset))
+    return dt.replace(tzinfo=zone, fold=1 if is_dst is False else 0)
 
 
-def to_datetime(dt: str | float | datetime, lat: float = None, lon: float = None, is_dst: bool = None) -> datetime:
+def to_datetime(dt: str | float | datetime, lat: float = None, lon: float = None, offset: float = None, is_dst: bool = None) -> datetime:
     """ Convert an unknown into a datetime. Unknowns can be either an
     ISO-formatted string, a Julian Date, or already a datetime. """
     no_coords = lat is None or lon is None
     if isinstance(dt, str):
         date_time = datetime.fromisoformat(dt)
-        return date_time.replace(tzinfo=ZoneInfo('UTC')) if no_coords else localize(date_time, lat, lon, is_dst)
+        return date_time.replace(tzinfo=ZoneInfo('UTC')) if no_coords else localize(date_time, lat, lon, offset, is_dst)
     if isinstance(dt, float):
         ut = swe.revjul(dt)
         time = convert.dec_to_dms(ut[3])[1:]
         date_time = datetime(*ut[:3], *time, tzinfo=ZoneInfo('UTC'))
-        return date_time if no_coords else date_time.astimezone(ZoneInfo(timezone(lat, lon)))
+        return date_time if no_coords else date_time.astimezone(ZoneInfo(timezone_name(lat, lon)))
     if isinstance(dt, datetime):
         if no_coords:
             return dt.replace(tzinfo=ZoneInfo('UTC')) if dt.tzinfo is None else dt
         else:
-            return localize(dt, lat, lon, is_dst)
+            return localize(dt, lat, lon, offset, is_dst)
     return None
 
 
-def to_jd(dt: str | float | datetime, lat: float = None, lon: float = None, is_dst: bool = None) -> float:
+def to_jd(dt: str | float | datetime, lat: float = None, lon: float = None, offset: float = None, is_dst: bool = None) -> float:
     """ Convert an unknown into a Julian date. Unknowns can be either an
     ISO-formatted string, already a Julian Date, or a datetime. """
     if isinstance(dt, float):
@@ -72,7 +74,7 @@ def to_jd(dt: str | float | datetime, lat: float = None, lon: float = None, is_d
         return None
 
     if lat is not None and lon is not None:
-        date_time = localize(date_time, lat, lon, is_dst)
+        date_time = localize(date_time, lat, lon, offset, is_dst)
     elif date_time.tzinfo is None:
         date_time = date_time.replace(tzinfo=ZoneInfo('UTC'))
 

tests/test_date.py

@@ -50,11 +50,11 @@ def jd():
 
 
 def test_timezone_gmt(gmt_coords):
-    assert date.timezone(*gmt_coords) == 'Europe/London'
+    assert date.timezone_name(*gmt_coords) == 'Europe/London'
 
 
 def test_timezone_pst(pst_coords):
-    assert date.timezone(*pst_coords) == 'America/Los_Angeles'
+    assert date.timezone_name(*pst_coords) == 'America/Los_Angeles'
 
 
 def test_localize(pst_coords):
@@ -64,8 +64,8 @@ def test_localize(pst_coords):
 
 
 def test_localize_dst(ambiguous_date, pst_coords):
-    dt_no_dst = date.localize(ambiguous_date, *pst_coords, False)
-    dt_dst = date.localize(ambiguous_date, *pst_coords, True)
+    dt_no_dst = date.localize(ambiguous_date, *pst_coords, is_dst=False)
+    dt_dst = date.localize(ambiguous_date, *pst_coords, is_dst=True)
     jd_no_dst = date.to_jd(dt_no_dst)
     jd_dst = date.to_jd(dt_dst)
     assert dt_no_dst.hour == dt_dst.hour