var.get.ncv {ncvar}R Documentation

Get a NetCDF Variable

Description

Get data and associated metadata of a NetCDF variable.

Usage

var.get.ncv(path, name, start=NA, count=NA, mode="attonly", 
    data=TRUE, gatts=FALSE, coord=FALSE, recursion=0, verbose=FALSE)

Arguments

path Filename of the NetCDF file to be opened.
name Name of the variable.
start A vector of indices indicating where to start reading the values (beginning at 1). The length of this vector must equal the number of dimensions the variable. If not specified (start=NA), the entire variable is read.
count A vector of integers indicating the number of values to read along each dimension. The length of this vector must equal the number of dimensions the variable. If not specified (count=NA), the entire variable is read.
mode the read mode, determines which metadata is read. Currently the following modes are supported: "nometa", no additional metadata is returned; "attonly", the variables attributes are returned; "netcdf", the coordinate variables as defined by the NetCDF user guide and associated attributes are returned; "cf", all coordinate related variables and associated attributes are returned (coordinate and auxillary coordinate variables, grid mapping variables); "cf-full", all metadata associated with the variable as defined in the CF-conventions is returned.
data Set to FALSE, if only metadata should be read.
gatts Set to TRUE, if global attributes should be read.
coord For internal use only.
recursion For internal use only.
verbose For internal use only.

Details

This function returns the data and associated metadata of a variable. If the read procedure fails (e.g., no variable with the corresponding name), NULL is returned. Returned data are either of type R integer or R double precision.

Values of NA are supported; values in the data file that match the variable's missing value attribute (_FillValule) are automatically converted to NA before being returned to the user.

Data in a NetCDF file is conceived as being a multi-dimensional array. The number and length of dimensions is determined when the variable is created. The start and count indices that this routine takes indicate where the reading starts along each dimension, and the count of values along each dimension to read.

Note that the order of dimensions is consistent with the R conventions (the first dimension varies fastest), but opposite to the CDL conventions.

Value

An object of class "var.ncv", including the variables data and metadata.

Author(s)

Juerg Schmidli

References

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

Examples

## Reads a variable and associated metadata from the file created with
## foo.ncv()

foo.ncv()
pre <- var.get.ncv(paste(tempdir(),"/foo.nc",sep=""), "temperature")


[Package ncvar version 1.0-3 Index]