| 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" 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 timezone of the result is taken from from: remember
that GMT means UTC (and not the timezone 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 = "3 months") ## days vs DSTdays: use c() to lose the timezone. 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)