Wednesday, January 5, 2022

Holiday fun...

 Aloha and a happy new year...

I took the first week of 2022 off and because I love coding I was looking for something that I might add to one of my libraries.

It was not too hard to find something interesting and I decided to give it a try...the Radial Tidy Tree...

For those of you that have no idea what I am talking is a little example from the web...

It is a tree structure that is visualized using a radial layout.

Looks like a fun thing to do but it really gave me some time to get it right. First of all (as nearly always) I had no real use case for it but just wanted to be able to create a chart like that.

So I decided to simply visualize a year. The root node has 4 child nodes, the 4 quarters and each quarter has 3 child nodes, the months of each quarter. Finally each month has it's specific number of days.

That's not real useful data but at least you can use it to create a Radial Tidy Tree. In principle it looks like an easy task but there are some things that are not that easy to solve. 

First of all you have to create the tree structure which is easy using my TreeNode class which I already used for the Sunburst chart. For this one I had to add more properties to it like x, y and angle. Thanks to the java.time package the creation of the tree was easy.

I won't show all the code here but if you like you can simply head over to github and check it out there...

The really tricky part was figuring out the angle step between the items on each level and I tried different approaches before I finally found a way that worked for me. 

Once I was able to place the items in the right place the next thing was to create all the bezier curves between the items to make it look good. And the last step was to put the text in the right position and rotate it correctly.

Well...long story is the result...

And I really like the way the result looks :)

As I already mentioned, I do not have a real use case for it and therefor I cannot guarantee that the tree will work for all use cases. But I did a few other tests and it seems to be ok.

The RadialTidyTree can be found in the latest release of my charts library (17.1.2) which you can either get on github or on maven central.

As with all the charts in my charts library you can find a class that shows how to use it in the test package, for this one just look for

And that's keep coding... :)

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