An Index Class for Quarterly Data
"yearqtr" is a class for representing quarterly data.
yearqtr(x) as.yearqtr(x, ...) ## S3 method for class 'yearqtr': format(x, format = "\%Y Q\%q", \dots)
yearqtra numeric (interpreted as being
in years). For
as.yearqtranother date class object. For the
formatan object of class
- character string specifying format.
"%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.
"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" 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
and coercion from
"Date" (see below),
The last one is from the
frame package on CRAN.
There is an
is.numeric method which returns
There is also a
date method for
as.yearqtr usable with objects
created with package
Sys.yearqtr() returns the current year/month and methods for
range are defined (by defining
a method for
mean method is also defined.
Certain methods support a
frac argument. See
as.yearqtrreturn the first argument converted to class
formatmethod returns a character string representation of its argument first argument.
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)