Web Data Extraction Based on Partial Tree Alignment

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Zhai, Y., Liu, B.: Web data extraction based on partial tree alignment. In: WWW. (2005) 76–85.

Online version



This paper studies the problem of extracting data from semi-structured web pages which has been widely studied in information extraction community. Most of the techniques in extracting structured information from the Web are limited by either of the following two limitations: they require human labeling of many web pages or they have made many assumptions that are not applicable to many web sites.

This paper presents a novel technique which doesn't have the above limitations. The method has two phases: 1- identifying data fields in the input web page, and 2- extracting data from the identified data fields. To identify data fields in the web page they have used MDR algorithm which is presented in detail in [1]. After identifying appropriate fields in the given web page, they have used partial tree alignment technique to extract data from each field.

The main differences between this paper and the method that is presented in MDR algorithm are the followings:

- They have improved MDR algorithm using visual information to be able to identify individual data records more accurately.

- They have also proposed a new technique to extract content of each data field based on tree matching techniques.

They have tested their systems on different websites. They have shown the recall result of their method is about 98.18% and have obtained precision of 99.68%.


[1] Liu, B., Grossman, R. and Zhai, Y. “Mining data records from Web pages.” KDD-03, 2003.