`calendar_leap_year()`

detects if the calendar year is a leap year - i.e.
does it contain one or more extra components than other years?

A particular year is a leap year if:

`year_month_day()`

: February has 29 days.`year_month_weekday()`

: February has a weekday that occurs 5 times.`year_week_day()`

: There are 53 weeks in the year, resulting in 371 days in the year.`iso_year_week_day()`

: There are 53 weeks in the year, resulting in 371 days in the year.`year_quarter_day()`

: One of the quarters has 1 more day than normal (the quarter with an extra day depends on the`start`

used, but will always be the same for a particular`start`

). This aligns with Gregorian leap years for all`start`

s except February, in which case the leap year is always 1 year after the Gregorian leap year.`year_day()`

: There are 366 days in the year.

## Value

A logical vector the same size as `x`

. Returns `TRUE`

if in a leap
year, `FALSE`

if not in a leap year, and `NA`

if `x`

is `NA`

.

## Examples

```
x <- year_month_day(c(2019:2024, NA))
calendar_leap_year(x)
#> [1] FALSE TRUE FALSE FALSE FALSE TRUE NA
# For year-quarter-day, the leap year typically aligns with the Gregorian
# leap year, unless the `start` is February, in which case the leap year is
# always 1 year after the Gregorian leap year
x <- year_quarter_day(2020:2021, start = clock_months$january)
calendar_leap_year(x)
#> [1] TRUE FALSE
x <- year_quarter_day(2020:2021, start = clock_months$february)
calendar_leap_year(x)
#> [1] FALSE TRUE
# With a January start, 2020 has the extra day
get_day(year_quarter_day(2020, 1:4, "last", start = clock_months$january))
#> [1] 91 91 92 92
get_day(year_quarter_day(2021, 1:4, "last", start = clock_months$january))
#> [1] 90 91 92 92
get_day(year_quarter_day(2022, 1:4, "last", start = clock_months$january))
#> [1] 90 91 92 92
# With a February start, 2021 has the extra day
get_day(year_quarter_day(2020, 1:4, "last", start = clock_months$february))
#> [1] 89 92 92 92
get_day(year_quarter_day(2021, 1:4, "last", start = clock_months$february))
#> [1] 90 92 92 92
get_day(year_quarter_day(2022, 1:4, "last", start = clock_months$february))
#> [1] 89 92 92 92
```