Digital library search results are usually shown as a textual list, with 10-20 items per page. Viewing several thousand search results at once on a two-dimensional display with continuous variables is a promising alternative. Since these displays can overwhelm some users, we created GRIDL, a two-dimensional display that uses categorical and hierarchical axes, called hieraxes. Users click on labels to move down a level in the hierarchy. The related papers listed below discuss alternative designs for handling broad hierarchies and arranging for imposed hierarchies. Strengths and weaknesses uncovered during a preliminary usability study are also discussed.
GRIDL has been applied to a digital library of science topics used by middle school teachers, a legal information system, and a technical library using the ACM Computing Classification System. Demos of each are available below.
Demos:
Multimedia Science Resources for Middle SchoolsData File Format: (Example Data File)
GRIDL reads data from tab-delimitated ASCII files where:
Line 1: Attribute NamesLine 2: Attribute Types
Lines 3-n: Data Records
- Currently the only valid attribute type is STRING. By default, all attributes in your dataset may be displayed on the axes and used for color-coding. However, not all attributes may be appropriate for these purposes. For example, a narrative description would not be appropriate for displaying on the axes or color-coding. If you do not wish to allow an attribute to be displayed on the axes or to be used for color-coding, place a '*' after the attribute type (e.g., STRING*). If you wish to allow an attribute to be displayed on the axes but NOT used as a color option, place a '+' after the attribute type (e.g., STRING+).
- To indicate that an attribute is hierarchical, append ':HIER#' to the attribute type where # is the number of levels in the hierarchy. For example, 'STRING+:HIER2' is a two level string hierarchy that can be displayed on the x and y axes.
- A hierarchy for a given data record should be of the form: '{level1:::level2:::level#}'.
- Blank data values (e.g., "") are not allowed and should be indicated with '**null**' (this is also true for hierarchical values).
Applet Parameters: (Example HTML File)
GRIDL recognizes the following applet parameters:
| Parameter | Description |
| data | Name of data file |
| xaxis | Name of attribute to display on xaxis (first attribute used if not specifed) |
| yaxis | Name of attribute to display on yaxis (first attribute used if not specified) |
| colorby | Name of attribute to use for color-coding |
| labelby | Name of attribute to display in result list when user clicks on grid of dots or bar chart (first attribute used if not specified) |
| labelby2 | Name of attribute to display in result list of 'labelby' is **null** |
Implementation Notes:
| Overview | Overview of GRIDL package |
| GRIDL | Brief roadmap for following the flow of what is going on |
| Controller | General description of main applet class (GRIDLApplet.class) |
| Database | Generic database classes used to store data |
| Hieraxis | Notes about classes used to implement hieraxes |
| Model | Notes about classes used to parse data file and manipulate loaded data |
| UI | Notes about classes used to implement GRIDL user interface |
Related Papers:
99-03
Shneiderman, B., Feldman, D., Rose, A., and Ferre Grau, X. (February 1999)
Visualizing
Digital Library Search Results with Categorical and Hierarchial Axes
CS-TR-3992, UMIACS-TR-99-12, ISR-TR-99-75
Proc. 5th ACM International Conference on Digital Libraries (San Antonio, TX,
June 2-7, 2000), ACM, New York, 57-66.
97-15
Rose, A., Ding, W., Marchionini, G., Beale Jr., J., Nolet, V. (1997)
Building
an Electronic Learning Community: From Design to Implementation
CS-TR-3831, UMIACS-TR-97-67,CLIS-TR-97-12
Proceedings of CHI 98, Los Angeles, CA, 18-23 April 1998, ACM, New York,
203-210