Wrote quarter accessor, which returns a date's quarter as a number.

DESCRIPTION

@@ -67,3 +67,4 @@ Collate:
     'guess.r'
     'stamp.r'
     'ops-%m+%.r'
+    'accessors-quarter.r'

NAMESPACE

@@ -163,6 +163,7 @@ export(pretty.sec)
 export(pretty.unit)
 export(pretty.year)
 export(pretty_dates)
+export(quarter)
 export(reclass_date)
 export(reclass_timespan)
 export(rollback)

R/accessors-quarter.r

@@ -0,0 +1,36 @@
+#' @include accessors-month.r
+NULL
+
+#' Get the fiscal quarter of a date-time.
+#'
+#' Fiscal quarters are a way of dividing the year into fourths. The first quarter (Q1) 
+#' comprises January, February and March; the second quarter (Q2) comprises April, May, 
+#' June; the third quarter (Q3) comprises July, August, September; the fourth quarter (Q4)
+#' October, November, December.
+#'
+#' @param x a date-time object of class POSIXct, POSIXlt, Date, chron, yearmon, yearqtr, zoo, 
+#' zooreg, timeDate, xts, its, ti, jul, timeSeries, fts or anything else that can be converted 
+#' with as.POSIXlt
+#' @keywords utilities manip chron methods
+#' @return numeric the fiscal quarter that the date-time occurs in
+#' @examples
+#' x <- ymd(c("2012-03-26", "2012-05-04", "2012-09-23", "2012-12-31"))
+#' # 1 2 3 4
+#' @export
+quarter <- function(x) {
+  m <- month(x)
+  quarters <- c("1" = 1, 
+                "2" = 1, 
+                "3" = 1, 
+                "4" = 2, 
+                "5" = 2, 
+                "6" = 2, 
+                "7" = 3, 
+                "8" = 3, 
+                "9" = 3, 
+                "10" = 4, 
+                "11" = 4, 
+                "12" = 4)
+  unname(quarters[m])
+}
+

man/quarter.Rd

@@ -0,0 +1,32 @@
+\name{quarter}
+\alias{quarter}
+\title{Get the fiscal quarter of a date-time.}
+\usage{
+  quarter(x)
+}
+\arguments{
+  \item{x}{a date-time object of class POSIXct, POSIXlt,
+  Date, chron, yearmon, yearqtr, zoo, zooreg, timeDate,
+  xts, its, ti, jul, timeSeries, fts or anything else that
+  can be converted with as.POSIXlt}
+}
+\value{
+  numeric the fiscal quarter that the date-time occurs in
+}
+\description{
+  Fiscal quarters are a way of dividing the year into
+  fourths. The first quarter (Q1) comprises January,
+  February and March; the second quarter (Q2) comprises
+  April, May, June; the third quarter (Q3) comprises July,
+  August, September; the fourth quarter (Q4) October,
+  November, December.
+}
+\examples{
+x <- ymd(c("2012-03-26", "2012-05-04", "2012-09-23", "2012-12-31"))
+# 1 2 3 4
+}
+\keyword{chron}
+\keyword{manip}
+\keyword{methods}
+\keyword{utilities}
+