So you want to look at a graph by email: Carlos Scheidegger.
From the post:
Say you are given a graph and are told: “Tell me everything that is interesting about this graph”. What do you do? We visualization folks like to believe that good pictures show much of what is interesting about data; this series of posts will carve a path from graph data to good graph plots. The path will take us mostly through well-known research results and techniques; the trick here is I will try to motivate the choices from first principles, or at least as close to it as I can manage.
One of the ideas I hope to get across is that, when designing a visualization, it pays to systematically consider the design space. Jock MacKinlay’s 1986 real breakthrough was not the technique for turning a relational schema into a drawing specification. It was the realization that this systematization was possible and desirable. That his technique was formal enough to be encoded in a computer program is great gravy, but the basic insight is deeper.
Of course, the theory and practice of visualization in general is not ready for a complete systematization, but there are portions ripe for the picking. In this series, I want to see what I can do about graph visualization.
If you like this introduction, be sure to follow the series to:
So you want to look at a graph, part 1
This series of posts is a tour through of the design space of graph visualization. As I promised, I will do my best to objectively justify as many visualization decisions as I can. This means we will have to go slow; I won’t even draw anything today! In this post, I will only take the very first step: all we will do is think about graphs, and what might be interesting about them.
So you want to look at a graph, part 2
This series of posts is a thorough examination of the design space of graph visualization (Intro, part 1). In the previous post, we talked about graphs and their properties. We will now talk about constraints arising from the process of transforming our data into a visualization.
So you want to look at a graph, part 3
This series of posts is a tour of the design space of graph visualization. I’ve written about graphs and their properties, and how the encoding of data into a visual representation is crucial. In this post, I will use those ideas to justify the choices behind a classic algorithm for laying out directed, mostly-acyclic graphs.
More posts are coming!
So you want to look at a graph? I think the reality is that most people will answer no to that question (even if the graph looks cool). Graphs just take too much mental effort to figure out what they really mean. In the physical, social, or computer world, how many graph based interfaces have been successful versus hierarchies and/or tables? Books have been popular for over 500 years and we still present the reference graph as a tree of lists at the back of the book. Given the popularity of trees, lists, and tables, I keep thinking there must be a good way to present graph data in those formats to make it more understandable.
Comment by clemp — April 24, 2013 @ 9:16 pm
There’s a contrary view! 😉
As a text person I have a lot of sympathy for your point.
On the other hand, people have been picking out “meaningful” patterns from the night sky for quite some time. I wonder if testing subjects with night sky photos and what they see would have some relationship to how well they use graph visualizations?
What would underlie such a difference in perception I don’t know but it could be important for designing customizable interfaces.
I rather like graphs as information structures but that isn’t the same thing as saying a really busy graph is useful to me for analytical purposes.
I suppose that may be the next frontier, customizable interfaces.
Printed books have only one presentation because of the limits of their technology. Interesting that we have duplicated that limitation in an environment that doesn’t require it. 😉
Comment by Patrick Durusau — April 26, 2013 @ 5:27 am
I agree that *some* people have been picking out meaningful patterns but I would guess that 95% of the population could not find more than one of them (me included). When you apply that to computers, I guess it’s a question of whether one is targeting an application at the 5% or the 95%.
With book indexes, surely we could have developed another form after the inclusion of illustrations but we didn’t. Is there a reason we didn’t? I would guess that some publishers tried but it just did not catch on. Graphs are great as information structures but they just don’t seem to be very good for presentation of the information for most people (otherwise they would be more popular).
Even if we restrict the discussion to computer technology, successful presentation of information graphs seem to be rare so my conclusion was that most people would rather not look at a graph when trying to manage information. Here are some examples of presentations of complex information that have become popular.
File Managers – Trees
(Symlinks or Shortcuts added to represent graph in a tree form)
Mind Mapping – Trees
Outliner – Trees
Word Processor – Lists, Trees, and Tables
Spreadsheet – Tables
SQL Database – Tables.
Reports added to present information that is more complex than
a table.
WWW – Graph is invisible with only link labels being shown.
Maybe it is just that we don’t have a good way to present the structure of the graph yet and that is the problem. All of the above provide some structure in the presentation of information but force directed graphs do not. When graphs are structured (like a map), they seem to be much more understandable. For example, subway maps are in wide use in the real world. Maybe that’s a good format for presenting graphs?
http://www.scimaps.org/maps/map/phd_thesis_map_94/
These could still be very complex but not as impenetrable as the usual force directed graph.
http://www.scimaps.org/maps/map/mapa_fisiologico_del_68/
Topic Maps seem like they can provide semantics for the rest of us but they are still missing the a good way to present that rich information to the rest of us.
Comment by clemp — April 26, 2013 @ 9:33 am
I want tee off from your last comment: “Topic Maps seem like they can provide semantics for the rest of us but they are still missing the a good way to present that rich information to the rest of us.”
I like you example of the subway map. If I were writing a topic map of crime on a subway system, it would likely be displayed as a subway map with locations.
I think the general point should be that topic maps have no fixed display but can be displayed in whatever manner is the best display for a particular use case.
Another example and I don’t have the cite handy, was a topic map of artistic artifacts from history that was displayed to the end user as HTML pages. The Tax Map is another example of where a topic map drives a more traditional text display.
Comment by Patrick Durusau — April 29, 2013 @ 8:55 am