seq.Date                package:base                R Documentation

Generate Regular Sequences of Dates

Description:

     The method for 'seq' for objects of class class '"Date"'
     representing calendar dates.

Usage:

     ## S3 method for class 'Date':
     seq(from, to, by, length.out = NULL, along.with = NULL, ...)

Arguments:

    from: starting date. Required

      to: end date. Optional.

      by: increment of the sequence. Optional.  See 'Details'.

length.out: integer, optional. desired length of the sequence.

along.with: take the length from the length of this argument.

     ...: arguments passed to or from other methods.

Details:

     'by' can be specified in several ways.

        *  A number, taken to be in days.

        *  A object of class 'difftime'

        *  A character string, containing one of '"day"', '"week"',
           '"month"' or '"year"'.  This can optionally be preceded by a
           (positive or negative) integer and a space, or followed by
           '"s"'.

           See 'seq.POSIXt' for the details of '"month"'.

Value:

     A vector of class '"Date"'.

See Also:

     'Date'

Examples:

     ## first days of years
     seq(as.Date("1910/1/1"), as.Date("1999/1/1"), "years")
     ## by month
     seq(as.Date("2000/1/1"), by="month", length.out=12)
     ## quarters
     seq(as.Date("2000/1/1"), as.Date("2003/1/1"), by="3 months")

     ## find all 7th of the month between two dates, the last being a 7th.
     st <- as.Date("1998-12-17")
     en <- as.Date("2000-1-7")
     ll <- seq(en, st, by="-1 month")
     rev(ll[ll > st & ll < en])

