TimeWarp (version 1.0.15)

TimeWarp-package: Date sequence and manipulation with business days and holidays.

Description

A package for manipulating vectors of class Date. Support for other vectors and classes may be added in the future.

The general idea with the behavior of functions from this package is that they should return an object of the same class as they are given, e.g., dateWarp() applied to a vector of dates in character format should return a vector of dates in character format, and dateWarp() applied to a Date class vector should return a Date class vector.

This functionality is currently implemented for Date, character, POSIXct and POSIXlt classes. For other classes, functions from this package will currently return a Date vector, but that may change as other classes are added.

Version 1.0 of TimeWarp does not handle times on POSIXct and POSIXlt: the functions in TimeWarp will return the same type of object stripped of times. This may change in the future.

See Also

dateWarp, dateAlign, dateSeq, dateMatch, and holidays.

The Holidays package loads a database of holidays into the TimeWarp package.

pitfalls describes some pitfalls with date class conversions.

On the use of Date, chron and POSIXt classes: Gabor Grothendieck and Thomas Petzoldt. R help desk: Date and time classes in R. http://cran.r-project.org/doc/Rnews/Rnews_2004-1.pdf (Has a helpful table of how to accomplish various tasks with the different classes.)

On the creation and use of the POSIXt classes (POSIXct and POSIXlt): Brian D. Ripley and Kurt Hornik. Date-time classes. http://cran.r-project.org/doc/Rnews/Rnews_2001-2.pdf

Examples

# NOT RUN {
library(Holidays)
# View counts of registered holidays by year
sapply(as.character(1998:2012), function(y)
       sapply(allHolidays(), function(h) length(holidays(y, h, silent=TRUE))))

# Find US option expiration dates in 2011 (The pricing day, usually a Friday)

# Technically speaking, standardized options expire on the Saturday
# following the third Friday of the month. The reason that equity and
# index options expire on this day is due to the fact that this day offers
# the least number of scheduling conflicts, i.e. holidays.

# When an options expiration date falls on a holiday, all trading dates
# are moved earlier. For example, in 2008, options expiration date falls
# on Good Friday. In this situation, options will still expire on
# Saturday following Good Friday -- however the last trading day for
# Equity options will be the Thursday preceding the Good Friday trading
# holiday.

yy <- 2011
(d1 <- dateSeq(paste(yy, '-01-01', sep=''), len=12, by='months'))
(d2 <- dateAlign(d1, by='months', dir=-1))
(d3 <- dateAlign(d2, by='weeks', week.align=5))
(d4 <- dateWarp(d3, 14, by='days'))
(d5 <- dateAlign(d4, by='bizdays@NYSEC', dir=-1))

# Find option expiration dates that have been shifted because they would have
# occured on a holiday
yy <- 1990
d1 <- dateSeq(paste(yy, '-01-01', sep=''), len=288, by='months')
d2 <- dateAlign(d1, by='months', dir=-1)
d3 <- dateAlign(d2, by='weeks', week.align=5)
d4 <- dateWarp(d3, 14, by='days')
d5 <- dateAlign(d4, by='bizdays@NYSEC', dir=-1)
data.frame(holiday=d4, option.expiration=d5)[which(d4 != d5), ]
# }