CF base object

This class is a basic ancestor to all classes that represent CF objects. More useful classes use this class as ancestor.

Active bindings

friendlyClassName

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

id

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

name

Set or retrieve the name of the CF object. The name must be a valid netCDF name: start with a character, use only characters, numbers and the underscore, and be at most 255 characters long.

fullname

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

group

Set or retrieve the CFGroup that this object is located in, possibly NULL.

attributes

(read-only) Retrieve a data.frame with the attributes of the CF object.

has_resource

(read-only) Flag that indicates if this object has an underlying netCDF resource.

NC

(read-only) The NC object that links to an underlying netCDF resource, or NULL if not linked.

is_dirty

Flag to indicate if the object has any unsaved changes.

Methods

Public methods

• CFObject$new()

• CFObject$attach_to_group()

• CFObject$detach()

• CFObject$attribute()

• CFObject$print_attributes()

• CFObject$set_attribute()

• CFObject$attributes_identical()

• CFObject$append_attribute()

• CFObject$delete_attribute()

• CFObject$write_attributes()

• CFObject$clone()

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Method new()

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

Usage

CFObject$new(obj, attributes = data.frame(), group = NULL)

Arguments

obj

The NCObject instance upon which this CF object is based when read from a netCDF resource, or the name for the new CF object to be created.

attributes

Optional. A data.frame with the attributes of the object. When argument obj is an NCGroup instance and this argument is an empty data.frame (default), arguments will be read from the resource.

group

The CFGroup instance that this object will live in. The default is NULL but this is only useful for CFGroup instance.

Returns

A CFObject instance.

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Method attach_to_group()

Attach this CF object to a group. If there is another object with the same name in this group an error is thrown. This is the basic method that may be overridden by descendant classes.

Usage

CFObject$attach_to_group(grp, locations = list())

Arguments

grp

An instance of CFGroup.

locations

Optional. A list whose named elements correspond to the names of objects, possibly including this object. Each list element has a single character string indicating the group in the hierarchy where the object should be stored. As an example, if a data variable has axes "lon" and "lat" and they should be stored in the parent group of grp, then specify locations = list(lon = "..", lat = ".."). Locations can use absolute paths or relative paths from group grp. If the argument locations is not provided or the name of the object is not in the list, the object will be stored in group grp.

Returns

Self, invisibly.

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Method detach()

Detach the current object from its underlying netCDF resource.

Usage

CFObject$detach()

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Method attribute()

Retrieve an attribute of a CF object.

Usage

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

Arguments

att

Single character string of attribute 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 = 30L)

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.

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Method attributes_identical()

Test if the supplied attributes are identical to the attributes of this instance. The order of the attributes may differ but the names, types and values must coincide.

Usage

CFObject$attributes_identical(cmp)

Arguments

cmp

data.frame with attributes to compare to the attributes of this instance.

Returns

TRUE if attributes in argument cmp are identical to the attributes of this instance, FALSE otherwise.

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

Usage

CFObject$delete_attribute(name)

Arguments

name

Vector of names of the attributes 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()

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.