# yearqtr

##### An Index Class for Quarterly Data

`"yearqtr"`

is a class for representing quarterly data.

- Keywords
- ts

##### Usage

```
yearqtr(x)
as.yearqtr(x, ...)
## S3 method for class 'yearqtr':
format(x, format = "\%Y Q\%q", \dots)
```

##### Arguments

- x
- for
`yearqtr`

a numeric (interpreted as beingin years ). For`as.yearqtr`

another date class object. For the`"yearqtr"`

method of`format`

an object of class`"yearqtr"`

- format
- character string specifying format.
`"%C"`

,`"%Y"`

,`"%y"`

and`"%q"`

, if present, are replaced with the century, year, last two digits of the year, and quarter (i.e. a number between 1 and 4), respect - ...
- other arguments. Currently not used.

##### Details

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).
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`

.

##### Value

`yearqtr`

and`as.yearqtr`

return the first argument converted to class`yearqtr`

. The`format`

method returns a character string representation of its argument first argument.

##### See Also

##### Examples

```
x <- as.yearqtr(2000 + seq(0, 7)/4)
x
format(x, "%Y Quarter %q")
as.yearqtr("2001 Q2")
as.yearqtr("2001 q2") # same
as.yearqtr("2001-2") # same
# returned Date is the fraction of the way through
# the period given by frac (= 0 by default)
dd <- as.Date(x)
format.yearqtr(dd)
as.Date(x, frac = 1)
as.POSIXct(x)
zz <- zoo(rnorm(8), x, frequency = 4)
zz
as.ts(zz)
```

*Documentation reproduced from package zoo, version 1.7-9, License: GPL-2*