This paper is concerned with the problem of structured data extraction from Web pages. The objective of the research is to automatically segment data records in a page, extract data items/fields from these records and store the extracted data in a database. In this paper, we first introduce the extraction problem, and then discuss the main existing approaches and their limitations. After that, we introduce a novel technique (called DEPTA) to automatically perform Web data extraction. The method consists of three steps: (1) identifying data records with similar patterns in a page, (2) aligning and extracting data items from the identified data records and (3) generating tree-based regular expressions to facilitate later extraction from other similar pages. The key innovation is the proposal of a new multiple tree alignment algorithm called partial tree alignment, which was found to be particularly suitable for Web data extraction. This paper is based on our work published in KDD-03 and WWW-05.
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