ULTIMATE SOLUTION TO FINALLY TEACH DATA TREES

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Permalink Reply by David Rutten on September 1, 2016 at 5:49am

I don't recommend using the FAQ post about this as instruction material, but I do think the example it uses (breps, faces, contours, points) is an understandable one that shows the sort of complexity you have to deal with when designing algorithms.

A completely different approach would be to not try and justify the existence of data-trees at all, but merely state that data is organised in lists (where all the data inside a single list is considered to belong together) and then you can have any number of lists, each of which is identified not by a textual name or a single number, but by a string of integers {0}, {0;5}, {5:0;0;0;3;12}. These integers can/should be used to describe how various lists relate to each other. The more integers two lists have in common, the more related they are.

I do prefer to explain why things exist and are the way they are, datatrees are frustratingly complicated enough without having to deal with them in lieu of any fundamental understanding.

Permalink Reply by Armin Seltz on September 1, 2016 at 6:26am

I found it just takes some time and doing a lot of examples, trial and error and so on, before I "got" how data structures work and a little bit longer to actually manage them as needed. In the beginning its good to a) use simplify whereever possible to keep things tidy and b) use panels everywhere to see whats happening.

I quite liked the Intro to Grasshopper series by Daniel Christev (https://www.youtube.com/playlist?list=PLXekJiZsSipBXda0RJF-wJVHNPKT...) and the essentials series by the friendly folks at ReseArch (http://www.rese-arch.org/bundle/essentials), which go really in-depth (3hrs just on data trees!). 

In the end I believe there is no quick explanation of data trees or at least not in a one-stop-solution way to work with them in all situations. Sometimes things just get really complicated and our brain cant think in so many dimensions, so it needs some time of working with it.

Best of Luck with the course, Franceso, hopefully I can join next year ;)

Permalink Reply by Alessio Erioli on September 22, 2016 at 6:43pm

The efficacy of the explanation depends on the student's background, their capacity of abstraction and the metaphors they are able to grasp.

In the case of people with little to none previous experience in programming I found that the best way to explain data structure is a real-life case scenario (even pretty mundane) where you actually need a tree to organize things (no matter what those things are, it is their organization that matters in this case), and then show how and why it is important in the articulation of data inside Grasshopper.

Typically I make the case of a restaurant. It's quite verbose (sorry for the long post that follows), but hopefully didactic enough.

Let's say that you open a new restaurant and want to start small, so you can serve one client at the time: keeping track of his/her order is easy, it's just one (case of single data). The client is satisfied, the buzz spreads so you are able to afford to serve a single table with n clients. To keep track of the clients orders you now need a list (case of single list - of which the single data is a particular case). Things are going well. So now you can afford other two tables. How do you keep track of the orders? You number the tables {0}, {1} and {2}, each table with its separately processed list of orders. So now you know that if you need to look for the order of a particular client you first need to look for the right table number and then the client number at that table.
Either you're in luck or you're really good: now you can expand your restaurant in a second room, with 4 more tables. So now, you'll have the tables in room {0} and the ones in room {1}. Respectively: {0;0}, {0;1}, {0;2} and {1;0},{1;1}, {1;2}, {1;3}. Welcome to data trees (of which a list is a particular case of a tree with a single branch, of which....).

Ok, I think you get the idea..... next step would be opening on another building, with 3 rooms, each of which has..... (and so on and so forth). Turns out you are a famous franchise or something like that.

The important things about this example (besides talking about food - so you immediately get everyone's attention) in my opinion are:

. it grows from simple to complex, allowing the metaphor to grow along in the learner's mind before goin into a visual reference

. it teases the necessity of a tree structure to organize data, rather than imposing it without any basis

. it has a grasp to a real-life case, so people can relate to it

The complex operations require practice in order to become fluent with data trees, and that depends only on how much practice one needs to acquire the required fluency, but I believe this simple example can give a good foundation on the basic concepts.

Hope this was helpful!

Permalink Reply by Armin Seltz on September 23, 2016 at 2:32am

Nice, I really like the restaurant analogy! It can be taken much further with mathematical operations for each table (like splitting the bill between all people at a table) or simply calculating the sum of all orders (using mass addition). Then you could move to actually visually building something that is still related, like building a graph in 3D that maps spending or even transforming some chairs around a table depending on how many people at each table (coming from random range).

Must remember this if I finally get to teach some Grasshopper!

Permalink Reply by David Rutten on September 23, 2016 at 3:21am

I like it! Now I'm hungry...

Permalink Reply by ng5 Alex on September 23, 2016 at 4:06am

Hello,

Great analogy and example.

For the introduction to data trees i was using the phone agenda example, where A phone numbers are {0}, B {1} and so on. To continue to branch paths depth, each letter, would be partitioned to close friends, relatives, work etc, having 0;0, 0;1..., 1;0.,1;1..

Next would be a city, with blocks, roads, addresses, buildings, flats, occupants and encouraged students to suggest trees.

Along with some diagrammatic sketches I am sticking with the restaurant from now on. It seems logical, to have to organize data through this analogy.

Thank you for sharing this.

best

alex

ps. It seems also that physical phone agendas are not popular nowadays, thanks to mobiles.

Permalink Reply by David Stasiuk on September 23, 2016 at 6:38am

Sending this to my students now!

Permalink Reply by Kim hauer on September 23, 2016 at 2:55pm

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