The `"yearqtr"`

class is used to represent quarterly data. Internally it holds
the data as year plus 0 for Quarter 1, 1/4 for Quarter 2
and so on in order that its internal representation is the same as
`ts`

class with `frequency = 4`

. If `x`

is not in this
format it is rounded via `floor(4*x + .0001)/4`

.

`as.yearqtr.character`

uses a default format of `"%Y Q%q"`

,
`"%Y q%q"`

or `"%Y-%q"`

according to whichever matches.
`%q`

accepts the numbers 1-4 (possibly with leading zeros). Due to
this `%q`

does not match to single digits only and consequently
formats such as `as.yearqtr("Q12000", "Q%q%Y")`

are ambiguous and
do not work (i.e., result in `NA`

).

There are coercion methods available for various classes including:
default coercion to `"yearqtr"`

(which coerces to `"numeric"`

first)
and coercion from `"yearqtr"`

to `"Date"`

(see below), `"POSIXct"`

,
`"POSIXlt"`

, `"numeric"`

, `"character"`

and `"jul"`

.
The last one is from the `frame`

package on CRAN.

There is an `is.numeric`

method which returns `FALSE`

.

There is also a `date`

method for `as.yearqtr`

usable with objects
created with package `date`

.

`Sys.yearqtr()`

returns the current year/month and methods for
`min`

, `max`

and `range`

are defined (by defining
a method for `Summary`

).

A `yearqtr`

`mean`

method is also defined.

Certain methods support a `frac`

argument. See `yearmon`

.