NCObject: NetCDF base object

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

NetCDF base object

Description

This class is a basic ancestor to all classes that represent netCDF objects, specifically groups, dimensions, variables and the user-defined types in a netCDF file. More useful classes use this class as ancestor.

The fields in this class are common among all netCDF objects. In addition, this class manages the attributes for its descendent classes.

Public fields

id

Numeric identifier of the netCDF object.

name

The name of the netCDF object.

attributes

data.frame with the attributes of the netCDF object.

Methods

Public methods

• NCObject$new()

• NCObject$print_attributes()

• NCObject$attribute()

• NCObject$set_attribute()

• NCObject$append_attribute()

• NCObject$delete_attribute()

• NCObject$write_attributes()

• NCObject$clone()

---

Method new()

Create a new netCDF object. This class should not be instantiated directly, create descendant objects instead.

Usage

NCObject$new(id, name)

Arguments

id

Numeric identifier of the netCDF object.

name

Character string with the name of the netCDF object.

---

Method print_attributes()

This function prints the attributes of the netCDF object to the console. Through object linkages, this also applies to the CF data variables and axes, which each link to a netCDF object.

Usage

NCObject$print_attributes(width = 50L)

Arguments

width

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

---

Method attribute()

This method returns an attribute of a netCDF object.

Usage

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

Arguments

att

Attribute name whose value 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.

---

Method set_attribute()

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

Usage

NCObject$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

NCObject$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.

---

Method delete_attribute()

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

Usage

NCObject$delete_attribute(name)

Arguments

name

Vector of names of the attributes to delete.

Returns

Self, invisibly.

---

Method write_attributes()

Write the attributes of this object to a netCDF file.

Usage

NCObject$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.

---

Method clone()

The objects of this class are cloneable with this method.

Usage

NCObject$clone(deep = FALSE)

Arguments

deep

Whether to make a deep clone.

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