att.put.nc: Put a NetCDF Attribute

Description Usage Arguments Details Note Author(s) References Examples

View source: R/RNetCDF.R

Description

Put an attribute to a NetCDF dataset.

Usage

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att.put.nc(ncfile, variable, name, type, value)

Arguments

ncfile

Object of class "NetCDF" which points to the NetCDF dataset (as returned from open.nc).

variable

ID or name of the variable to which the attribute will be assigned or "NC_GLOBAL" for a global attribute.

name

Attribute name. Must begin with an alphabetic character, followed by zero or more alphanumeric characters including the underscore ("_"). Case is significant. Attribute name conventions are assumed by some NetCDF generic applications, e.g., units as the name for a string attribute that gives the units for a NetCDF variable.

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.

value

Attribute value. This can be either a single numeric value or a vector of numeric values, or alternatively a character string.

Details

Names commencing with underscore ("_") are reserved for use by the NetCDF library. Most generic applications that process NetCDF datasets assume standard attribute conventions and it is strongly recommended that these be followed unless there are good reasons for not doing so.

Text represented by R type character can be written to NetCDF types NC_CHAR and NC_STRING, and R type raw can be written to NetCDF type NC_CHAR.

R numeric and integer variables can be written to NetCDF numeric types. The NetCDF library handles type conversions, but conversions of values outside the range of a type will result in an error. Due to the lack of native support for 64-bit integers in R, this function accepts integer64 vectors.

Note

NC_BYTE is always interpreted as signed.

Author(s)

Pavel Michna, Milton Woods

References

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

Examples

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##  Create a new NetCDF dataset and define two dimensions
file1 <- tempfile("att.put_", 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))

##  Put some attributes
att.put.nc(nc, "temperature", "_FillValue", "NC_DOUBLE", -99999.9)
att.put.nc(nc, "temperature", "long_name", "NC_CHAR", "air temperature")
att.put.nc(nc, "NC_GLOBAL", "title", "NC_CHAR", "Data from Foo")
att.put.nc(nc, "NC_GLOBAL", "history", "NC_CHAR", paste("Created on", date()))

close.nc(nc)
unlink(file1)

RNetCDF documentation built on Aug. 20, 2021, 9:08 a.m.