| Title: | Calendrical Calculations |
| Version: | 1.0.0 |
| Description: | An R implementation of the algorithms described in Reingold and Dershowitz (4th ed., Cambridge University Press, 2018) <doi:10.1017/9781107415058>, allowing conversion between many different calendar systems. Cultural and religious holidays from several calendars can be calculated. |
| License: | Apache License (≥ 2) |
| ByteCompile: | TRUE |
| Encoding: | UTF-8 |
| RoxygenNote: | 7.3.2 |
| Depends: | R (≥ 4.1.0) |
| Imports: | vctrs |
| Suggests: | knitr, rmarkdown, testthat (≥ 3.0.0), tibble |
| Config/testthat/edition: | 3 |
| URL: | https://pkg.robjhyndman.com/calcal/,https://github.com/robjhyndman/calcal |
| VignetteBuilder: | knitr |
| BugReports: | https://github.com/robjhyndman/calcal/issues |
| NeedsCompilation: | no |
| Packaged: | 2025-07-20 01:48:15 UTC; hyndman |
| Author: | Rob Hyndman [aut, cre, cph], Edward Reingold [cph, ctb] (Original Lisp code), Nachum Dershowitz [cph, ctb] (Original Lisp code) |
| Maintainer: | Rob Hyndman <Rob.Hyndman@monash.edu> |
| Repository: | CRAN |
| Date/Publication: | 2025-07-22 10:30:31 UTC |
calcal: Calendrical Calculations
Description
An R implementation of the algorithms described in Reingold and Dershowitz (4th ed., Cambridge University Press, 2018)doi:10.1017/9781107415058, allowing conversion between many different calendar systems. Cultural and religious holidays from several calendars can be calculated.
Author(s)
Maintainer: Rob HyndmanRob.Hyndman@monash.edu (ORCID) [copyright holder]
Other contributors:
Edward Reingold (Original Lisp code) [copyright holder, contributor]
Nachum Dershowitz (Original Lisp code) [copyright holder, contributor]
See Also
Useful links:
Report bugs athttps://github.com/robjhyndman/calcal/issues
Christian Ecclesiastical Holidays
Description
Functions to return Gregorian dates for various Christian ecclesiastical holidays and other special days
Coptic Christmas is celebrated on 29th of Koiak in the Coptic calendar, whichcurrently corresponds to 7 or 8 January in the Gregorian calendar.
Usage
advent(year)christmas(year)orthodox_christmas(year)epiphany(year)easter(year)orthodox_easter(year)pentecost(year)coptic_christmas(year)astronomical_easter(year)Arguments
year | Gregorian year |
Value
A vector of dates on the Gregorian calendar
Examples
tibble::tibble( year = 2025:2030, advent = advent(year), christmas = christmas(year), orthodox_christmas = orthodox_christmas(year), epiphany = epiphany(year), easter = easter(year), orthodox_easter = orthodox_easter(year), pentecost = pentecost(year))Create a new date vector or convert a date vector to a new calendar
Description
New dates can be calculated usingnew_date() for any calendar. Dates can beconverted from one calendar to another usingas_date().as_date() also workswith the native RDate class and several other classes. When applied tointegers, the conversion is from the RD day number (with day 1 being01-01-01 on the Gregorian calendar).
Usage
as_date(date, calendar)new_date(..., calendar)Arguments
date | Date vector on some calendar |
calendar | Target calendar of class "calendar" |
... | Named arguments denoting the granularities required for |
Value
A date vector of class "rdvec" with the specified calendar.
Examples
april2025 <- new_date(year = 2025, month = 4, day = 1:30, calendar = cal_gregorian)as_date(april2025, calendar = cal_iso)Convert to time of day
Description
Convert to time of day
Usage
as_time_of_day(x, ...)Arguments
x | Vector of times |
... | Additional arguments not currently used |
Value
A vector containing "time_of_day" objects
See Also
Examples
as_time_of_day(Sys.time())Babylonian calendar dates
Description
The classical Babylonian calendar was a lunisolar calendar with a fixed 19-year Metonic cycle.
Usage
babylonian_date( year = integer(), month = integer(), leap_month = logical(), day = integer())as_babylonian(date)Arguments
year | Numeric vector of years |
month | Numeric vector of months |
leap_month | Logical vector of leap months |
day | Numeric vector of days |
date | Vector of dates on some calendar. |
Value
A babylonian vector object
See Also
Examples
tibble::tibble( gregorian = gregorian_date(2335, 1, 1:2), babylonian = as_babylonian(gregorian))babylonian_date(2335, 6, FALSE, 1:2)Bahá'í calendar dates
Description
The Bahá'í calendar is a solar calendar used in the Bahá'í faith comprising 18 months, with four or fiveintercalary days each year. The New Year is at the northern Spring equinox,corresponding to 21 March on the Gregorian calendar. Ayyám-i-Há is specified as month 20.
Usage
bahai_date( major = integer(), cycle = integer(), year = integer(), month = integer(), day = integer())as_bahai(date)Arguments
major | A numeric vector of major periods |
cycle | A numeric vector of cycles |
year | A numeric vector of years within the cycles |
month | A numeric vector of months |
day | A numeric vector of days |
date | A numeric vector of dates |
Value
A bahai vector object
See Also
Examples
tibble::tibble( gregorian = gregorian_date(2025, 2, 15) + 0:30, bahai = as_bahai(gregorian))bahai_date(1, 10, 11, 3, 5:7)Bahá'í holidays
Description
Dates are returned as Gregorian dates
Usage
bahai_new_year(year)naw_ruz(year)feast_of_ridvan(year)birth_of_the_bab(year)Arguments
year | The year on the Gregorian calendar |
Value
A vector of dates on the Gregorian calendar
See Also
Examples
tibble::tibble( year = 2025:2030, new_year = bahai_new_year(year), naw_ruz =naw_ruz(year), ridvan = feast_of_ridvan(year), birth_bab = birth_of_the_bab(year))Balinese Pawukon calendar dates
Description
The Balinese calendar repeats every 210 days. It has 10 concurrentweeks, of lengths 1, 2, ..., 10 days. The 210 day cycles are unnumbered,so there is no way to convert a Balinese date into a unique date onanother calendar.
Usage
balinese_date( luang = integer(), dwiwara = integer(), triwara = integer(), caturwara = integer(), pancawara = integer(), sadwara = integer(), saptawara = integer(), asatawara = integer(), sangawara = integer(), dasawara = integer())as_balinese(date)Arguments
luang | A numeric vector |
dwiwara | A numeric vector |
triwara | A numeric vector |
caturwara | A numeric vector |
pancawara | A numeric vector |
sadwara | A numeric vector |
saptawara | A numeric vector |
asatawara | A numeric vector |
sangawara | A numeric vector |
dasawara | A numeric vector |
date | A vector of dates on some calendar. |
Value
A balinese vector object
See Also
Examples
gregorian_date(2025,6,1:10) |> as_balinese()Internal vctrs methods
Description
Internal vctrs methods
Chinese, Japanese, Korean and Vietnamese calendar dates
Description
The traditional Chinese lunisolar calendar uses a 60-year cycle with 12 months per year.The Japanese, Korean and Vietnamese calendars are almost identical, but with differentlocations for determining astronomical positions.
Usage
chinese_date( cycle = integer(), year = integer(), month = integer(), leap_month = logical(), day = integer())japanese_date( cycle = integer(), year = integer(), month = integer(), leap_month = logical(), day = integer())korean_date( year = integer(), month = integer(), leap_month = logical(), day = integer())vietnamese_date( cycle = integer(), year = integer(), month = integer(), leap_month = logical(), day = integer())as_chinese(date)as_japanese(date)as_korean(date)as_vietnamese(date)Arguments
cycle | A numeric vector of cycles |
year | A numeric vector of years within the cycles |
month | A numeric vector of months |
leap_month | A logical vector indicating leap months |
day | A numeric vector of days |
date | A numeric vector of dates |
Value
A chinese vector object
See Also
Examples
chinese <- new_date( cycle = 78, year = 42, month = 5, leap_month = FALSE, day = 16:18, calendar = cal_chinese)chinesechinese_date(78, 42, 5, FALSE, 16:18)as_date(chinese, calendar = cal_gregorian)as_date(Sys.Date(), calendar = cal_chinese)tibble::tibble( gregorian = gregorian_date(2025, 1, 1) + 0:364, chinese = as_chinese(gregorian))as_gregorian(chinese_date(78, 41, 12, FALSE, 3:30))as_chinese(gregorian_date(2025, 1, 1:28))as_chinese("2016-01-01")as_chinese(Sys.Date())Chinese holidays
Description
Dates are returned as Gregorian dates
Usage
chinese_new_year(year)dragon_festival(year)qing_ming(year)Arguments
year | The year on the Gregorian calendar |
Value
A vector of dates on the Gregorian calendar
See Also
Examples
tibble::tibble( year = 2025:2030, cny = chinese_new_year(year), qm = qing_ming(year), dbf = dragon_festival(year))Coptic and Ethoiopic calendar dates
Description
These two calendars are identical apart from the starting point or epoch.The Coptic calendar (also called the Alexandrian calendar) starts on29 August 284 CE in the Julian calendar, while the Ethiopic (or Ethiopian)calendar starts on 29 August 8 CE in the Julian calendar.The Coptic calendar is used by the Coptic Orthodox and Coptic Catholic Churches,while the Ethiopic calendar is the official state calendar of Ethiopia, andunofficial calendar of Eritrea, and isused by the Ethiopian and Eritrean Orthodox Churches. Both calendars have 13months, with 12 months of 30 days and a 13th month of 5 or 6 days dependingon whether it is a leap year. Leap years occur every 4 years.
Usage
coptic_date(year = integer(), month = integer(), day = integer())ethiopic_date(year = integer(), month = integer(), day = integer())as_coptic(date)as_ethiopic(date)Arguments
year | A numeric vector of years |
month | A numeric vector of months |
day | A numeric vector of days |
date | A numeric vector of dates |
Value
A coptic or ethiopic vector object
See Also
cal_coptic,cal_ethiopic,coptic_christmas
Examples
tibble::tibble( gregorian = gregorian_date(2025, 1, 1:31), coptic = as_coptic(gregorian), ethiopic = as_ethiopic(gregorian))coptic_date(1741, 5, 16:18)as_date(Sys.Date(), calendar = cal_ethiopic)as_coptic("2016-01-01")as_ethiopic(Sys.Date())Compute granularities from dates
Description
Compute days, weeks, or months from a vector of dates. These work for Gregoriandates, and for some other calendars where it makes sense. In particular,day_of_weekhas been implemented for many calendars that contain the concept of a week. Similarly,day_of_month,day_of_year anddays_remaining will work for several calendars.
Usage
day_of_week(date, ...)day_of_month(date)day_of_year(date)days_remaining(date)week_of_month(date, first_day = "Monday")week_of_year(date, first_day = "Monday")month_of_year(date)year(date)Arguments
date | A vector of dates |
... | Other arguments used for specific calendars |
first_day | Character denoting first day of the week. Default is |
Details
week_of_year() returns the ISO 8601 week number withfirst_day as Monday.Under this standard, week 1 of a year is defined as the first week with at least 4 days in the year;equivalently, it is the week containing 4 January. There is no week 0; instead week 1 of a year maybegin in the previous calendar year.
week_of_month() is defined analogously where week 1 of a month is the first week with at least4 days in the month; equivalently, it is the week containing the 4th day of the month. There is no week 0;instead week 1 of a month may begin in the previous calendar month.
days_remaining() returns the number of days remaining in the year.
Other functions should be self-explanatory.
Value
A vector of numerical values for the requested granularity. In the case ofday_of_week(), it returns a character vector of the name of the day of the week, or a numeric vector ifnumeric = TRUE is specified.
Examples
april2025 <- gregorian_date(2025, 4, 1:30)day_of_week(april2025)day_of_month(april2025)day_of_year(april2025)days_remaining(april2025)week_of_month(april2025)week_of_year(april2025)month_of_year(april2025)Egyptian and Armenian calendar dates
Description
The ancient Egyptian calendar is a 365-day solar calendar with 12 months of 30 days each, plus a 13th month of 5 days.The Armenian calendar is similar but has a different epoch and month names.
Usage
egyptian_date(year = integer(), month = integer(), day = integer())armenian_date(year = integer(), month = integer(), day = integer())as_egyptian(date)as_armenian(date)Arguments
year | Numeric vector of years |
month | Numeric vector of months |
day | Numeric vector of days |
date | Vector of dates on some calendar |
Value
An egyptian or armenian vector object
Examples
tibble::tibble( gregorian = gregorian_date(2025, 5, 1:10), egyptian = as_egyptian(gregorian), armenian = as_armenian(gregorian))French Revolutionary calendar dates
Description
There are two versions of the French Revolutionary Calendar. The originalversion, used from 1793, was kept in sync with the solar year by setting the first day ofVendemiaire to the autumnal equinox. The second version, proposed in 1795, was a simplerarithmetic calendar, but was never used. We distinguish the two by using "afrench"(for Arithmetic French) for the second form.
Usage
french_date(year = integer(), month = integer(), day = integer())afrench_date(year = integer(), month = integer(), day = integer())as_french(date)as_afrench(date)Arguments
year | year |
month | month |
day | day |
date | A vector of dates on some calendar |
Value
A vector of dates on the French Revolutionary calendar
Examples
french_date(1, 1, 1:15) |> as_gregorian()french_date(1, 1, 1:15) |> day_of_week()Canonical granularities
Description
granularities() will return a character vector of canonical granularity names for therelevant calendar. These are the granularities used to define dates on the calendar.granularity() will return a vector of numerical values for a given canonical granularity.
Usage
granularity_names(calendar)granularity(date, granularity)Arguments
calendar | A calcal object defining a calendar. |
date | A date vector on some calendar |
granularity | A character string indicating the granularity to extract |
Value
A character vector of granularity names or a vector of numerical values for the specified granularity.
See Also
week_of_year for some non-canonical granularities.
Examples
granularity_names(cal_iso)granularity_names(cal_gregorian)date_iso <- new_date(year = 2025, week = 23, day = 2, calendar = cal_iso)granularity(date_iso, "week")date_gregorian <- new_date(year = 2025, month = 1, day = 1, calendar = cal_gregorian)granularity(date_gregorian, "month")Gregorian calendar dates
Description
The Gregorian calendar is the standard calendar used by most of the world. Itwas named for Pope Gregory XIII who introduced it in 1582. It is a modificationof the Julian calendar which was in use at the time.
Usage
gregorian_date(year = integer(), month = integer(), day = integer())as_gregorian(date)Arguments
year | A numeric vector of years |
month | A numeric vector of months |
day | A numeric vector of days |
date | Vector of dates on some calendar |
Value
A gregorian vector object
See Also
Examples
new_date(year = 2025, month = 3, day = 2:4, calendar = cal_gregorian)gregorian_date(2025, 4, 19:30)as_date(Sys.Date(), calendar = cal_gregorian)as_gregorian(Sys.Date())as_gregorian("2016-01-01")tibble::tibble( x = seq(as.Date("2025-01-01"), as.Date("2025-12-31"), by = "day"), y = as_gregorian(x), z = as_date(x, calendar = cal_gregorian))Hebrew calendar dates
Description
The Hebrew (or Jewish) calendar is an official calendar of Israel, and is usedfor Jewish religious holidays. It is a lunisolar calendar comprising months of29 or 30 days, which begin and end at approximately the time of the new moon.An extra lunar month is added every 2 or 3 years, so the calendar has either 12or 13 months per year.
Usage
hebrew_date(year = integer(), month = integer(), day = integer())as_hebrew(date)ohebrew_date(year = integer(), month = integer(), day = integer())as_ohebrew(date)samaritan_date(year = integer(), month = integer(), day = integer())as_samaritan(date)Arguments
year | A numeric vector of years |
month | A numeric vector of months |
day | A numeric vector of days |
date | Vector of dates on some calendar |
Details
The observational Hebrew calendar ("ohebrew") is the classical calendar where thenew month began with the reported observation of the crescent new moon. In thisimplementation, Haifa is taken as the point of observation.
The Samaritan calendar is similar, but the moment of new moon marking the start ofeach new month is based on a traditional reckoning of the lunar cycle,
Value
A hebrew vector object
See Also
Examples
heb <- new_date(year = 5785, month = 3, day = 2:4, calendar = cal_hebrew)hebhebrew_date(5785, 3, 2:4)as_date(heb, calendar = cal_gregorian)as_date(Sys.Date(), calendar = cal_hebrew)tibble::tibble( gregorian = gregorian_date(2025, 1, 1) + 0:364, hebrew = as_date(gregorian, calendar = cal_hebrew),)as_gregorian(hebrew_date(5785, 3, 2:4))as_hebrew(gregorian_date(2025, 1, 1:31))as_hebrew("2016-01-01")as_hebrew(Sys.Date())hebrew_date(5785, 3, 1:10) |> day_of_week()Hindu holidays and special days
Description
Functions to return Gregorian dates for various Hindu holidays based on theHindu calendars.Hindu Lunar New Year is the first day of the lunar month of Caitra (month 1).The Birthday of Rama is on the 8th or 9th day of the first month (Caitra).Diwali is on the new moon day in the month of Kartik (month 8).The Great Night of Shiva is at the end of the 11 month of Magha.Mesha Sankranti is the day when the sun enters the sign of Aries (Mesha).Sacred Wednesdays are the 8th day of the lunar month that falls on a Wednesday.Dates may vary by a day or two due to variations of the lunar calendar and local traditions.
Usage
hindu_lunar_new_year(year)mesha_sankranti(year)diwali(year)shiva(year)rama(year)sacred_wednesdays(year)Arguments
year | A numeric vector of Gregorian years |
Value
A vector of dates on the Gregorian calendar
See Also
Examples
shiva(2025:2026)hindu_lunar_new_year(2025:2026)rama(2025:2026)mesha_sankranti(2025:2026)diwali(2025:2026)sacred_wednesdays(2025:2026)Hindu solar and lunar calendar dates
Description
There are four Hindu calendars implemented: modern Hindu solar and lunar calendars,and the old Hindu solar and lunar calendars.Hindu solar months are 1/12 of a solar year (approximately 30.44 days),while lunar months are based on the lunar cycle (approximately 29.53 days).
Usage
hindu_solar_date(year, month, day)hindu_lunar_date(year, month, leap_month, day, leap_day)as_hindu_solar(date)as_hindu_lunar(date)old_hindu_solar_date(year = integer(), month = integer(), day = integer())old_hindu_lunar_date( year = integer(), month = integer(), leap_month = logical(), day = integer())as_old_hindu_solar(date)as_old_hindu_lunar(date)Arguments
year | A numeric vector of years |
month | A numeric vector of months |
day | A numeric vector of days |
leap_month | A logical vector indicating if year is a leap year |
leap_day | A logical vector indicating if day is a leap day |
date | A date vector on some calendar |
Value
A vector object of Hindu dates.
See Also
cal_hindu_solar,cal_hindu_lunar,cal_old_hindu_solar,cal_old_hindu_lunar,diwali
Examples
gregorian_date(2025, 1, 1:31) |> as_hindu_solar()gregorian_date(2025, 1, 1:31) |> as_hindu_lunar()Icelandic calendar dates
Description
The Icelandic calendar, still in use in Iceland, divides times into7-day weeks and two seasons: Summer and Winter. Summer starts on the firstThursday after April 18th, and Winter 180 days earlier. Ordinary years have52 weeks with leap years having 53 weeks. The leap week occurs every 5-7years in midsummer.
Usage
icelandic_date( year = integer(), season = integer(), week = integer(), weekday = integer())as_icelandic(date)Arguments
year | A numeric vector of years |
season | A numeric vector of seasons (1 = Summer, 2 = Winter) |
week | A numeric vector of weeks within the season (1 to 28) |
weekday | A number vector containing day of week (0 = Sunday, 1 = Monday,..., 6 = Saturday)) |
date | A numeric vector of dates |
Value
An icelandic vector object
Examples
gregorian_date(2025, 4, 20:30) |> as_icelandic()icelandic_date(2025, 1, 6, 0:6) |> day_of_week()Islamic calendar dates
Description
The Islamic (or Hijri) calendar is a lunar calendar comprising 12lunar months in a year of 354 or 355 days. It is widely used infor Islamic holidays, and in countries where the predominantreligion is Islam.
Usage
islamic_date(year = integer(), month = integer(), day = integer())as_islamic(date)oislamic_date(year = integer(), month = integer(), day = integer())as_oislamic(date)saudi_date(year = integer(), month = integer(), day = integer())as_saudi(date)Arguments
year | A numeric vector of years |
month | A numeric vector of months |
day | A numeric vector of days |
date | Vector of dates on some calendar |
Details
Three variations are implemented here. The standard Islamic calendaris available usingas_islamic andislamic_date. The Saudi Islamic calendarusesas_saudi andsaudi_date, while the traditional observationalIslamic calendar is available usingas_oislamic andoislamic_date.
Value
An islamic vector object
See Also
Examples
islamic_date(2025, 5, 1:30)as_islamic("2016-01-01")as_islamic(Sys.Date())tibble::tibble( x = seq(as.Date("2025-01-01"), as.Date("2025-12-31"), by = "day"), y = as_islamic(x))islamic_date(2025, 5, 1:10) |> day_of_week()islamic_date(2025, 4, 19:30)Islamic holidays
Description
Functions to return Gregorian dates for various Islamic holidays. Specificdates can vary slightly based on moon sightings in different regions.
Usage
islamic_new_year(year)mawlid(year)ramadan(year)eid_al_fitr(year)eid_al_adha(year)Arguments
year | A numeric vector of Gregorian years |
Value
A vector of dates on the Gregorian calendar
See Also
Examples
tibble::tibble( year = 2025:2029, `New year` = islamic_new_year(year), Mawlid = mawlid(year), Ramadan = ramadan(year), `Eid al-Fitr` = eid_al_fitr(year), `Eid al-Adha` = eid_al_adha(year))ramadan(2030)ISO calendar dates
Description
In ISO 8601 date objects, weeks are defined as starting on Mondays. Week 1is the first week with at least 4 days in the year. Equivalently, it is the weekcontaining 4 January. There is no week 0; instead week 1 of a year may begin inthe previous calendar year.
Usage
iso_date(year = integer(), week = integer(), day = integer())as_iso(date)Arguments
year | A numeric vector of years |
week | A numeric vector of weeks |
day | A numeric vector of days |
date | Vector of dates on some calendar |
Details
More flexible week numbering is possible using Gregorian dates withweek_of_year().
Value
An iso vector object
See Also
Examples
iso <- new_date(year = 2025, week = 23, day = 2:4, calendar = cal_iso)isoiso_date(2025, 23, 2:4)as_gregorian(iso_date(2025, 23, 2:4))as_iso(gregorian_date(2025, 1, 1:31))as_iso("2016-01-01")as_iso(Sys.Date())tibble::tibble( x = seq(as.Date("2025-01-01"), as.Date("2025-12-31"), by = "day"), y = as_iso(x))Julian calendar dates
Description
The Julian calendar is the calendar used by the Roman Empire, andtakes its name from Julius Caesar, who introduced it in 46 BC. Itis still used as a religious calendar in parts of the EasternOrthodox Church.
Usage
julian_date(year = integer(), month = integer(), day = integer())as_julian(date)Arguments
year | A numeric vector of years |
month | A numeric vector of months |
day | A numeric vector of days |
date | Vector of dates on some calendar |
Value
A julian vector object
See Also
Examples
as_date("2016-01-01", calendar = cal_julian)as_date(Sys.Date(), calendar = cal_julian)tibble::tibble( x = seq(as.Date("2025-01-01"), as.Date("2025-12-31"), by = "day"), y = as_date(x, calendar = cal_gregorian), z = as_date(x, calendar = cal_julian))new_date(year = 2025, month = 4, day = 19:30, calendar = cal_julian)julian_date(2025, 4, 19:30)as_julian("2016-01-01")as_julian(Sys.Date())tibble::tibble( x = seq(as.Date("2025-01-01"), as.Date("2025-12-31"), by = "day"), y = as_julian(x))Balinese special days
Description
Find all occurrences of Kajeng Keliwon and Tumpek in a vector ofGregorian years.
Usage
kajeng_keliwon(year)tumpek(year)Arguments
year | A numeric vector of Gregorian years |
Value
A vector of dates on the Gregorian calendar
See Also
Examples
kajeng_keliwon(2025)tumpek(2025)Locations
Description
Create a location object. These are used for calculating the timing ofastronomical events such as sunrise and sunset.
Usage
location( latitude = numeric(), longitude = numeric(), elevation = numeric(), zone = numeric())Arguments
latitude | A numeric vector of latitudes |
longitude | A numeric vector of longitudes |
elevation | A numeric vector of elevations above sea level (in metres) |
zone | A numeric vector of time zones (in hours, relative to UTC) |
Value
A location vector object
Examples
melbourne <- location(-37.8136, 144.9631, 31, 10)sunrise("2025-01-01", melbourne)Lunar phase at date
Description
Lunar phase at date, as an angle in degrees. An angle of 0 means a new moon,90 degrees means the first quarter, 180 means a full moon, and 270 degreesmeans the last quarter.
Usage
lunar_phase(date)Arguments
date | Date vector |
Value
A numeric vector of angles in degrees representing the lunar phase at the given dates.
Examples
april2025 <- gregorian_date(2025, 4, 1:30)lunar_phase(april2025)Mayan calendar dates
Description
There are three Mayan calendars: the famous "long count" calendar, the "Haab" calendar, and the "Tzolkin" calendar.Of these, only the long count calendar can be converted to and from other calendars, so it is the only one thathas been implemented here.
Usage
mayan_date( baktun = integer(), katun = integer(), tun = integer(), uinal = integer(), kin = integer())as_mayan(date)Arguments
baktun | Numeric vector |
katun | Numeric vector |
tun | Numeric vector |
uinal | Numeric vector |
kin | Numeric vector |
date | Vector of dates on some calendar |
Details
The Mayan long count calendar is a vigesimal (base-20) calendar with five components: kin (1 day), uinal (20 kin), tun (18 uinal), katun (20 tun), and baktun (20 katun). So the full cycle repeats every 20x18x20x20 = 144,000 days (approximately 394 years).
Value
A mayan vector object
See Also
Examples
gregorian_date(2012, 12, 10:30) |> as_mayan()Define calendar objects
Description
Generate a calendar object of class "calendar". Examples of calendarsproduced in this way includecal_chinese,cal_gregorian,cal_hebrew,cal_islamic,andcal_iso.
Usage
new_calendar( name, short_name, granularities, validate_granularities, format, from_rd, to_rd)cal_babyloniancal_bahaical_balinesecal_chinesecal_japanesecal_koreancal_vietnamesecal_copticcal_ethiopiccal_egyptiancal_armeniancal_frenchcal_afrenchcal_gregoriancal_hebrewcal_icelandiccal_islamiccal_isocal_juliancal_oislamiccal_saudical_ohebrewcal_samaritancal_mayancal_hindu_lunarcal_hindu_solarcal_old_hindu_solarcal_old_hindu_lunarcal_persiancal_apersiancal_romancal_tibetanArguments
name | Name of calendar |
short_name | Short name of calendar |
granularities | Character vector with names of granularities of calendar(e.g., for the Gregorian calendar, the granularities are |
validate_granularities | Function to check granularities are valid (e.g.,Gregorian months should be between 1 and 12). |
format | Function to specify date format as a character string. |
from_rd | Function to convert from RD to calendar date. |
to_rd | Function to convert from calendar date to RD. |
Value
A calendar object of class "calendar"
Examples
cal_gregoriantibble::tibble( x = new_date(year = 2025, month = 5, day = 1:31, calendar = cal_gregorian), y = as_date(x, calendar = cal_islamic))Full moons and new moons in Gregorian years
Description
Calculate all the near-full or near-new moons in a vector of Gregorian years
Usage
new_moons(year)full_moons(year)Arguments
year | A vector of Gregorian years |
Value
A vector of Gregorian dates representing the full moons or new moons in the given years.
A vector of dates
Examples
full_moons(2025)new_moons(2025)Persian dates
Description
The modern Persian calendar was adopted in 1925 in Iran and in 1957 in Afghanistan. An alternative versionof the calendar, using only arithmetic (rather than astronomical) calculations is available as theapersian calendar.
Usage
persian_date(year = integer(), month = integer(), day = integer())apersian_date(year = integer(), month = integer(), day = integer())as_persian(date)as_apersian(date)Arguments
year | Numeric vector of years |
month | Numeric vector of months |
day | Numeric vector of days |
date | Vector of dates on some calendar |
Value
A persian vector object
Examples
gregorian_date(2025,5,1:20) |> as_persian()Roman calendar dates
Description
The Roman calendar (as defined here) is the same as the Julian calendar but with differentnomenclature. Rather than use a (year, month, day) triple for each date, itspecifies dates using year, month, event, count.
Usage
roman_date( year = integer(), month = integer(), event = integer(), count = integer(), leap_day = logical())as_roman(date)Arguments
year | A numeric vector of years |
month | A numeric vector of months |
event | A numeric vector of events: 1 = Kalends, 2 = Nones, 3 = Ides |
count | A numeric vector of counts |
leap_day | A logical vector indicating if day is a leap day |
date | Vector of dates on some calendar |
Value
A roman vector object
See Also
Examples
roman_date(66, 4, 1, 1, FALSE)new_date(year = 66, month = 4, event = 1, count = 1, leap_day = FALSE, calendar = cal_roman)as_roman("2016-01-01")tibble::tibble( x = seq(as.Date("2025-01-01"), as.Date("2025-12-31"), by = "day"), y = as_roman(x))Sun and moon rise and set given a date and location
Description
Calculate the time of sunrise, sunset, moonrise and moonset at a specific location and date. Thetime zone of the location is used as specified in thelocation object. No adjustments are made fordaylight saving.
Usage
sunrise(date, location)sunset(date, location)moonset(date, location)moonrise(date, location)Arguments
date | Vector of dates on some calendar. |
location | Vector of locations of class "location", usually the output from the |
Value
Time of sunrise
Examples
melbourne <- location(-37.8136, 144.9631, 31, 10)sydney <- location(-33.8688, 151.2093, 3, 10)sunrise(gregorian_date(2025, 1, 1), c(melbourne, sydney))sunset(gregorian_date(2025, 1, 1), c(melbourne, sydney))moonrise(gregorian_date(2025, 1, 1), c(melbourne, sydney))moonset(gregorian_date(2025, 1, 1), c(melbourne, sydney))Tibetan calendar dates
Description
There are several Tibetan calendars. These functions implement theofficial Phuglugs version of the Kalachakra calendar, which is similarto the Hindu lunisolar calendars.
Usage
tibetan_date( year = integer(), month = integer(), leap_month = logical(), day = integer(), leap_day = logical())as_tibetan(date)Arguments
year | A numeric vector of years |
month | A numeric vector of months |
leap_month | A logical vector of leap months |
day | A numeric vector of days |
leap_day | A logical vector of leap days |
date | A vector of dates on some calendar |
Value
Atibetan_date object
See Also
Examples
gregorian_date(2025,6,1:10) |> as_tibetan()Tibetan holidays
Description
The Tibetan New Year occurs on the first day of the Tibetan calendar. Thesefunctions calculate the date given either a Gregorian year or a Tibetan year.Both return a Gregorian date.
Usage
tibetan_new_year(year)losar(t_year)Arguments
year | A vector of Gregorian years |
t_year | A vector of Tibetan years |
Value
A vector of Gregorian dates corresponding to the Tibetan New Year
See Also
Examples
tibetan_new_year(2025:2028)losar(2152:2154)Time of day
Description
Create a time object
Usage
time_of_day(hour = integer(), minute = integer(), second = numeric())Arguments
hour | A numeric vector of hours |
minute | A numeric vector of minutes |
second | A numeric vector of seconds |
Value
A time_of_day vector object, stored as a vctrs record containing hours, minutes and seconds.
US Holidays
Description
Functions to return Gregorian dates for US holidays and other special days
Usage
us_memorial_day(year)us_independence_day(year)us_labor_day(year)us_election_day(year)us_daylight_saving_start(year)us_daylight_saving_end(year)unlucky_fridays(year)Arguments
year | Gregorian year |
Value
A vector of Gregorian dates corresponding to the US holidays or special days.
Examples
us_memorial_day(2025)us_independence_day(2025)us_labor_day(2025)us_election_day(2025)us_daylight_saving_start(2025)us_daylight_saving_end(2025)unlucky_fridays(2025)Jewish Holidays
Description
Functions to return Gregorian dates for various Jewish holidays
Usage
yom_kippur(year)passover(year)purim(year)ta_anit_esther(year)tishah_be_av(year)hanukkah(year)rosh_hashanah(year)sukkot(year)shavuot(year)Arguments
year | A numeric vector of Gregorian years |
Value
A vector of dates on the Gregorian calendar
See Also
Examples
tibble::tibble( year = 2025:2030, ta_anit_esther = ta_anit_esther(year), purim = purim(year), passover = passover(year), shavuot = shavuot(year), tishah_be_av = tishah_be_av(year), rosh_hashanah = rosh_hashanah(year), yom_kippur = yom_kippur(year), sukkot = sukkot(year), hanukkah = hanukkah(year))