R: Inquire About a NetCDF Variable

var.inq.nc {RNetCDF} | R Documentation

## Inquire About a NetCDF Variable

### Description

Inquire about a NetCDF variable.

### Usage

    var.inq.nc(ncfile, variable)

### Arguments

`ncfile` | Object of class "`NetCDF`" which points to the NetCDF dataset (as returned from `open.nc`).
`variable` | Either the ID or the name of the variable to be inquired.

### Details

This function returns information about a NetCDF variable. Information about a variable include its name, its ID, its type, its number of dimensions, a vector of the dimension IDs of this variable and the number of attributes.

### Value

A list of named components, some of which are only included for datasets in "netcdf4" format (as indicated by `file.inq.nc`).

`id` | Variable ID.
`name` | Variable name.
`type` | External NetCDF data type as one of the following labels: `NC_BYTE`, `NC_UBYTE`, `NC_CHAR`, `NC_SHORT`, `NC_USHORT`, `NC_INT`, `NC_UINT`, `NC_INT64`, `NC_UINT64`, `NC_FLOAT`, `NC_DOUBLE`, `NC_STRING`, or a user-defined type name.
`ndims` | Number of dimensions the variable was defined as using.
`dimids` | Vector of dimension IDs corresponding to the variable dimensions (`NA` for scalar variables). Order is leftmost varying fastest.
`natts` | Number of variable attributes assigned to this variable.

The arguments below apply only to datasets in "netcdf4" format:

`chunksizes` | Chunk size expressed as the number of elements along each dimension, in the same order as `dimids`. `NULL` implies contiguous storage.
`cache_bytes` | Size of chunk cache in bytes (`NULL` if unsupported).
`cache_slots` | The number of slots in the chunk cache (`NULL` if unsupported).
`cache_preemption` | A value between 0 and 1 (inclusive) that biases the cache scheme towards eviction of chunks that have been fully read (`NULL` if unsupported).
`deflate` | Integer indicating level of compression, from 0 (minimum) to 9 (maximum), or `NA` if compression is not enabled.
`shuffle` | `TRUE` if byte shuffling is enabled for the variable, `FALSE` otherwise.
`big_endian` | Byte order of the variable. `TRUE` for big-endian, `FALSE` for little-endian, `NA` for not yet determined, or `NULL` if unsupported.
`fletcher32` | `TRUE` if the fletcher32 checksum is enabled for this variable, `FALSE` otherwise.
`szip_options` | Integer containing a bitmask of szip options. `NA` if szip is not used, or `NULL` if unsupported.
`szip_bits` | Number of bits per pixel for szip. `NA` if szip is not used, or `NULL` if unsupported.
`filter_id` | Identifier of filter associated with the variable. `NA` if no filter is defined, or `NULL` if unsupported.
`filter_params` | Vector of integer parameters for the filter associated with the variable. `NA` if no filter is defined, or `NULL` if unsupported.

### Author(s)

Pavel Michna, Milton Woods

### References

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

### Examples

    ##  Create a new NetCDF dataset and define two dimensions
    file1 <- tempfile("var.inq_", fileext=".nc")
    nc <- create.nc(file1)

    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))

    ##  Inquire about these variables
    var.inq.nc(nc, 0)
    var.inq.nc(nc, "temperature")

    close.nc(nc)
    unlink(file1)

[Package RNetCDF version 2.4-2 Index]