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TreeVersity:
Visualizing Changes Over Time
Using Dynamic Hierarchies

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TreeVersity2
TreeVersity2 thumbnail
  • Finds changes in multi-variate datasets over time.
  • Features the StemView, a visualization technique for representing up to five characteristics of change in trees.
TreeVersity (older version)
TreeVersity thumbnail
  • Compares two trees visualizing created and removed nodes, and node value changes.
  • Features the Bullet, a novel visualization glyph that allows the representation of four characteristics of change on tree nodes

Participants

John Alexis Guerra Gómez john.guerra{~at~}gmail.com
Under the supervision of: Catherine Plaisant and Ben Shneiderman {plaisant,ben} -at- cs.umd.edu
With the participation of Michael Pack form the CATT lab
And the design advice of: Audra Buck-Coleman buckcol3 -at- cs.umd.edu

Publications

Acknowledgements

TreeVersity2 was partially funded thanks to the support of the Fulbright Science and Technology Scholarship, the Center for Advanced Transportation Technology Laboratory and the Center for Integrated Transportation Systems Management (a Tier 1 Transportation Center at the University of Maryland)

Availability

Please contact Catherine Plaisant if you are interested in licensing TreeVersity or working with us on further development for specific applications.

Description of TreeVersity2

TreeVersity2 Visualizing changes in the US Federal Budget

TreeVersity2 explores change in trees over time. Users can use TreeVersity to analyze relative and absolute change over one variable in each node, as well as created and removed nodes. Moreover, analysts can use TreeVersity to compare non-inherently hierarchichal datasets, by grouping them by it's attributes. For example, users looking at the change on the number of movies watch, can build a hierarchy grouping by age ranges, then by gender and then by favorite music genre, and answer questions like "how has changed the number of terror movies watched by teenage girls in the last year?".

TreeVersity provides a set of tools to facilitate the comparison process that include:

  • Comparison algorithms that calculate the change over each node of the tree (internal and leaf nodes)
  • Two visualization techniques called Bullet and The StemView that represents the change in each node of the tree with controls for navigation and filtering
  • A reporting tool that searches for the most significant changes on the tree and displays them in a textual report linked to the visualizations

TreeVersity2 Visualizing changes in the US Federal Budget

Videos


Related work

Much work has been done on visualizing and exploring single tree structures; however, the problem of comparing two trees is significantly harder. We have identified and classified the following types of tree comparison:

  • Type 0: Topological differences between two trees where the nodes only contain a label. Example: Finding created, moved and removed topics between two versions of the TRB research publications hierarchical categorization system, without looking for number of papers.
  • Type 1: Positive and negative changes in leaf node values with aggregated values in the interior nodes (i.e. trees that can be visualized with a treemap[25]) and no changes in topology. Example: Comparing the change on the number of workers on the traffic agencies of the country, grouped by Agencies, Counties and Regions, given that no Agencies are created or removed.
  • Type 2: Positive and negative changes in leaves and interior node values with no changes in topology. Example: Comparing the salaries in the Department of Transportation’s organizational chart between two years, when no reorganization has occurred.
  • Type 3: Positive and negative changes in leaf node values with aggregated values in the interior nodes and with changes in topology. Example: Again finding changes in the TRB research publications hierarchical categorization system, but looking at changes in the number of papers published by topic and at created, removed nodes.
  • Type 4: Positive and negative changes in leaves and interior node values, with changes in topology. Example: Comparing the number of TRB’s website visits between two months using the file hierarchy as a natural organization. Some pages might be created or removed, and each page in the hierarchy has an independent number of visits.

Most of the previous work on the field has focused on Types 0, and Types 1 (for a more comprehensive listing please refer to our technical report), TreeVersity was designed to support tree comparison types 1 to 4.

TreeVersity tree comparison types diagram


TreeVersity (the older version introducing the Bullet

TreeVersity Interface

Comparing Trees is difficult. To address this, we present TreeVersity a new interactive visualization that gives users powerful tools to detect both node value changes and topological differences. TreeVersity uses dual comparison techniques (side-by-side and explicit differences) and tabular representations, to facilitate the understanding and navigation of the differences. TreeVersity's design employs carefully designed color palettes to show positive/negative, absolute, and relative value changes; shapes that preattentively show these changes; and novel graphical approaches that highlight created and removed nodes'

Videos

Previous Work:

Presentations:

  • HCIL Symposium, May 2011: LifeFlow: Understanding Millions of Event Sequences in a Million Pixels
    (Krist Wongsuphasawat, John Alexis Guerra Gómez, Hsueh-Chien Cheng, A. Zachary Hettinger, Catherine Plaisant, Ben Shneiderman) Slides

  • HCIL Symposium, May 2011: TreeVersity: Comparing Tree Structures by Topology and Node Attribute Values
    (John Alexis Guerra Gómez, Catherine Plaisant, Ben Shneiderman) Slides

  • Fulbright Science and Technology scholarship capstone seminar (poster), June 2011, Analyzing Incident Management Event Sequences with Interactive Visualization
    (John Alexis Guerra Gómez)

  • 6th International Symposium on Visualization in Transportation (August 2011) Visualization temporal events in traffic incidents
    (John Alexis Guerra Gómez)

  • IEEE VisWeek 2011 (accepted, to be presented in Oct 2011) Doctoral consortium presentation and poster,
    TreeVersity: Comparing Tree Structures by Topology and Node’s Attributes Differences
    (John Alexis Guerra Gómez)