Cube Data
What is a closed cube
Closed cube is relatively new and very popular OLAP-cubes compression technique.It was first introduced in Quotient Cube algorithm by Laks V. S. Lakshmanan, Jian Pei and Jiawei Han. You can find my description of this algorithm in Russian here.
This concept was formalized in lattice theory terms by Casali, Cicchetti, Lakhal. Russian equivalent of this formalization + some extensions can be found here.
It's also used in C-Cubing algorithms, developed by IliMine team (lead by Jiawei Han).
How it works
Cubes are drawn using GraphViz (+ Pydot bindings since it's all python), this page is python cgi module + tempfiles for pictures.Cell colors are calculated using simple color code adding as aggregate. That's a huge problem, since there can be cases, when cell colors will mixup. For example
cell1 gets color#1, cell2 -- color2, then their aggregate color will be color1+color2, which can be assigned to another base cell.
To avoid that I calculate aggregate cells color as color[max(color) - color1+color2]. Need a better idea, it seems.