get parent ids and link data from a node datum
the node data to get parent ids from
the order that the datum was encountered in
parentData - the parent ids and link data that correspond to the node datum, undefined is the same as empty
Generated using TypeDoc
The interface for getting the parent ids and link data from the current node data. This must return an array of parent ids coupled with data (i.e. an array of two element arrays of the form ["Parent Id", data]) for the link between this node and the parent id.
This can be modified with the Stratify#parentData method.