Zarr Hierarchy node

This class implements a Zarr node. The node is an element in the hierarchy of the Zarr object. As per the Zarr specification, the node is either a group or an array. Thus, this class is the ancestor of the zarr_group and zarr_array classes. This class manages common features such as names, key, prefixes and paths, as well as the hierarchy between nodes and the zarr_store for persistent storage.

This class should never have to be instantiated or accessed directly. Instead, use instances of zarr_group or zarr_array. Function arguments are largely not checked, the group and array instances should do so prior to calling methods here. The big exception is checking the validity of node names.

Active bindings

name

(read-only) The name of the node.

parent

(read-only) The parent of the node. For a root node this returns NULL, otherwise this zarr_group or zarr_array instance.

store

(read-only) The store of the node.

path

(read-only) The path of this node, relative to the root node of the hierarchy.

prefix

(read-only) The prefix of this node, relative to the root node of the hierarchy.

metadata

(read-only) The metadata document of this node, a list.

attributes

(read-only) Retrieve the list of attributes of this object. Attributes can be added or modified with the set_attribute() method or removed with the delete_attributes() method.

Methods

Public methods

• zarr_node$new()

• zarr_node$print_attributes()

• zarr_node$set_attribute()

• zarr_node$delete_attributes()

• zarr_node$save()

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Method new()

Initialize a new node in a Zarr hierarchy.

Usage

zarr_node$new(name, metadata, parent, store)

Arguments

name

The name of the node.

metadata

List with the metadata of the node.

parent

The parent node of this new node. Must be omitted when initializing a root node.

store

The store to persist data in. Ignored if a parent is specified.

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Method print_attributes()

Print the metadata "attributes" to the console. Usually called by the zarr_group and zarr_array print() methods.

Usage

zarr_node$print_attributes(...)

Arguments

...

Arguments passed to embedded functions. Of particular interest is width = . to specify the maximum width of the columns.

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Method set_attribute()

Add an attribute to the metadata of the object. If an attribute name already exists, it will be overwritten.

Usage

zarr_node$set_attribute(name, 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.

value

The value of the attribute. This can be of any supported type, including a vector or list of values. 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.

Returns

Self, invisibly.

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Method delete_attributes()

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

Usage

zarr_node$delete_attributes(name)

Arguments

name

Vector of names of the attributes to delete.

Returns

Self, invisibly.

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Method save()

Persist any edits to the group or array to the store.

Usage

zarr_node$save()