As of Grasshopper 0.6, data can be stored in hierarchical structures not dissimilar to a branching tree.

Data is still stored in lists; however, each list now has a series of indices describing the unique position of the data within a larger data framework. This framework is not unlike a Data Dictionary in that it contains a list of all transactions in the Grasshopper Definition and the number of associated entities per transaction. In Grasshopper this framework is referred to as a Data Tree. It is important to remember that the Data Tree does not contain any of the actual data in the Grasshopper Definition, only bookkeeping information for managing it.

Data Trees can be visualized in Grasshopper using the Parameter Viewer in which you can toggle between the visualization of the Data Tree as a branching diagram or a per-Path address.

This Primer incrementally constructs a Data Tree- from trunk to leaves.

Download the Grasshopper Definition (version 0.6.0019) from modeLab.