When comparing each Lego Set theme, it only felt natural to use a tree map such as the one above. Average theme pieces are encoded with each corresponding rectangle area and lightness. More general set themes tend to contain larger pieces, where specific topics tended to contain less parts. Lego uses three levels of themes in their sets. Level 1 is the main theme, level 2 is the sub theme, and level 3 is the sub-sub theme. Not all sets contain level 2 or level 3 themes so these were excluded from the tree map visualization for clarity.
