lunarcalbase.py

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

''' generate Chinese Lunar Calendar by astronomical algorithms. Also mark the
Chinese Traditional Holiday based on luar calendar '''

__license__ = 'BSD'
__copyright__ = '2020, Chen Wei <weichen302@gmail.com>'
__version__ = '0.0.3'

from aa_full import findnewmoons
from aa_full import solarterm
from aa import jdptime
from aa import jdftime

__all__ = ['cn_lunarcal']

LCSTARTMONTH = 11

CN_DAY = {2: '初二',  3: '初三',  4: '初四',  5: '初五',  6: '初六',
          7: '初七',  8: '初八',  9: '初九', 10: '初十', 11: '十一',
         12: '十二', 13: '十三', 14: '十四', 15: '十五', 16: '十六',
         17: '十七', 18: '十八', 19: '十九', 20: '二十', 21: '廿一',
         22: '廿二', 23: '廿三', 24: '廿四', 25: '廿五', 26: '廿六',
         27: '廿七', 28: '廿八', 29: '廿九', 30: '三十'}

CN_MON = {1: '正月',  2: '二月',  3: '三月',    4: '四月',
          5: '五月',  6: '六月',  7: '七月',    8: '八月',
          9: '九月', 10: '十月', 11: '十一月', 12: '十二月',

         99: '閏十一月', 100: '閏十二月', 101: '閏正月',
        102: '閏二月',   103: '閏三月',   104: '閏四月',
        105: '閏五月',   106: '閏六月',   107: '閏七月',
        108: '閏八月',   109: '閏九月',   110: '閏十月',
        111: '閏十一月', 112: '閏十二月'}

CN_SOLARTERM = {-120: '小雪',-105: '大雪',
                 -90: '冬至', -75: '小寒', -60: '大寒',
                 -45: '立春', -30: '雨水', -15: '惊蛰',
                   0: '春分',  15: '清明',  30: '谷雨',
                  45: '立夏',  60: '小满',  75: '芒种',
                  90: '夏至', 105: '小暑', 120: '大暑',
                 135: '立秋', 150: '处暑', 165: '白露',
                 180: '秋分', 195: '寒露', 210: '霜降',
                 225: '立冬', 240: '小雪', 255: '大雪', 270: '冬至'}

CN_SOLARTERM = {-120: '小雪',-105: '大雪',
                 -90: '冬至', -75: '小寒', -60: '大寒',
                 -45: '立春', -30: '雨水', -15: '驚蟄',
                   0: '春分',  15: '清明',  30: '穀雨',
                  45: '立夏',  60: '小滿',  75: '芒種',
                  90: '夏至', 105: '小暑', 120: '大暑',
                 135: '立秋', 150: '處暑', 165: '白露',
                 180: '秋分', 195: '寒露', 210: '霜降',
                 225: '立冬', 240: '小雪', 255: '大雪', 270: '冬至'}


# calendar for this and next year are combined to generate the final output
# cache the intermedia calendar
CALCACHE = {'cached': []}
MAXCACHE = 500  # max cached items


def find_astro(year):
    ''' find new moons and solar terms needed for calculate lunar calendar
    Arg:
        year is a integer
    Return:
        list of dictionaries
            [ {date,
               newmoon/angle,
               placeholder for month }, ... ]

        '''
    # find all solar terms from -120 to +270 degree, negative angle means
    # search backward from Vernal Equinox
    solarterms = []
    angle = -120

    while angle <= 270:
        jdst = solarterm(year, angle)
        solarterms.append([jdst, angle])
        #print angle, jdftime(jdst, tz=8, ut=True)
        angle += 15

    # search 15 newmoons start 30 days before last Winter Solstice
    nms = findnewmoons(solarterms[1][0] - 30)
    aadays = [[x, 'newmoon'] for x in nms]
    aadays.extend(solarterms)
    aadays.sort()

    # normalize all Julian Day to midnight for later compare
    tmp = [(jdptime(jdftime(d[0], '%y-%m-%d', tz=8, ut=True), '%y-%m-%d'),
               d[1]) for d in aadays]
    astro = [{'date': d[0], 'astro': d[1], 'month': None} for d in tmp]
    return astro


def mark_lunarcal_month(clc):
    ''' scan and modify the Chinese Lunar Calendar Astro list for start/end of
    Chinese Lunar year and leapmonth'''

    # scan last and this Winter Solstice
    for d in clc:
        if d['astro'] == -90:
            lastws = d['date']
        elif d['astro'] == 270:
            lcend = d['date']
            break

    # the newmoon contains last Winter Solstice marks start of CLC year
    for d in clc:
        if d['date'] <= lastws and d['astro'] == 'newmoon':
            lcstart = d['date']
        elif d['date'] > lastws:
            break

    # mark month name, 11 is the month contains Winter Solstice
    newmoondate = [d['date'] for d in clc if d['astro'] == 'newmoon']
    mname = 11
    for i in range(len(newmoondate) - 1):
        thisnm, nextnm = newmoondate[i], newmoondate[i + 1]
        if thisnm < lcstart:
            continue

        for d in clc:
            if thisnm <= d['date'] and d['date'] < nextnm:
                d['month'] = mname
            elif d['date'] >= nextnm:
                break
        mname += 1

    # trim to days between two Winter Solstice
    clc = [d for d in clc if d['date'] >= lcstart and d['date'] <= lcend]

    return scan_leap(clc)


def scan_leap(clc):
    ''' scan and change month name(number) if necessary
    Arg:
        clc: the astros trimmed to a CLC year
    Return:
        the Chinese Lunar Calendar astro with month name adjusted for leap

        '''
    lcstart, lcend = clc[0]['date'], clc[-1]['date']
    # scan for leap month
    nmcount = 0
    for d in clc:
        if (d['date'] > lcstart and d['date'] <= lcend and
                                    d['astro'] == 'newmoon'):
            nmcount += 1

    # leap year has more than 12 newmoons between two Winter Solstice
    if nmcount > 12:
        # search leap month from LC 11, to next LC 11, which = 11 + 13
        for m in range(11, 25):
            foundleap = True
            for d in clc:
                if d['astro'] == 'newmoon':
                    continue
                if d['month'] == m and d['astro'] % 30 == 0:
                    foundleap = False
            if foundleap:
                monthofleap = m
                break

        for d in clc:
            if d['month'] == monthofleap:
                d['month'] += -1 + 100  # add 100 to distinguish leap month
            elif d['month'] > monthofleap:
                d['month'] -= 1

    for d in clc:
        if d['month'] > 12:
            d['month'] -= 12

    return clc


def mark_lunarcal_day(clcmonth):
    ''' expand to whole year, mark the day of month and lunar calendar date in
    Chinese'''

    stdays= {}  # days have solar terms
    for d in clcmonth:
        if d['astro'] != 'newmoon':
            stdays[d['date']] = d['astro']


    # expand to whole year
    start = clcmonth[0]['date']
    yearend = clcmonth[-1]['date'] + 1
    lcdays = []
    while start < yearend:
        # scan the month start belongs
        for d in clcmonth:
            if d['date'] > start:
                break
            if d['astro'] == 'newmoon':
                monthstart = d['date']
                mname = d['month']

        day = {'date': start, 'month': mname, 'jieqi': None, 'holiday': None}
        day['day'] = int(start + 1 - monthstart)

        if start in stdays:
            day['jieqi'] = CN_SOLARTERM[stdays[start]]

        if day['day'] == 1:
            day['lunardate'] = CN_MON[day['month']]
        else:
            day['lunardate'] = CN_DAY[day['day']]

        lcdays.append(day)
        start += 1

    return lcdays


def mark_holiday(clcdays):
    ''' mark Chinese Traditional Holiday

    腊八节(腊月初八)     除夕(腊月的最后一天)     春节(一月一日)
    元宵节(一月十五日)   寒食节(清明的前一天)     端午节(五月初五)
    七夕节(七月初七)     中元节(七月十五日)       中秋节(八月十五日)
    重阳节(九月九日)     下元节(十月十五日)

    '''

    for i in range(len(clcdays)):
        m, d = clcdays[i]['month'], clcdays[i]['day']
        if m == 12 and d == 8:
            clcdays[i]['holiday'] = '腊八'
        elif m == 1 and d == 1:
            clcdays[i]['holiday'] = '春节'
            clcdays[i - 1]['holiday'] = '除夕'
        elif m == 1 and d == 15:
            clcdays[i]['holiday'] = '元宵'
        elif m == 5 and d == 5:
            clcdays[i]['holiday'] = '端午'
        elif m == 7 and d == 7:
            clcdays[i]['holiday'] = '七夕'
        elif m == 7 and d == 15:
            clcdays[i]['holiday'] = '中元'
        elif m == 8 and d == 15:
            clcdays[i]['holiday'] = '中秋'
        elif m == 9 and d == 9:
            clcdays[i]['holiday'] = '重阳'
        elif m == 10 and d == 15:
            clcdays[i]['holiday'] = '下元'

        if clcdays[i]['jieqi'] == '清明':
            clcdays[i - 1]['holiday'] = '寒食'

    return clcdays


def search_lunarcal(year):
    ''' search JieQi and Newmoon, step 1

    Arg:
        year: integer like 2014
    Return:
        a dictionary {ISODATE: Lunar Calendar Date in Chinese}
        start at last LC November
    '''

    global CALCACHE
    if year in CALCACHE:
        return CALCACHE[year]

    clc = find_astro(year)
    clcmonth = mark_lunarcal_month(clc)
    clcdays = mark_lunarcal_day(clcmonth)
    clcdays = mark_holiday(clcdays)

    output = {}
    for d in clcdays:
        output[d['date']] = d

    CALCACHE[year] = output  # cache it for future use
    CALCACHE['cached'].append(year)
    if len(CALCACHE['cached']) > MAXCACHE:
        del CALCACHE[CALCACHE['cached'][0]]
        CALCACHE['cached'].pop(0)

    return output


def cn_lunarcal(year):
    ''' to generate lunar calendar for year, the search should started from
    previous Winter Solstice to next year's Winter Solstic.

    Because there might be a leap month after this Winter Solstic, which can
    only be found by compute Calendar of next year, for example, 2033 has a
    leap 11 that belongs to the next year. Calendar for this and next year are
    computed and combined, then trim to fit into scale of this year.

    '''

    cal0 = search_lunarcal(year)
    cal1 = search_lunarcal(year + 1)
    for k, v in cal1.items():
        cal0[k] = v

    start = jdptime('%s-%s-%s' % (year, 1, 1), '%y-%m-%d')
    end = jdptime('%s-%s-%s' % (year, 12, 31), '%y-%m-%d')
    lc = []
    for jd, day in cal0.items():
        day['date'] = jdftime(jd, '%y-%m-%d', ut=False)
        if jd >= start and jd <= end:
            lc.append((jd, day))

    lc.sort()
    res = [x[1] for x in lc]

    return res


def main():
    a = cn_lunarcal(2033)
    for x in a:
        print(x['date'], x['lunardate'], x['jieqi'], x['holiday'])


if __name__ == "__main__":
    main()