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 is ignored, and a warning message is generated when
the sequence is used. If length is present and not being ignored, it must
be non-negative (that is, a zero-length sequence is equivalent to timeDate()).
Otherwise, to have a valid sequence, adding by to from must go
towards to. 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 fails if the input is not a regular
sequence within a tolerance given by timeDateOptions("ts.eps").
Most operations that work for timeDate objects also work on timeSequence
objects (for example, mathematical functions, arithmetic,
comparison operators, and subscripting) by first coercing to a time/date
vector. Therefore they 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.
timeSequence function.