| % File src/library/base/man/seq.POSIXt.Rd |
| % Part of the R package, https://www.R-project.org |
| % Copyright 1995-2017 R Core Team |
| % Distributed under GPL 2 or later |
| |
| \name{seq.POSIXt} |
| \alias{seq.POSIXt} |
| \title{Generate Regular Sequences of Times} |
| \description{ |
| The method for \code{\link{seq}} for date-time classes. |
| } |
| \usage{ |
| \method{seq}{POSIXt}(from, to, by, length.out = NULL, along.with = NULL, \dots) |
| } |
| \arguments{ |
| \item{from}{starting date. Required.} |
| \item{to}{end date. Optional.} |
| \item{by}{increment of the sequence. Optional. See \sQuote{Details}.} |
| \item{length.out}{integer, optional. Desired length of the sequence.} |
| \item{along.with}{take the length from the length of this argument.} |
| \item{\dots}{arguments passed to or from other methods.} |
| } |
| \details{ |
| \code{by} can be specified in several ways. |
| \itemize{ |
| \item A number, taken to be in seconds. |
| \item A object of class \code{\link{difftime}} |
| \item A character string, containing one of \code{"sec"}, |
| \code{"min"}, \code{"hour"}, \code{"day"}, \code{"DSTday"}, |
| \code{"week"}, \code{"month"}, \code{"quarter"} or \code{"year"}. |
| This can optionally be preceded by a (positive or negative) integer |
| and a space, or followed by \code{"s"}. |
| } |
| The difference between \code{"day"} and \code{"DSTday"} is that the |
| former ignores changes to/from daylight savings time and the latter takes |
| the same clock time each day. \code{"week"} ignores DST (it is a |
| period of 144 hours), but \code{"7 DSTdays"} can be used as an |
| alternative. \code{"month"} and \code{"year"} allow for DST. |
| |
| The \link{time zone} of the result is taken from \code{from}: remember |
| that GMT means UTC (and not the time zone of Greenwich, England) and so |
| does not have daylight savings time. |
| |
| Using \code{"month"} first advances the month without changing the |
| day: if this results in an invalid day of the month, it is counted |
| forward into the next month: see the examples. |
| } |
| \value{ |
| A vector of class \code{"POSIXct"}. |
| } |
| |
| \seealso{\code{\link{DateTimeClasses}}} |
| |
| \examples{ |
| ## first days of years |
| seq(ISOdate(1910,1,1), ISOdate(1999,1,1), "years") |
| ## by month |
| seq(ISOdate(2000,1,1), by = "month", length.out = 12) |
| seq(ISOdate(2000,1,31), by = "month", length.out = 4) |
| ## quarters |
| seq(ISOdate(1990,1,1), ISOdate(2000,1,1), by = "quarter") # or "3 months" |
| ## days vs DSTdays: use c() to lose the time zone. |
| seq(c(ISOdate(2000,3,20)), by = "day", length.out = 10) |
| seq(c(ISOdate(2000,3,20)), by = "DSTday", length.out = 10) |
| seq(c(ISOdate(2000,3,20)), by = "7 DSTdays", length.out = 4) |
| } |
| \keyword{manip} |
| \keyword{chron} |