what's it called when you have a data structure that looks like an org chart?

Question

This is me showing that I didn't get a CS degree. What I'm wondering is what the heck you call this:

• every node has a id (unique) and a parentId
• the node at the top of the tree has no parentId
• a parent node can have 0...n child nodes, or maybe it's more correct to say that a parent node id can appear in 0..n nodes

Seems simple right? But it's not a b-tree as far as I can tell, since it's not balanced. Is it an unbalanced tree? Couldn't find an entry in wikipedia for that so I assume that the term doesn't exist.

Edit: I was really stuck on this thing not being a b-tree, so I thought there would be a term for trees that are not balanced. And there is: tree.

Answer 1

Isn't it a simple tree?

Answer 2

I would simply call it a tree. Though technically there may be a term for a non-binary && non-balanced tree. IMO, tree works fine. I might also refer to it as hierarchical data.

Answer 3

It's just a tree. There's no need for any more distinction than that, IMO.

Answer 4

A really screwed up organization may only be able to represented by a graph. ;-)

Answer 5

At the most general it is a graph. Since there is a directed relationship between the nodes (namely from the child nodes to the parent) it is also a directed graph or digraph. Presumably there are no loops in the graph (i.e. A -> B, B -> C, C -> A) so it is an directed acyclical graph (DAG). And since there is also likely to be a single root node it is also a tree.

Answer 6

As long as any one node does not reference more than one direct parent, then it can be a tree.

Answer 7

As everyone points out, you probably don't need anything more complicated than a tree.

To the more complicated structures like a graph, it's not entirely crazy.

See Martin Fowler's paper on accountability structures. That said, I can say from first hand experience, it's better to avoid modeling an org tree as a graph, when you don't need it.

Answer 8

A mathematician would say it is a rooted tree, as in graph theory trees need not have a root.

In computer science almost all trees come with roots, so as the others have pointed out it is called just a tree.