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 Hyndman Rob.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:

• https://pkg.robjhyndman.com/calcal/

• https://github.com/robjhyndman/calcal

• Report bugs at https://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, which currently 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

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 using new_date() for any calendar. Dates can be converted from one calendar to another using as_date(). as_date() also works with the native R Date class and several other classes. When applied to integers, the conversion is from the RD day number (with day 1 being 01-01-01 on the Gregorian calendar).

Usage

as_date(date, calendar)

new_date(..., calendar)

Arguments

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

Value

A vector containing "time_of_day" objects

See Also

time_of_day

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

Value

A babylonian vector object

See Also

cal_babylonian

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 five intercalary 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

Value

A bahai vector object

See Also

cal_bahai, bahai_new_year

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

Value

A vector of dates on the Gregorian calendar

See Also

bahai_date

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 concurrent weeks, 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 on another 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

Value

A balinese vector object

See Also

kajeng_keliwon

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 different locations 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

Value

A chinese vector object

See Also

cal_chinese, chinese_new_year

Examples

chinese <- new_date(
  cycle = 78, year = 42, month = 5, leap_month = FALSE, day = 16:18,
  calendar = cal_chinese
)
chinese
chinese_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

Value

A vector of dates on the Gregorian calendar

See Also

chinese_date

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 on 29 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, and unofficial calendar of Eritrea, and is used by the Ethiopian and Eritrean Orthodox Churches. Both calendars have 13 months, with 12 months of 30 days and a 13th month of 5 or 6 days depending on 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

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 Gregorian dates, and for some other calendars where it makes sense. In particular, day_of_week has been implemented for many calendars that contain the concept of a week. Similarly, day_of_month, day_of_year and days_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

Details

week_of_year() returns the ISO 8601 week number with first_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 may begin in the previous calendar year.

week_of_month() is defined analogously where week 1 of a month is the first week with at least 4 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 of day_of_week(), it returns a character vector of the name of the day of the week, or a numeric vector if numeric = 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

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 original version, used from 1793, was kept in sync with the solar year by setting the first day of Vendemiaire to the autumnal equinox. The second version, proposed in 1795, was a simpler arithmetic 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

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 the relevant 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

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. It was named for Pope Gregory XIII who introduced it in 1582. It is a modification of the Julian calendar which was in use at the time.

Usage

gregorian_date(year = integer(), month = integer(), day = integer())

as_gregorian(date)

Arguments

Value

A gregorian vector object

See Also

cal_gregorian

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 used for Jewish religious holidays. It is a lunisolar calendar comprising months of 29 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 12 or 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

Details

The observational Hebrew calendar ("ohebrew") is the classical calendar where the new month began with the reported observation of the crescent new moon. In this implementation, Haifa is taken as the point of observation.

The Samaritan calendar is similar, but the moment of new moon marking the start of each new month is based on a traditional reckoning of the lunar cycle,

Value

A hebrew vector object

See Also

cal_hebrew, rosh_hashanah

Examples

heb <- new_date(year = 5785, month = 3, day = 2:4, calendar = cal_hebrew)
heb
hebrew_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 the Hindu 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

Value

A vector of dates on the Gregorian calendar

See Also

hindu_lunar_date

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

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 into 7-day weeks and two seasons: Summer and Winter. Summer starts on the first Thursday after April 18th, and Winter 180 days earlier. Ordinary years have 52 weeks with leap years having 53 weeks. The leap week occurs every 5-7 years in midsummer.

Usage

icelandic_date(
  year = integer(),
  season = integer(),
  week = integer(),
  weekday = integer()
)

as_icelandic(date)

Arguments

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 12 lunar months in a year of 354 or 355 days. It is widely used in for Islamic holidays, and in countries where the predominant religion 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

Details

Three variations are implemented here. The standard Islamic calendar is available using as_islamic and islamic_date. The Saudi Islamic calendar uses as_saudi and saudi_date, while the traditional observational Islamic calendar is available using as_oislamic and oislamic_date.

Value

An islamic vector object

See Also

cal_islamic, ramadan

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. Specific dates 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

Value

A vector of dates on the Gregorian calendar

See Also

islamic_date

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 1 is 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 may begin in the previous calendar year.

Usage

iso_date(year = integer(), week = integer(), day = integer())

as_iso(date)

Arguments

Details

More flexible week numbering is possible using Gregorian dates with week_of_year().

Value

An iso vector object

See Also

cal_iso, week_of_year

Examples

iso <- new_date(year = 2025, week = 23, day = 2:4, calendar = cal_iso)
iso
iso_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, and takes its name from Julius Caesar, who introduced it in 46 BC. It is still used as a religious calendar in parts of the Eastern Orthodox Church.

Usage

julian_date(year = integer(), month = integer(), day = integer())

as_julian(date)

Arguments

Value

A julian vector object

See Also

cal_julian

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 of Gregorian years.

Usage

kajeng_keliwon(year)

tumpek(year)

Arguments

Value

A vector of dates on the Gregorian calendar

See Also

balinese_date

Examples

kajeng_keliwon(2025)
tumpek(2025)

Locations

Description

Create a location object. These are used for calculating the timing of astronomical events such as sunrise and sunset.

Usage

location(
  latitude = numeric(),
  longitude = numeric(),
  elevation = numeric(),
  zone = numeric()
)

Arguments

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 degrees means the last quarter.

Usage

lunar_phase(date)

Arguments

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 that has been implemented here.

Usage

mayan_date(
  baktun = integer(),
  katun = integer(),
  tun = integer(),
  uinal = integer(),
  kin = integer()
)

as_mayan(date)

Arguments

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

cal_mayan

Examples

gregorian_date(2012, 12, 10:30) |>
  as_mayan()

Define calendar objects

Description

Generate a calendar object of class "calendar". Examples of calendars produced in this way include cal_chinese, cal_gregorian, cal_hebrew, cal_islamic, and cal_iso.

Usage

new_calendar(
  name,
  short_name,
  granularities,
  validate_granularities,
  format,
  from_rd,
  to_rd
)

cal_babylonian

cal_bahai

cal_balinese

cal_chinese

cal_japanese

cal_korean

cal_vietnamese

cal_coptic

cal_ethiopic

cal_egyptian

cal_armenian

cal_french

cal_afrench

cal_gregorian

cal_hebrew

cal_icelandic

cal_islamic

cal_iso

cal_julian

cal_oislamic

cal_saudi

cal_ohebrew

cal_samaritan

cal_mayan

cal_hindu_lunar

cal_hindu_solar

cal_old_hindu_solar

cal_old_hindu_lunar

cal_persian

cal_apersian

cal_roman

cal_tibetan

Arguments

Value

A calendar object of class "calendar"

Examples

cal_gregorian
tibble::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

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 version of the calendar, using only arithmetic (rather than astronomical) calculations is available as the apersian 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

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 different nomenclature. Rather than use a (year, month, day) triple for each date, it specifies dates using year, month, event, count.

Usage

roman_date(
  year = integer(),
  month = integer(),
  event = integer(),
  count = integer(),
  leap_day = logical()
)

as_roman(date)

Arguments

Value

A roman vector object

See Also

cal_roman

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. The time zone of the location is used as specified in the location object. No adjustments are made for daylight saving.

Usage

sunrise(date, location)

sunset(date, location)

moonset(date, location)

moonrise(date, location)

Arguments

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 the official Phuglugs version of the Kalachakra calendar, which is similar to the Hindu lunisolar calendars.

Usage

tibetan_date(
  year = integer(),
  month = integer(),
  leap_month = logical(),
  day = integer(),
  leap_day = logical()
)

as_tibetan(date)

Arguments

Value

A tibetan_date object

See Also

tibetan_new_year

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. These functions 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

Value

A vector of Gregorian dates corresponding to the Tibetan New Year

See Also

tibetan_date

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

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

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

Value

A vector of dates on the Gregorian calendar

See Also

hebrew_date

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)
)