This function converts from real times/dates to numeric times (0, 1, 2, ...)
time_to_numeric(x, origin, unit)
a list of data frames that can be passed to libbi
a data frame containing a "time" column, or a list containing such data frames
the time origin, i.e. the date or time corresponding to time 0
the unit of time that each time step corresponds to; this must be
a unit understood by lubridate::period
, optionally with a number in
advance, e.g. "day" or "2 weeks" or "3 seconds"