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 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.