| seq.POSIXt {base} | R Documentation |
The method for seq for date-time classes.
## S3 method for class 'POSIXt' seq(from, to, by, length.out = NULL, along.with = NULL, ...)
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. |
by can be specified in several ways.
A number, taken to be in seconds.
A object of class difftime
A character string, containing one of "sec",
"min", "hour", "day", "DSTday",
"week", "month", "quarter" or "year".
This can optionally be preceded by a (positive or negative) integer
and a space, or followed by "s".
The difference between "day" and "DSTday" is that the
former ignores changes to/from daylight savings time and the latter takes
the same clock time each day. "week" ignores DST (it is a
period of 144 hours), but "7 DSTdays" can be used as an
alternative. "month" and "year" allow for DST.
The time zone of the result is taken from from: remember
that GMT means UTC (and not the time zone of Greenwich, England) and so
does not have daylight savings time.
Using "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.
A vector of class "POSIXct".
## 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)