Months: Temporal's PlainYearMonth — plain_year

A plain_year_month() is a month of a year in the ISO 8601 calendar, stored as an integer count of months since January 1970. The constructor is Temporal.PlainYearMonth and Temporal.PlainYearMonth.from() in one: it reads fields, strings or a plain_date() or plain_date_time().

Usage

plain_year_month(
  year,
  month = NULL,
  ...,
  month_code = NULL,
  overflow = "constrain"
)

plain_year_month_compare(x, y)

Arguments

year: The year, or a string in ISO 8601 form ("2026-03", "202603", or a full date or date-time whose day and time are ignored), or a plain_year_month(), plain_date() or plain_date_time() to convert.
month: The month (1 to 12), when year is a number. May be replaced by month_code.
...: Must be empty.
month_code: The month as "M01" to "M12", instead of month.
overflow: "constrain" (the default) clamps month to 1 to 12, "reject" raises a zutempo_range_error.
x, y: plain_year_month() values or strings, for plain_year_month_compare().

Value

A plain_year_month() vector; plain_year_month_compare() returns an integer vector of -1, 0 and 1.

Details

Months run from -271821-04 to +275760-09, every month that holds a representable plain_date().

Members

Every member of Temporal.PlainYearMonth in the pinned specification (inst/spec/PINS) and the R function that implements it:

Temporal	R
`new Temporal.PlainYearMonth()`	`plain_year_month()`
`Temporal.PlainYearMonth.from()`	`plain_year_month()`
`Temporal.PlainYearMonth.compare()`	`plain_year_month_compare()`
`.calendarId`	`calendar_id()`
`.era`	`era()`
`.eraYear`	`era_year()`
`.year`	`year()`
`.month`	`month()`
`.monthCode`	`month_code()`
`.daysInYear`	`days_in_year()`
`.daysInMonth`	`days_in_month()`
`.monthsInYear`	`months_in_year()`
`.inLeapYear`	`in_leap_year()`
`.with()`	`temporal_with()`
`.add()`	`temporal_add()`
`.subtract()`	`temporal_subtract()`
`.until()`	`temporal_until()`
`.since()`	`temporal_since()`
`.equals()`	`temporal_equals()`
`.toString()`	`temporal_to_string()`
`.toLocaleString()`	none: ECMA-402 (locale formatting) is out of scope
`.toJSON()`	none: format() covers it
`.valueOf()`	none: throws in JavaScript; no R counterpart
`.toPlainDate()`	`temporal_to_plain_date()`

Examples

plain_year_month("2026-03")
#> <zutempo_plain_year_month[1]>
#> [1] 2026-03
plain_year_month(2026, 3)
#> <zutempo_plain_year_month[1]>
#> [1] 2026-03
plain_year_month(plain_date("2026-03-15"))
#> <zutempo_plain_year_month[1]>
#> [1] 2026-03
temporal_to_plain_date(plain_year_month("2026-02"), day = 31)
#> <zutempo_plain_date[1]>
#> [1] 2026-02-28
plain_year_month_compare("2026-02", "2026-03")
#> [1] -1