I enjoy toying with prime numbers and wanted to see how the Java GraphStream library worked. Here is a short video of the result.
Interestingly, it is little fun projects like this that often turn into moments of learning. While working on some prime number related programs I learned of some tool limits I wasn't aware of before this.
- The max radix value for converting numbers to strings is 36. From some searching, it sounds like that was chosen by being the number of values 0-9 + the 26 case-insensitive values a-z. I found it odd when numbers I converted starting at radix 37 were identical.
- Integer.toString(99999, 37)
- For a call to: com.google.common.collect.Sets.powerSet( aSet) , the "aSet" set parameter is limited to a max of 30 items.
I decided to try a variety of layout parameters to look for interesting results. Here are a few of those results using GraphStream.
Those were interesting but I decided to see if I could integrate different graphing libraries to look for other interesting features, etc.
My first attempt was to try integrating gephi but that didn't go well. As I looked into other graphing libraries, I noted that many are not maintained. This took way too much effort due to the version of netbeans libraries that had been used. I ended up forcing newer versions which are hosted by Apache. Eventually, I had code that built but no visual graph was produced - I noted some flakiness with one of my displays when trying to run it so I suspect an issue between older code and my display/drivers.
Next, I decided to try Jgrapht. This had an initial snag which was the fact that the original package was no longer maintained and wasn't available via maven. I ended up finding a version that is either a fork or repackaging of it and is available via maven. Now, things were much less difficult. It also resulted in very few total dependencies - even after I reworked the code significantly and added in the picocli lib for command line arg handling. I also ended up needing to add in the jgrapht-ext and jgraphx libs to display resulting graphs.
Here are a couple examples from that. The first uses the pre-canned compact tree layout. It took some playing to get something useful to display though. The second graph uses the pre-canned circle layout and that was easy to setup but still not as visually appealing as I desired.
I'll keep looking and trying new settings to see if I can come up with something better but this does work at least. From a visual graph standpoint, it doesn't scale very well it seems but maybe some tuning is possible. I got the generation of the primes tuned much better now and could generate 1M primes quickly but trying to graph even 10k primes seems unrealistic / painful. I'll probably end up terminating the running process before it ever gets to the point of displaying the graph.
[update] I added the ability to export my data into the Graph Modelling Language (GML) format and that is compatible with the yed tool. Yed has much richer layout support that what I have been working with from a Java library integration standpoint. The downside is that really large datasets are time consuming to visualize. I'm not sure how long it took for yed to complete this since I took a several hour break. This was for 10k primes.
