resampleUVdata: Resample Unit-Value Data
In USGS-R/rloadest: River Load Estimation

Unit-value data can be recorded at any arbitrary intervals. For some applications, such as load estimates, a uniform series is required. The resampleUVdata function resamples the orginal unit-value data to a consistent time interval.

1 2	resampleUVdata(UVdata, time.step = 15, start.date = "", end.date = "", max.diff = "2 hours", missing.days = "exclude")

`UVdata`	the dataset containing the unit-values data. Must have one column that represents the time of the observation that is class "POSIXt." Missing values are not permitted in that column.
`time.step`	the time step of the new data in minutes; must divide an hour exactly evenly. The default value is 15 minutes.
`start.date`	a character string indicating the first day of the output dataset. The default value ("") indicates use the first day in `UVdata`.
`end.date`	a character string indicating the last day of the output dataset. The default value ("") indicates use the last day in `UVdata`.
`max.diff`	a character string indicating the maximum difference in time to sucessfully resample the unit-value data. The default is "2 hours" see `mergeNearest` for details.
`missing.days`	a characer string indicating what action should be taken for days not present in `UVdata`. Must be either "exclude" to remove those days from the output, or "include" to retain them. Can be abbreviated. If `missing.days` is "include," then partial days within `max.diff` will be included in the output data frame.