Whanhee Cho, Kuangfei Long, Mahmood Jasim, Matteo Brucato, Alexandra Meliou, Peter J. Haas, Anna Fariha
原文摘要
Selecting a bundle of items that collectively satisfies constraints is a fundamental task across databases, recommender systems, and text summarization. Unlike traditional retrieval that returns individual or top-k items, bundle retrieval is inherently combinatorial and, in general, NP-hard. Although package queries can efficiently retrieve bundles given a well-formed query, two key user-centric challenges remain: (1) expressing and tuning multi-dimensional bundle intent through a user-friendly interface, and (2) ensuring feasibility when the query yields empty results. We introduce Ex2Bundle, an Example-driven Bundle retrieval framework that enables users to specify their intent through example bundles and automatically synthesizes package queries that capture the intent implicit in those example bundles via aggregate constraints. Ex2Bundle also addresses a challenge unique to bundle retrieval: when inferred aggregate constraints are infeasible over the target data, our data-aware constraint relaxation minimally adjusts the constraint bounds while preserving alignment with user intent. We instantiate a specific application of focused text snippet extraction by example to demonstrate the efficacy of the Ex2Bundle framework. Extensive experiments over real-world datasets and a user study demonstrate that Ex2Bundle improves usability and consistently returns intent-aligned bundles even under distributional shifts of the target database.
Zafeiria Moumoulidou, Hamza Elhamdadi, Redwan Ahmed Rizvee, Ke Yang, Subrata Mitra, Cindy Xiong Bearfield, Alexandra Meliou
原文摘要
Analysts often use sampling in visual exploration to overcome the computational and perceptual bottlenecks of working with massive datasets. Yet, existing sampling methods optimize for statistical or geometric data properties, without explicit consideration for how humans perceive a visualization. We propose perception-augmented databases: a database framework that stores perceptual models of data as precomputed metadata and exposes a new query operator---perception-aware sampling---that selects subsets optimized for how humans visually perceive the result. We make the following contributions: (1) We introduce perception-augmented databases and design PAwS, a perception-aware sampling operator for scatterplot visualizations that leverages saliency maps---a computer vision tool for predicting areas of visual attention---combined with density and coverage objectives. (2) We design ApproPAwS: a fast approximate visualization method that works directly over a perception-aware compressed synopsis of the data, achieving up to 100x speed-ups with minimal loss in visual fidelity, and without accessing the underlying data at query time. (3) We contribute a perceptual similarity metric that evaluates the quality of a sample by comparing its saliency map to that of the original dataset, a novel evaluation methodology, applicable to any sampling method for scatterplots. (4) Our extensive experimental evaluation over datasets up to 3.5M points demonstrates that our methods consistently outperform five state-of-the-art sampling algorithms. A user study confirms that PAwS samples are preferred by humans, validating our quantitative findings.