var.def.nc: Define a NetCDF Variable

In RNetCDF: Interface to NetCDF Datasets

Description

Define a new NetCDF variable.

Usage

var.def.nc(ncfile, varname, vartype, dimensions)

Arguments

ncfile	Object of class "NetCDF" which points to the NetCDF dataset (as returned from open.nc).
varname	Variable name. Must begin with an alphabetic character, followed by zero or more alphanumeric characters including the underscore ("_"). Case is significant.
vartype	One of the set of predefined NetCDF external data types. The valid NetCDF external data types are NC_BYTE, NC_CHAR, NC_SHORT, NC_INT, NC_FLOAT, and NC_DOUBLE.
dimensions	Vector of ndims dimension IDs or their names corresponding to the variable dimensions or NA if a scalar variable should be created. If the ID (or name) of the unlimited dimension is included, it must be last.

Details

This function creates a new NetCDF variable. A NetCDF variable has a name, a type, and a shape, which are specified when it is defined. A variable may also have values, which are established later in data mode.

Ordinarily, the name, type, and shape are fixed when the variable is first defined. The name may be changed, but the type and shape of a variable cannot be changed. However, a variable defined in terms of the unlimited dimension can grow without bound in that dimension. The fastetst varying dimension has to be first in dimensions, the slowest varying dimension last (this is the same way as an array is defined in R; i.e., opposite to the CDL conventions).

A NetCDF variable in an open NetCDF dataset is referred to by a small integer called a variable ID. Variable IDs are 0, 1, 2,..., in the order in which the variables were defined within a NetCDF dataset.

Attributes may be associated with a variable to specify such properties as units.

Author(s)

Pavel Michna

References

http://www.unidata.ucar.edu/software/netcdf/

Examples

##  Create a new NetCDF dataset and define two dimensions
nc <- create.nc("var.def.nc")

dim.def.nc(nc, "station", 5)
dim.def.nc(nc, "time", unlim=TRUE)

##  Create two variables, one as coordinate variable
var.def.nc(nc, "time", "NC_INT", "time")
var.def.nc(nc, "temperature", "NC_DOUBLE", c(0,1))

close.nc(nc)

RNetCDF documentation built on May 2, 2019, 6:12 p.m.