This function is, indeed, endpoints in xts that works with Raster*TS objects. It returns a numeric vector corresponding to the last observation in each period specified by on, with a zero added to the beginning of the vector, and the index of the last raster in x at the end.Valid values for the argument on include: us (microseconds),
microseconds, ms (milliseconds),
milliseconds, secs (seconds),
seconds, mins (minutes), minutes,
hours, days, weeks, months, quarters,
and years.