Dynamic Queries cs 5984 Information Visualization Chris North

Dynamic Queries cs 5984: Information Visualization Chris North

Assignment • Read for Tues: • Roth, “Visage”, web (video) » josh, priya • North, “Snap-Together Visualization”, web • Multiple Views

Assignment • Read for Thurs • Plaisant, “Lifelines”, p 285 » chris r. , margaret • Mackinlay, “Perspective Wall”, web » sumithra, gowri • Read for next tues • Eick, “See. Soft”, p 419 » purvi, prasuna • Eick, “Data Visualization Sliders”, p 251 (2 pages) • Homework #1 due Monday 5 pm

Home. Finder

Spotfire

Limitations • Scale: • Scatterplot screen space: 10, 000 – 1, 000 • Data structures & algorithms: 50, 000 – 1, 000 – Poor screen drawing on Filter out • A Solution: Query Previews! • AND queries only • Arbitrary boolean queries? • A solution: Filter Flow • Another solution: Magic Lens

DQ Algorithm • Idea: incremental algorithm, only deal with data items that change state • When slider moves: • Calculate slider delta • Search in data structure for data items in the delta region • If slider moved inward (filter out): – Erase data items from visualization • Else (filter in): – Draw data items on visualization Problem! Overlapped items, erases items underneath too

DQ Data Structures • Sorted array of the data for each slider • Need counter for each data item = # sliders that filter it • Multi-dimensional data structure • E. g. : K-d tree • Recursively split space • Enables fast range search

Filter-Flow

Today • Fishkin, “Movable filters” (Magic Lens), p 253 » prasuna, umer • Doan, “Query Previews”, web page » aarthi, ameya

Review • Many attributes: • Many items: • Very Many items: • Hard! Why? • Can’t show everything, interaction is key