What are prefuse data groups and how do I put nodes into them?

Many components of prefuse seem to use a String group to identify some subset of data. How do you use groups in practice? Some documentation seems to imply that a single row of data can belong to multiple groups, but I cannot work out how to make this happen.

Ideally, I could put some nodes of a graph into multiple groups, but have them each visualized once, and apply various forces and layouts to them.

Indeed most prefuse components such as Layout, ColorAction or the RendererFactory use group names.

There are different types of groups:

• groups created from raw data, e.g. by vis.addGraph(...)
• focus groups that contains some items (= rows) from another group
• decorator groups, e.g., for labels
• aggregate groups that represent items merged to aggregated items

In order to put "some nodes of a graph into multiple groups" you can use focus groups. Then some Action may be added to run only on the focus group.

Alternatively you could pass a Predicate to the Action, so that only items (= rows) matching the Predicate are handled by the Action.

I recommend to look at the demos to see how this works: for example https://github.com/prefuse/Prefuse/blob/master/demos/prefuse/demos/ZipDecode.java