diff options
Diffstat (limited to 'backend/hist_data/cal.py')
| -rw-r--r-- | backend/hist_data/cal.py | 30 |
1 files changed, 14 insertions, 16 deletions
diff --git a/backend/hist_data/cal.py b/backend/hist_data/cal.py index 3b65205..550303e 100644 --- a/backend/hist_data/cal.py +++ b/backend/hist_data/cal.py @@ -1,14 +1,14 @@ """ Provides date conversion functions, HistDate, and date scales. -Algorithms for converting between calendars and Julian day number values were obtained from -https://en.wikipedia.org/wiki/Julian_day#Converting_Gregorian_calendar_date_to_Julian_Day_Number. """ +# For conversion between calendars and Julian day numbers. Algorithms were obtained from +# https://en.wikipedia.org/wiki/Julian_day#Converting_Gregorian_calendar_date_to_Julian_Day_Number. def gregorianToJdn(year: int, month: int, day: int) -> int: """ Converts a Gregorian calendar date to a Julian day number, denoting the noon-to-noon 'Julian day' that starts within the input day. - A year of 1 means 1 CE, and -1 means 1 BC (0 is treated like -1). + A year of 1 means 1 AD, and -1 means 1 BC (0 is treated like -1). A month of 1 means January. Can use a month of 13 and a day of 0. Valid for dates from 24th Nov 4714 BC onwards. """ @@ -20,7 +20,6 @@ def gregorianToJdn(year: int, month: int, day: int) -> int: jdn -= int((3 * int((year + 4900 + x) / 100)) / 4) jdn += day - 32075 return jdn - def julianToJdn(year: int, month: int, day: int) -> int: """ Like gregorianToJdn(), but converts a Julian calendar date. @@ -33,7 +32,6 @@ def julianToJdn(year: int, month: int, day: int) -> int: jdn += int(275 * month / 9) jdn += day + 1729777 return jdn - def jdnToGregorian(jdn: int) -> tuple[int, int, int]: """ Converts a Julian day number to a Gregorian calendar date, denoting the @@ -50,7 +48,6 @@ def jdnToGregorian(jdn: int) -> tuple[int, int, int]: if Y <= 0: Y -= 1 return Y, M, D - def jdnToJulian(jdn: int) -> tuple[int, int, int]: """ Like jdnToGregorian(), but converts to a Julian calendar date """ f = jdn + 1401 @@ -63,26 +60,25 @@ def jdnToJulian(jdn: int) -> tuple[int, int, int]: if Y <= 0: Y -= 1 return Y, M, D - def julianToGregorian(year: int, month: int, day: int) -> tuple[int, int, int]: return jdnToGregorian(julianToJdn(year, month, day)) - def gregorianToJulian(year: int, month: int, day: int) -> tuple[int, int, int]: return jdnToJulian(gregorianToJdn(year, month, day)) -MIN_CAL_YEAR = -4713 # Disallow within-year dates before this year +# For date representation +MIN_CAL_YEAR = -4713 # Year before which JDNs are not usable MONTH_SCALE = -1; DAY_SCALE = -2; -SCALES: list[int] = [int(x) for x in [1e9, 1e8, 1e7, 1e6, 1e5, 1e4, 1e3, 100, 10, 1, MONTH_SCALE, DAY_SCALE]]; +SCALES: list[int] = [int(s) for s in [1e9, 1e8, 1e7, 1e6, 1e5, 1e4, 1e3, 100, 10, 1, MONTH_SCALE, DAY_SCALE]]; class HistDate: """ Represents a historical date - - 'year' may be negative (-1 means 1 BCE) + - 'year' may be negative (-1 means 1 BC) - 'month' and 'day' are at least 1, if given - 'gcal' may be: - True: Indicates a Gregorian calendar date - False: Means the date should, for display, be converted to a Julian calendar date - - None: 'month' and 'day' are 1 (used for dates before the Julian period starting year 4713 BCE) + - None: 'month' and 'day' are 1 (required for dates before MIN_CAL_YEAR) """ def __init__(self, gcal: bool | None, year: int, month=1, day=1): self.gcal = gcal @@ -96,22 +92,24 @@ class HistDate: def __repr__(self): return str(self.__dict__) def dbDateToHistDate(n: int, fmt: int, end=False) -> HistDate: + """ Converts a start/start_upper/etc and fmt value in the 'events' db table, into a HistDate """ if fmt == 0: # year if n >= MIN_CAL_YEAR: return HistDate(True, n, 1, 1) else: return HistDate(None, n) - elif fmt == 1 or fmt == 3 and not end: # jdn for julian calendar - return HistDate(False, *jdnToJulian(n)) - else: # fmt == 2 or fmt == 3 and end + elif fmt == 1 or fmt == 3 and end: # jdn for gregorian calendar return HistDate(True, *jdnToGregorian(n)) + else: # fmt == 2 or fmt == 3 and not end + return HistDate(False, *jdnToJulian(n)) def dateToUnit(date: HistDate, scale: int) -> int: + """ Converts a date to an int representing a unit on a scale """ if scale >= 1: return date.year // scale elif scale == MONTH_SCALE: if date.gcal == False: return julianToJdn(date.year, date.month, 1) - else: + else: # True or None return gregorianToJdn(date.year, date.month, 1) else: # scale == DAY_SCALE if date.gcal == False: |