CFtime (version 1.6.1)

+.CFTime: Extend a CFTime object

Description

A CFTime instance can be extended with this operator, using values from another CFTime instance, or a vector of numeric offsets or character timestamps. If the values come from another CFTime instance, the calendars of the two instances must be compatible If the calendars of the CFTime instances are not compatible, an error is thrown.

Usage

# S3 method for CFTime
+(e1, e2)

Value

A CFTime object with the offsets of argument e1 extended by the values from argument e2.

Arguments

e1

Instance of the CFTime class.

e2

Instance of the CFTime class with a calendar compatible with that of argument e1, or a numeric vector with offsets from the origin of argument e1, or a vector of character timestamps in ISO8601 or UDUNITS format.

Details

The resulting CFTime instance will have the offsets of the original CFTime instance, appended with offsets from argument e2 in the order that they are specified. If the new sequence of offsets is not monotonically increasing a warning is generated (the COARDS metadata convention requires offsets to be monotonically increasing).

There is no reordering or removal of duplicates. This is because the time series are usually associated with a data set and the correspondence between the data in the files and the CFTime instance is thus preserved. When merging the data sets described by this time series, the order must be identical to the merging here.

Note that when adding multiple vectors of offsets to a CFTime instance, it is more efficient to first concatenate the vectors and then do a final addition to the CFTime instance. So avoid CFtime(definition, calendar, e1) + CFtime(definition, calendar, e2) + CFtime(definition, calendar, e3) + ... but rather do CFtime(definition, calendar) + c(e1, e2, e3, ...). It is the responsibility of the operator to ensure that the offsets of the different data sets are in reference to the same calendar.

Note also that RNetCDF and ncdf4 packages both return the values of the "time" dimension as a 1-dimensional array. You have to dim(time_values) <- NULL to de-class the array to a vector before adding offsets to an existing CFtime instance.

Any bounds that were set will be removed. Use bounds() to retrieve the bounds of the individual CFTime instances and then set them again after merging the two instances.

Examples

e1 <- CFtime("days since 1850-01-01", "gregorian", 0:364)
e2 <- CFtime("days since 1850-01-01 00:00:00", "standard", 365:729)
e1 + e2