MAT 259 - 2008W

Michael McDaniel - Dewey Trends*

Project Description

The motivation behind this project was to create a practical yet aesthetically pleasing and complex interactive data visualization. This visualization allows the user to compare the checkout activity of multiple Dewey decimal subjects as well as understand specific checkout patterns of single Dewey subjects.

The color gradients on the left of the screen provide a unique and intuitive method of data access. As the user rolls over these gradient bars they are provided with the Dewey subjects number (below the bars) as well as the pattern of checkout activity in the graph area to the right. This interaction allows the user to find specific patterns of checkout activity.

Clicking on the bars draws the given subject activity to the graph. Rolling over the graph itself allows the user to access detailed information about the checkout activity of the subject. This detailed information includes the date, time and volume of checked out items for the month of January 2008.

Holding down the shift key while clicking on the bars draws a second Dewey subject to the graph allowing the user to compare the activity of different subjects. With caps lock engaged the second graph will remain on the screen to further facilitate this comparison.

Design Choices


In order to create the most diversity in color between the ten Dewey classes I set the color mode of the visualization to HSB (hue, saturation, brightness) with hue values ranging from 1 - 10 (determined by primary class), saturation ranging from 0 -99 (determined by each subjects location within the classes) and a brightness value set at 100. The black background allows for the greatest contrast between the data and the negative space, focusing the user on the information itself.

Type + Text

Helvetica Neue Bold is the only typeface used in the visualization. It is a neutral and legible typeface that does not command attention allowing the information to be the main focus of the display. Minimal text is used. Only a title, Dewey subject numbers and subject titles, along with temporal and volume information are displayed. Again, only necessary text is used as to not distract from the information.


The logarithmic scale might be confusing for some users but is necessary in order to illustrate low activity rates. Also, this visualization is most useful for understanding qualitative differences between subjects rather than quantitative differences, though quantitative data can be easily understood for single subjects.

Project Data
Zip archive* (2.0M)

* The applet version of this project takes a very long time to load due to the large size of the data file being accessed. Downloading the archived project and running the program locally is probably the fastest way to view the project.

Screen Shots
loading data
parsing data
empty graph
roll over bars
select dewey number, hover over graph
dewey number selected, holding down shift, comparing two subjects
two subjects on graph, rolling over bars
comparing two subjects from first project
first project, same data and subjects as above