README.md

union-find-inspector

A tree visualizer for inspecting Disjoint-Set (or Union-Find) data structure.

Why?

First for curiousity, for seeing in a human-friendly way how a tree built from a disjoint-set looks like. The array data upon which it relies isn't helpful for understanding its structure.

Second, to help any people out there who would want to modify the algorithm to their requirements.

Usage

You need Maven to build and execute the project. Download, install it and ensure the Maven binaries are available in your path (via the PATH environment variable for example). Once done, change directory in the root of this cloned project and execute:

mvn package

Then, change directory in the newly created target directory and execute the union-find-inspector-1.0.jar file. You can either double-click the jar file in Windows or via the command-line:

java -jar union-find-inspector-1.0.jar

File Formats

The visualizer supports two file formats to represent a disjoint-set data structure: a percolation entries file and an array of *IDs *file.

Percolation File (*.perc)

The percolation file contains the dimension and union instructions for the cell joins. It follows exactly the same format as the Algorithms, Part 1 Coursera class:

5
  1   2
  1   3
  3   1
  5   1
  2   3
  3   4
  4   1
  5   5
  4   5
  2   2
  3   3
  4   3
  5   3

The first line contains an integer that informs of the cell table dimension. In this case above, this would be a 5X5 table.

The following lines contains two coordinates on every line that indicates a union operation on the specified cells. The first coordinate is the X axis (horizontal) and the second one the Y axis (vertical).

IDs File (*.uf)

This file should have one line. The line should be a copy/paste of the Java debugger output of the disjoint-set array. It should look as the following:

[0,1,0,0,4,5,6,0,0,9,10,26,12,0,0,15,11,17,0,19,26,26,22,26,24,26,0]

Examples

Hyperbolic Tree

Treemap

Sunray Tree

Misc

Labels pop-ups will show the node hierarchy in the trees:

Coursera Students

You can plug-in your Percolation implementation into this visualizer, but it will need a few modifications. The modifications to perform:

1. Implement the IPercolation interface.
2. Change the package signature of your Percolation class from the default to org.jlr.percolation.
3. Name the WeightedQuickUnionUF class member to percolated.

Some of these restrictions could be eased or removed if there is demand. <:o)