zoo (version 1.5-0)

yearqtr: An Index Class for Quarterly Data

Description

"yearqtr" is a class for representing quarterly data.

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 being in 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.

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.

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".

See Also

yearmon, zoo, zooreg, ts, code{strptime}.

Examples

Run this code
x <- 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)

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