In jalilian/jalcal: Convert Between Jalaali (Persian or Solar Hijri) and Gregorian Calendar Dates

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jalcal: an R package to convert Jalaali and Gregorian calendar dates

Overview

The Persian or Jalaali calendar, also called the Solar Hijri or Hijri Shamsi calendar, is a 12-month system.

• It begins its count from the Hijra, which is July 19, 622 AD in the standard Gregorian calendar.

• The Persian New Year begins on Nowruz, the spring equinox. This means the start of the year is timed with the start of spring, as determined by astronomical observations.

• The first six months have 31 days each, the next five have 30 days, and the last month has 29 days in common years and 30 days in leap years. Each season consists of three consecutive months.

• The exact leap year determination also relies on the vernal equinox date and time. The calculations and conversions in this package are based on the work by Kazimierz M. Borkowski (1996) who used an analytical model of Earth's motion to calculate equinoxes from AD 550 to 3800 and identify leap years based on Tehran time.

• The Persian calendar is the official calandar in Iran and Afghanistan and is also used in parts of Tajikistan and Kurdistan, particularly among Persian- and Kurdish-speaking communities.

Borkowski, K. M. (1996). The Persian calendar for 3000 years. Earth, Moon, and Planets, 74, 223–230. doi:10.1007/BF00055188

Installation

To install the development version of jalcal from GitHub, use the remotes package:

# Install remotes if not already installed
install.packages("remotes")

# Install getsat from GitHub
remotes::install_github("jalilian/jalcal")

To install the package from CRAN, use the install.packages command:

# install.packages('jalcal')

Example 1: Convert Jalaali dates to Gregorian dates

To convert Jalaali dates (e.g., 1403-12-30 and 1404-01-01) to Gregorian dates, use:

library("jalcal")
dates <- jal2greg(year=c(1403, 1404), month=c(12, 1), day=c(30, 1))
print(dates)

Example 2: Convert Gregorian dates to Jalaali dates

To convert Gregorian dates to Jalaali dates, use:

set.seed(14040101)
gdates <- sample(seq.Date(from = as.Date("561-01-01"), 
                                to = as.Date("3177-12-31"), by = "day"), 
                       size = 100)
jdates <- greg2jal(gdates)
cbind(gdates, jdates)

jalilian/jalcal documentation built on April 17, 2025, 2:57 p.m.