timeSequence class is a compact representation of a
time/date vector in an arithemetic sequence.
timeDate) the start of the sequence.
timeDate) the end of the sequence.
timeInterval) the increment for the sequence.
integer) the length of the sequence.
event) time periods to remove from the sequence.
positionsCalendar) times/dates to add to the sequence.
character) the time/date output format for sequence display.
character) the time zone for the sequence.
The
timeSequence class extends the
positionsCalendar class.
Valid
timeSequence objects must contain a single non-
NA value in
at least three of the
from,
to,
by, and
length slots.
If all four are present, the
length
slot will be ignored, and a warning message will be generated when
the sequence is used. If
length is present and not being ignored, it must
be non-negative [a zero-length sequence is equivalent to
timeDate()].
Otherwise, adding
by to
from must go towards
to
in order to have a valid sequence. The
default sequence [generated by calling
timeSequence() or
new("timeSequence")
] has length 0.
A
timeSequence can be coerced to
timeDate using
as,
and regularly spaced times/dates (or time/date vectors spaced
by regular numbers of months) can be coerced to
timeSequence
using
as, [this will fail if the input is not a regular
sequence within a tolerance given by
options("ts.eps")]. Most
operations that work for
timeDate objects also work on
timeSequence
objects (e.g. mathematical functions, arithmetic,
comparison operators, subscripting), by first coercing to a time/date
vector; they therefore do not return
timeSequence objects. Because
of this, it is more efficient to coerce a
timeSequence
to
timeDate using
as before performing an extended set of
calculations on the original object, rather than coercing
for each operation.