CFObject: CF base object

In ncdfCF: Easy Access to NetCDF Files with CF Metadata Conventions

CF base object

Description

This class is a basic ancestor to all classes that represent CF objects, specifically data variables and axes. More useful classes use this class as ancestor.

Public fields

NCvar

The NCVariable instance that this CF object represents.

group

The NCGroup that this object is located in.

Active bindings

friendlyClassName

(read-only) A nice description of the class.

id

(read-only) The identifier of the CF object.

name

(read-only) The name of the CF object.

fullname

(read-only) The fully-qualified name of the CF object.

attributes

Set or retrieve a data.frame with the attributes of the CF object.

Methods

Public methods

• CFObject$new()

• CFObject$attribute()

• CFObject$print_attributes()

• CFObject$set_attribute()

• CFObject$append_attribute()

• CFObject$delete_attribute()

• CFObject$write_attributes()

• CFObject$clone()

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Method new()

Create a new CF object instance from a variable in a netCDF resource. This method is called upon opening a netCDF resource. It is rarely, if ever, useful to call this constructor directly from the console. Instead, use the methods from higher-level classes such as CFVariable.

Usage

CFObject$new(nc_var, group)

Arguments

nc_var

The NCVariable instance upon which this CF object is based.

group

The NCGroup that this object is located in.

Returns

A CFobject instance.

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Method attribute()

Retrieve attributes of any CF object.

Usage

CFObject$attribute(att, field = "value")

Arguments

att

Vector of character strings of attributes to return.

field

The field of the attribute to return values from. This must be "value" (default) or "type".

Returns

If the field argument is "type", a character string. If field is "value", a single value of the type of the attribute, or a vector when the attribute has multiple values. If no attribute is named with a value of argument att NA is returned.

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Method print_attributes()

Print the attributes of the CF object to the console.

Usage

CFObject$print_attributes(width = 50L)

Arguments

width

The maximum width of each column in the data.frame when printed to the console.

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Method set_attribute()

Add an attribute. If an attribute name already exists, it will be overwritten.

Usage

CFObject$set_attribute(name, type, value)

Arguments

name

The name of the attribute. The name must begin with a letter and be composed of letters, digits, and underscores, with a maximum length of 255 characters. UTF-8 characters are not supported in attribute names.

type

The type of the attribute, as a string value of a netCDF data type.

value

The value of the attribute. This can be of any supported type, including a vector or list of values. Matrices, arrays and like compound data structures should be stored as a data variable, not as an attribute and they are thus not allowed. In general, an attribute should be a character value, a numeric value, a logical value, or a short vector or list of any of these. Values passed in a list will be coerced to their common mode.

Returns

Self, invisibly.

---

Method append_attribute()

Append the text value of an attribute. If an attribute name already exists, the value will be appended to the existing value of the attribute. If the attribute name does not exist it will be created. The attribute must be of "NC_CHAR" or "NC_STRING" type; in the latter case having only a single string value.

Usage

CFObject$append_attribute(name, value, sep = "; ", prepend = FALSE)

Arguments

name

The name of the attribute. The name must begin with a letter and be composed of letters, digits, and underscores, with a maximum length of 255 characters. UTF-8 characters are not supported in attribute names.

value

The character value of the attribute to append. This must be a character string.

sep

The separator to use. Default is "; ".

prepend

Logical to flag if the supplied value should be placed before the existing value. Default is FALSE.

Returns

Self, invisibly.

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Method delete_attribute()

Delete an attribute. If an attribute name is not present this method simply returns.

Usage

CFObject$delete_attribute(name)

Arguments

name

The name of the attribute to delete.

Returns

Self, invisibly.

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Method write_attributes()

Write the attributes of this object to a netCDF file.

Usage

CFObject$write_attributes(nc, nm)

Arguments

nc

The handle to the netCDF file opened for writing.

nm

The NC variable name or "NC_GLOBAL" to write the attributes to.

Returns

Self, invisibly.

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Method clone()

The objects of this class are cloneable with this method.

Usage

CFObject$clone(deep = FALSE)

Arguments

deep

Whether to make a deep clone.

ncdfCF documentation built on April 16, 2025, 9:08 a.m.