Trees

Well, now I realize that the photo of the tree from my previous post would have been better suited here. Oh well!

Conceptually, trees are not an incredibly difficult structure to grasp. From a young age most people have encountered a tree structure of some sort during their daily lives. Probably the most common and boring example is arithmetic expressions from math. Even if these are not thought of by the individual as a tree, they are in fact a type of tree.

Trees obviously come in many different forms, although I'm mainly interested in the computer science variety! Trees in computer science are used to represent structured collections of data. They can be thought of as an upside-down version of a real tree - with the roots at the top. Except, instead of having a vast system of roots, a computer science tree has only one root. From this root there can be any number of branches, each leading to another smaller tree.

The reason trees are so useful is their ability to link data together in a meaningful way. Consider a collection of names. Sure you can store all those names in a python dictionary or list, but if you store them using a tree structure, simply the way that they are organized will impart an extra form of implicit information.

Lets say you wanted to store all the names belonging to a particular family. You could contain them within a list, even have them in some kind of order, but you would essentially just have a list of names. On the other hand, if you store those names using a tree you could have say the great grandfather at the top; his children below that, and their children below that. Hopefully that makes some sort of intuitive sense, considering that this is type of tree is well known and refered to as a 'family tree'.

Of course this description and examples are only the most basic and simplified versions of trees, but hopefully they illustrate a clear image of what a Tree is.