chron (version 2.2-4)

day.of.week: Convert between Julian and Calendar Dates

Description

Utility functions to convert between Julian dates (numbers of days since an origin, by default 1970-01-01) and calendar dates given by year, month, and day within the month.

Usage

julian(m, d, y, origin = c(month = 1, day = 1, year = 1970))
month.day.year(jul, origin = c(month = 1, day = 1, year = 1970))
leap.year(y)
day.of.week(month, day, year)

Arguments

m

vector of month numbers.

d

vector of day numbers.

y

vector of years.

jul

vector of Julian Dates, i.e., number of days since origin.

origin

vector specifying the origin as month, day, and year. If missing, it defaults to getOption("chron.origin") if this is non-null, otherwise c(month = 1, day = 1, year = 1970).

Value

• A vector of Julian dates (number of days since origin) when julian() is called, or a list with members month, day, year corresponding to the input Julian dates if month.day.year() is called. leap.year() returns a logical vector indicating whether the corresponding year is a leap year. day.of.week() returns a number between 0 and 6 to specify day of the week--0 refers to Sunday.

  These functions were taken from Becker, Chambers, and Wilks (1988), and were slightly modified to take chron and dates objects; some also take the extra argument origin.

See Also

chron, dates, times

Examples

julian(1, 1, 1970)
# [1] 0
unlist(month.day.year(0))
# month   day  year 
#     1     1  1970

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