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When initialized with a `year`, returns a class with a number of date attributes corresponding to common feasts of the western liturgical calendar. Number of Sundays after Epiphany and Trinity / Pentecost are also calculated, and stored in attributes. If the optional parameter `v2` is set to True, the calendar will return a post-Vatican II calendar which changes the date of Transfiguration Sunday, and the number of Sundays after Epiphany. In either case, the pre-Lent Sundays and Sundays after Pentecost will be set.

Note: The `year` parameter is the year of the First Sunday in Advent - the beginning of the church year, and the resulting calendar thus ends in the following year.

Python, 81 lines
 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81``` ```from datetime import date, timedelta class LiturgicalYear: def __init__(self, year, v2 = False): #v2 = "Vatican II" and refers to the reforms made to the calendar #which were adopted my many Protestant denominations in the 1970's #The only significant change for our purposes, is the date of #Transfiguration Sunday, which in turn is used to calculate the number #of Sundays after Epiphany. self.init_calendar(year, v2) def calc_easter(self, year): "Returns easter as a date object." a = year % 19 b = year // 100 c = year % 100 d = (19 * a + b - b // 4 - ((b - (b + 8) // 25 + 1) // 3) + 15) % 30 e = (32 + 2 * (b % 4) + 2 * (c // 4) - d - (c % 4)) % 7 f = d + e - 7 * ((a + 11 * d + 22 * e) // 451) + 114 month = f // 31 day = f % 31 + 1 return date(year, month, day) def init_calendar(self, year, v2 = False): self.vatican2 = v2 self.easter = self.calc_easter(year + 1) #The first Sunday in Advent is always on or after November 27th nov27day = date(year, 11, 27).isoweekday() if nov27day == 7: self.advent1 = date(year, 11, 27) else: self.advent1 = date(year, 11, 27) + timedelta(7 - nov27day) self.advent4 = self.advent1 + timedelta(21) #Now calculate the date of the next First Sunday in Advent in order to #calculate Sundays after Trinity. nov27day = date(year + 1, 11, 27).isoweekday() if nov27day == 7: next_advent1 = date(year + 1, 11, 27) else: next_advent1 = date(year + 1, 11, 27) + timedelta(7 - nov27day) #First Sunday after Epiphany jan6day = date(year + 1, 1, 6).isoweekday() if jan6day == 7: self.epiphany1 = date(year + 1, 1, 13) else: self.epiphany1 = date(year + 1, 1, 13) - timedelta(jan6day) #A bunch of easy ones: self.epiphany = date(year + 1, 1, 6) if v2: self.transfiguration = self.easter - timedelta(49) else: self.transfiguration = self.easter - timedelta(70) self.septuagesima = self.easter - timedelta(63) self.ashWednesday = self.easter - timedelta(46) self.maundyThursday = self.easter - timedelta(3) self.goodFriday = self.easter - timedelta(2) self.palmSunday = self.easter + timedelta(7) self.ascension = self.easter + timedelta(39) self.pentecost = self.easter + timedelta(49) self.trinity = self.easter + timedelta(56) self.trinityLast = next_advent1 - timedelta(7) self.pentecostLast = self.trinityLast #Sundays after Epiphany and Trinity/Pentecost #Note: Epiphany Sundays include Transfiguration self.epiphanySundays = (self.transfiguration - self.epiphany1).days / 7 + 1 self.trinitySundays = (next_advent1 - self.trinity).days / 7 - 1 self.pentecostSundays = self.trinitySundays + 1 #And finally, American Thanksgiving - which shouldn't even be here, #but too many people complain if it's not: nov1day = date(year + 1, 11, 1).isoweekday() if nov1day <= 4: self.thanksgiving = date(year + 1, 11, 26 - nov1day) else: self.thanksgiving = date(year + 1, 11, 33 - nov1day) ```

Bob Oelschlaeger 15 years, 7 months ago

I think that

``````    self.palmSunday = self.easter + timedelta(7)
``````

should be

``````    self.palmSunday = self.easter - timedelta(7)
``````
Richard Philips 15 years, 7 months ago

... and:

I think that:

self.ashWednesday = self.easter - timedelta(46)

should be:

self.ashWednesday = self.easter - timedelta(39)

 Created by Martin Diers on Tue, 30 Sep 2008 (MIT)