Description Usage Arguments Value Examples

The methods in this section facilitate
year-, month-, day-, and quarter-number extraction from objects that represent dates,
as well as
`mondate`

construction
using the year, month, and day numbers of the date
(as those numbers would be seen in the character representation of the date,
i.e.., "January" = 1 and the first day of a month = 1).

1 2 3 4 5 6 7 8 9 |

`x` |
an object of class |

`m` |
the month: 1, ..., 12.
If "missing" and |

`d` |
the day: 1, ..., 31, depending on the month.
If "missing" in the case of |

`y` |
the four-digit year. |

`...` |
For |

`year`

returns the year `numeric`

(e.g., 2000).

`month`

returns the month `numeric`

1, ..., 12.

`day`

returns the `numeric`

day of the month.

`quarter`

returns the `numeric`

calendar quarter of the year:
1 for January - March, 2 for April - June, etc.

`ymd`

returns a matrix with the number of rows equal to the
length of `x`

,
with appropriately-named
columns 1 through 3 holding the `year`

,
`month`

, and `day`

, respectively
and with "rownames" equal to `names(x)`

.

`mondate.mdy`

and `mondate.ymd`

return `mondate`

s with the given
month, day, and year.
Arguments `m`

, `d`

, and `y`

may have length > 1;
the usual recycling rules apply.

The `mondate.ymd`

function has a bit more functionality.
If `d`

is "missing" in a call to `mondate.ymd`

then the date
returned will be the last day of month `m`

in year `y`

.
If `m`

is also missing,
then the date returned will be the last day of the year.
If any of `y`

, `m`

, or `d`

are `NA`

the result will be an all-`NA`

vector.
And if `y=+-Inf`

then the result will be an "infinite" mondate vector,
overriding other rules included herein.
The length of a vector result is determined
using the usual recycling rules
as though a valid, finite scalar had been inserted instead of
`NA`

or `+-Inf`

.
See the **Examples** section.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 | ```
M <- mondate.mdy(6,30,2008)
year(M) # 2008
month(M) # 6
day(M) # 30
mondate.ymd(2008,6,30) # ditto
mondate.ymd(2008,6) # ditto; 'day' argument is "missing" so
# returns the last day of the month
mondate.ymd(2008,1:12) # all month-ends of 2008, a leapyear
# year-ends 2001 through 2013, displaying only the 4-digit year when shown
mondate.ymd(2001:2013, displayFormat = "%Y")
mondate.ymd(2010:2012, NA) # NA mondate vector of length 3
mondate.ymd(Inf,11,31) # An infinite mondate even though only 30 days in
# November
x <- mondate.ymd(2013, 1:12) # month-ends in 2013
# Give x some shape
dim(x) <- 3:4
dimnames(x) <- list(A = letters[1:3], B = LETTERS[1:4])
# Return the quarter numbers in an array with the same shape and dimnames
quarter(x)
``` |

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