Extending Taxonomic Visualisations

Dealing with Large Datasets, Structural Markers and Synonymy

Large Datasets• Layout

• Datasets too large to display them in their entirety (in comparison to prev. work)

• Only layout partial trees • Top-down layout from current node of interest (anchor node) • Stop drilling down into branch when size of nodes below a threshold

• Various hierarchies displayed from top to bottom • Can be opened/closed

• Nodes as rectangles

• Node colored in top half if has been selected• Summary of user-selected descendants in lower half of node as bar chart• Size of node n by log(size(n))

Large Datasets• Brushing, Navigation and Selection

• Left-click re-roots tree at anchor node• Right-click selects subtree rooted at clicked node in all hierarchies (via

naming and/or synonymy)• Optionally re-rooting at clicked node• Least common ancestor if clicked node not found in other hierarchies

• Brushing temporarily on hover in same fashion as right-click select• Tooltip on hover

select

LCA

Large Datasets• Brushing, Navigation and Selection

• Left-click re-roots tree at anchor node• Right-click selects subtree rooted at clicked node in all hierarchies (via

naming and/or synonymy)• Optionally re-rooting at clicked node• Least common ancestor if clicked node not found in other hierarchies

• Brushing temporarily on hover in same fashion as right-click select• Tooltip on hover

• Text size, Focus & Context influence node size• Focus & Context ratio determines proportion of space allocated for selected

and not selected nodes

Large Datasets• Brushing, Navigation and Selection

• Left-click re-roots tree at anchor node• Right-click selects subtree rooted at clicked node in all hierarchies (via

naming and/or synonymy)• Optionally re-rooting at clicked node• Least common ancestor if clicked node not found in other hierarchies

• Brushing temporarily on hover in same fashion as right-click select• Tooltip on hover

• Text size, Focus & Context influence node size• Focus & Context ratio determines proportion of space allocated for selected

and not selected nodes

• Order in sibling groups may be changed• Alphabetically, by rank, by number of child taxa,…• Can help determine size distributions• Can help to find the highest rank within a group of child nodes

Structural Markers• Finding differences between tree revisions can be computationally expensive

• Depending on the actual type of change made• Whether exact locations are to be obtained

• Visualization requires cheap computation for large datasets

• Algorithm checks • Whether selected nodes keep same parent in other hiearchies compared to

original hierarchy. • Node is flagged as having had a change and consequently all ancestors up to

root node

• Flagged nodes are indicated in tree visualization • Hatched: Parent has changed between tree• Stripped: descendent set contains hatched node

Synonymy

Possible Future Work• Comparison of trees at multiple resolutions dependent on sub-tree size

• User could benefit from more information on structure change given by more computationally expensive algorithm used on a smaller set of nudes (subtree)

• Are users happy with this type of tree visualization?

• Any tasks users want to perform on the trees that are not covered?

• Synonymy can be given by expert articulations of Euler

Use Case: IT IS Dataset and Structural Markers

• 7 Taxonomy Revisions of dataset with each 180.00 – 250.000 taxa• Tasks

• Observe whether growth occurred between revisions and where growth is concentrated

• If taxa moved between revisions:• Did taxa’s siblings move in the same parent?• New parent otherwise unchanged?• New parent newly formed?

Use Case: IT IS Dataset and Structural Markers

• More problematic to discover a taxon that has undergone a purely internal revision.

Use Case: IT IS Dataset and Structural Markers