Nichole Stockman | MAT259: Visualizing Data | Winter 2011

Project 2: Top 100 Most Checked Out Items from 2005 to 2010



This project takes the 100 items with the highest total number of checkouts between 2005 and 2010 and displays them as a treemap. In the initial view, the actual items are occluded and only boxes representing the relative categories are shown. This gives the user an immediate overview of which categories are the most popular (if we assume popularity is simply a measure of how many times an item has been checked out).

The user is then able to interact with the treemap to extract more information. Left clicks will display the contents of a category or zoom in to that category. Right clicks have the reverse effect. An box pops up to display information about whichever item the mouse is hovering over in order to present more detailed information to the user, but this can easily be toggled by pressing the 'i' button.

The size of each square is directly determined by the number of checkouts for that item or category, whichever is currently being displayed. The brightness for squares representing items corresponds to whether the item is a CD, DVD or book.


This project uses an XML dataset stored in a mySQL database containing information on checked-out items (books, cds, movies, etc.) from the Seattle Public Library. The data has been continuously recorded since August, 2005 and includes information from earlier dates.

  • Left Click to show a square's contents or zoom in to a category.
  • Right Click to hide contents or zoom out.
  • Press 'i' to toggle display of the information box.

  • Visualization:
    Source Code: