NetCDF group

This class represents a netCDF group, the object that holds elements like dimensions and variables of a netCDF file.

Direct access to groups is usually not necessary. The principal objects of interest, CF data variables and axes, are accessible via CFGroup. Changing the properties of a netCDF group other than its name may very well invalidate the CF objects or even the netCDF file.

Super class

ncdfCF::NCObject -> NCGroup

Public fields

parent

Parent group of this group, the owning CFDataset for the root group.

subgroups

List of child NCGroup instances of this group.

NCvars

List of netCDF variables that are located in this group.

NCdims

List of netCDF dimensions that are located in this group.

NCudts

List of netCDF user-defined types that are located in this group.

Active bindings

friendlyClassName

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

resource

(read-only) The RNetCDF object to the underlying netCDF resource.

handle

(read-only) Get the handle to the netCDF resource for the group

can_write

(read-only) Is the resource writable?

name

Set or retrieve the name of the group. Note that the name is always relative to the location in the hierarchy that the group is in and it should thus not be qualified by backslashes. The name has to be a valid CF name. The name of the root group cannot be changed.

fullname

(read-only) The fully qualified absolute path of the group.

root

(read-only) Retrieve the root group.

CF

Set or retrieve the CFGroup that is associated with this NC group.

Methods

Public methods

• NCGroup$new()

• NCGroup$print()

• NCGroup$find_by_name()

• NCGroup$find_dim_by_id()

• NCGroup$has_name()

• NCGroup$set_name()

• NCGroup$unused()

• NCGroup$create_group()

• NCGroup$append()

• NCGroup$fullnames()

• NCGroup$dimensions()

• NCGroup$clone()

Inherited methods

• ncdfCF::NCObject$attribute()
• ncdfCF::NCObject$print_attributes()
• ncdfCF::NCObject$write_attributes()

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Method new()

Create a new instance of this class.

Usage

NCGroup$new(id, name, attributes = data.frame(), parent, resource)

Arguments

id

The identifier of the group. If NA, the new group will be created in the netCDF resource, unless argument parent == NULL, i.e. the root group which already exists.

name

The name of the group.

attributes

Optional, a data.frame with group attributes.

parent

The parent group of this group. If NULL then argument resource must be a valid instance of NCResource.

resource

Optional. Reference to the NCResource instance that provides access to the netCDF resource.

Returns

An instance of this class.

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Method print()

Summary of the group printed to the console.

Usage

NCGroup$print(stand_alone = TRUE, ...)

Arguments

stand_alone

Logical to indicate if the group should be printed as an object separate from other objects (TRUE, default), or print as part of an enclosing object (FALSE).

...

Passed on to other methods.

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Method find_by_name()

Find an object by its name. Given the name of an object, possibly preceded by an absolute or relative group path, return the object to the caller. Usually this method is called programmatically.

Usage

NCGroup$find_by_name(name)

Arguments

name

The name of an object, with an optional absolute or relative group path from the calling group. The object must be an NC group, dimension or variable.

Returns

The object with the provided name. If the object is not found, returns NULL.

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Method find_dim_by_id()

Find an NC dimension object by its id. Given the id of a dimension, return the NCDimension object to the caller. The dimension has to be found in the current group or any of its parents.

Usage

NCGroup$find_dim_by_id(id)

Arguments

id

The id of the dimension.

Returns

The NCDimension object with an identifier equal to the id argument. If the object is not found, returns NULL.

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Method has_name()

Has a given name been defined in this group already?

Usage

NCGroup$has_name(name)

Arguments

name

Character string. The name will be searched for, regardless of case.

Returns

TRUE if name is present in the group, FALSE otherwise.

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Method set_name()

Change the name of the NC group. The new name must be valid and should not duplicate a sibling group.

Usage

NCGroup$set_name(new_name)

Arguments

new_name

The new name for the NC group.

Returns

Self, invisibly.

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Method unused()

Find NC variables that are not referenced by CF objects. For debugging purposes only.

Usage

NCGroup$unused()

Returns

List of NCVariable.

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Method create_group()

Create a new group as a sub-group of the current group. This writes the new group to the netCDF resource, but only if it is open for writing.

Usage

NCGroup$create_group(CFgroup)

Arguments

CFgroup

The CFGroup associated with this NC group.

Returns

The newly created group as a NCGroup instance, invisibly.

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Method append()

Append an object to this group.

Usage

NCGroup$append(obj)

Arguments

obj

The object to append. This must be an NCVariable or NCDimension instance. Any other type of object will generate a warning.

Returns

Self, invisible.

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Method fullnames()

This method lists the fully qualified name of this group, optionally including names in subgroups.

Usage

NCGroup$fullnames(recursive = TRUE)

Arguments

recursive

Should subgroups be scanned for names too (default is TRUE)?

Returns

A character vector with group names.

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Method dimensions()

List all the dimensions that are visible from this group, possibly including those that are defined in parent groups (by names not defined by any of their child groups in direct lineage to the current group).

Usage

NCGroup$dimensions(scope = "all")

Arguments

scope

Character string that indicates if only dimensions in the current group should be reported (local) or visible dimensions in parent groups as well (all, default).

Returns

A vector of NCDimension objects.

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Method clone()

The objects of this class are cloneable with this method.

Usage

NCGroup$clone(deep = FALSE)

Arguments

deep

Whether to make a deep clone.