This page extends xarray’s page on terminology.

Terminology

DataTree

A tree-like collection of Dataset objects. A tree is made up of one or more nodes, each of which can store the same information as a single Dataset (accessed via .ds). This data is stored in the same way as in a Dataset, i.e. in the form of data variables (see Variable in the corresponding xarray terminology page), dimensions, coordinates, and attributes.

The nodes in a tree are linked to one another, and each node is it’s own instance of DataTree object. Each node can have zero or more children (stored in a dictionary-like manner under their corresponding names), and those child nodes can themselves have children. If a node is a child of another node that other node is said to be its parent. Nodes can have a maximum of one parent, and if a node has no parent it is said to be the root node of that tree.

Subtree

A section of a tree, consisting of a node along with all the child nodes below it (and the child nodes below them, i.e. all so-called descendant nodes). Excludes the parent node and all nodes above.

Group

Another word for a subtree, reflecting how the hierarchical structure of a DataTree allows for grouping related data together. Analogous to a single netCDF group or Zarr group.