How can I visualize hierarchical data?

Question

I have some data like the following:

A A1 12
A A2 23
A A3 AA1 1
A A3 AA2 2
B B1 2
B B2 1

Is there a way to visualize this information in ggplot? I am looking for something like this:

   |--A1---12
   |--A2---23
A--|--A3--AA1--1
      |---AA2--2

B--|--B1---2
   |--B2---1

Any suggestions?

Answer 1

Take a look at Rgraphviz, which can allow you to visualize graphs (including trees), using different schemes for your nodes.

Answer 2

Are you set on using ggplot? Personally, I would not process this kind of data in R since it's not really of statistical nature. I would rather write a python script to build a tree/forest, and view it using one of the many excellent graph visualization tools out there, e.g. Gephi.