Heatmap with subject and object grouped by directory

The heatmap groups the number of accesses in directory level and shows the number for cross directory access. The darker the color indicates more accesses.
We can easily sort the heatmap by frequency which give us the rank order of the most accesses directories.
In the order list, we can use different algorithm to calculate the relationship between each column and row as vectors and show the grouping result on heatmap.