Document classification

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Document classification or document categorization is a problem in library science, information science and computer science. The task is to assign a document to one or more classes or categories. This may be done "manually" (or "intellectually") or algorithmically. The intellectual classification of documents has mostly been the province of library science, while the algorithmic classification of documents is mainly in information science and computer science. The problems are overlapping, however, and there is therefore interdisciplinary research on document classification.

Contents

The documents to be classified may be texts, images, music, etc. Each kind of document possesses its special classification problems. When not otherwise specified, text classification is implied.

Documents may be classified according to their subjects or according to other attributes (such as document type, author, printing year etc.). In the rest of this article only subject classification is considered. There are two main philosophies of subject classification of documents: the content-based approach and the request-based approach.

"Content-based" versus "request-based" classification

Content-based classification is classification in which the weight given to particular subjects in a document determines the class to which the document is assigned. It is, for example, a common rule for classification in libraries, that at least 20% of the content of a book should be about the class to which the book is assigned. [1] In automatic classification it could be the number of times given words appears in a document.

Request-oriented classification (or -indexing) is classification in which the anticipated request from users is influencing how documents are being classified. The classifier asks themself: “Under which descriptors should this entity be found?” and “think of all the possible queries and decide for which ones the entity at hand is relevant” (Soergel, 1985, p. 230 [2] ).

Request-oriented classification may be classification that is targeted towards a particular audience or user group. For example, a library or a database for feminist studies may classify/index documents differently when compared to a historical library. It is probably better, however, to understand request-oriented classification as policy-based classification: The classification is done according to some ideals and reflects the purpose of the library or database doing the classification. In this way it is not necessarily a kind of classification or indexing based on user studies. Only if empirical data about use or users are applied should request-oriented classification be regarded as a user-based approach.

Classification versus indexing

Sometimes a distinction is made between assigning documents to classes ("classification") versus assigning subjects to documents ("subject indexing") but as Frederick Wilfrid Lancaster has argued, this distinction is not fruitful. "These terminological distinctions,” he writes, “are quite meaningless and only serve to cause confusion” (Lancaster, 2003, p. 21 [3] ). The view that this distinction is purely superficial is also supported by the fact that a classification system may be transformed into a thesaurus and vice versa (cf., Aitchison, 1986, [4] 2004; [5] Broughton, 2008; [6] Riesthuis & Bliedung, 1991 [7] ). Therefore, the act of labeling a document (say by assigning a term from a controlled vocabulary to a document) is at the same time to assign that document to the class of documents indexed by that term (all documents indexed or classified as X belong to the same class of documents). In other words, labeling a document is the same as assigning it to the class of documents indexed under that label.

Automatic document classification (ADC)

Automatic document classification tasks can be divided into three sorts: supervised document classification where some external mechanism (such as human feedback) provides information on the correct classification for documents, unsupervised document classification (also known as document clustering), where the classification must be done entirely without reference to external information, and semi-supervised document classification, [8] where parts of the documents are labeled by the external mechanism. There are several software products under various license models available. [9] [10] [11] [12] [13] [14]

Techniques

Automatic document classification techniques include:

Applications

Classification techniques have been applied to

See also

Related Research Articles

Information retrieval (IR) in computing and information science is the task of identifying and retrieving information system resources that are relevant to an information need. The information need can be specified in the form of a search query. In the case of document retrieval, queries can be based on full-text or other content-based indexing. Information retrieval is the science of searching for information in a document, searching for documents themselves, and also searching for the metadata that describes data, and for databases of texts, images or sounds.

<span class="mw-page-title-main">Library classification</span> Systems of coding and organizing documents or library materials

A library classification is a system used within a library to organize materials, including books, sound and video recordings, electronic materials, etc., both on shelves and in catalogs and indexes. Each item is typically assigned a call number, which identifies the location of the item within the system. Materials can be arrange by many different factors, typically in either a hierarchical tree structure based on the subject or using a faceted classification system, which allows the assignment of multiple classifications to an object, enabling the classifications to be ordered in many ways.

<span class="mw-page-title-main">Glossary of library and information science</span>

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Automatic summarization is the process of shortening a set of data computationally, to create a subset that represents the most important or relevant information within the original content. Artificial intelligence algorithms are commonly developed and employed to achieve this, specialized for different types of data.

A faceted classification is a classification scheme used in organizing knowledge into a systematic order. A faceted classification uses semantic categories, either general or subject-specific, that are combined to create the full classification entry. Many library classification systems use a combination of a fixed, enumerative taxonomy of concepts with subordinate facets that further refine the topic.

<span class="mw-page-title-main">Medical Subject Headings</span> Controlled vocabulary

Medical Subject Headings (MeSH) is a comprehensive controlled vocabulary for the purpose of indexing journal articles and books in the life sciences. It serves as a thesaurus that facilitates searching. Created and updated by the United States National Library of Medicine (NLM), it is used by the MEDLINE/PubMed article database and by NLM's catalog of book holdings. MeSH is also used by ClinicalTrials.gov registry to classify which diseases are studied by trials registered in ClinicalTrials.

In statistics, classification is the problem of identifying which of a set of categories (sub-populations) an observation belongs to. Examples are assigning a given email to the "spam" or "non-spam" class, and assigning a diagnosis to a given patient based on observed characteristics of the patient.

Controlled vocabularies provide a way to organize knowledge for subsequent retrieval. They are used in subject indexing schemes, subject headings, thesauri, taxonomies and other knowledge organization systems. Controlled vocabulary schemes mandate the use of predefined, preferred terms that have been preselected by the designers of the schemes, in contrast to natural language vocabularies, which have no such restriction.

<span class="mw-page-title-main">Automatic image annotation</span>

Automatic image annotation is the process by which a computer system automatically assigns metadata in the form of captioning or keywords to a digital image. This application of computer vision techniques is used in image retrieval systems to organize and locate images of interest from a database.

<span class="mw-page-title-main">Outline of library and information science</span> Overview of and topical guide to library science

The following outline is provided as an overview of and topical guide to library and information science:

Sentiment analysis is the use of natural language processing, text analysis, computational linguistics, and biometrics to systematically identify, extract, quantify, and study affective states and subjective information. Sentiment analysis is widely applied to voice of the customer materials such as reviews and survey responses, online and social media, and healthcare materials for applications that range from marketing to customer service to clinical medicine. With the rise of deep language models, such as RoBERTa, also more difficult data domains can be analyzed, e.g., news texts where authors typically express their opinion/sentiment less explicitly.

Knowledge organization (KO), organization of knowledge, organization of information, or information organization is an intellectual discipline concerned with activities such as document description, indexing, and classification that serve to provide systems of representation and order for knowledge and information objects. According to The Organization of Information by Joudrey and Taylor, information organization:

examines the activities carried out and tools used by people who work in places that accumulate information resources for the use of humankind, both immediately and for posterity. It discusses the processes that are in place to make resources findable, whether someone is searching for a single known item or is browsing through hundreds of resources just hoping to discover something useful. Information organization supports a myriad of information-seeking scenarios.

Subject indexing is the act of describing or classifying a document by index terms, keywords, or other symbols in order to indicate what different documents are about, to summarize their contents or to increase findability. In other words, it is about identifying and describing the subject of documents. Indexes are constructed, separately, on three distinct levels: terms in a document such as a book; objects in a collection such as a library; and documents within a field of knowledge.

A Web query topic classification/categorization is a problem in information science. The task is to assign a Web search query to one or more predefined categories, based on its topics. The importance of query classification is underscored by many services provided by Web search. A direct application is to provide better search result pages for users with interests of different categories. For example, the users issuing a Web query "apple" might expect to see Web pages related to the fruit apple, or they may prefer to see products or news related to the computer company. Online advertisement services can rely on the query classification results to promote different products more accurately. Search result pages can be grouped according to the categories predicted by a query classification algorithm. However, the computation of query classification is non-trivial. Different from the document classification tasks, queries submitted by Web search users are usually short and ambiguous; also the meanings of the queries are evolving over time. Therefore, query topic classification is much more difficult than traditional document classification tasks.

Automatic indexing is the computerized process of scanning large volumes of documents against a controlled vocabulary, taxonomy, thesaurus or ontology and using those controlled terms to quickly and effectively index large electronic document depositories. These keywords or language are applied by training a system on the rules that determine what words to match. There are additional parts to this such as syntax, usage, proximity, and other algorithms based on the system and what is required for indexing. This is taken into account using Boolean statements to gather and capture the indexing information out of the text. As the number of documents exponentially increases with the proliferation of the Internet, automatic indexing will become essential to maintaining the ability to find relevant information in a sea of irrelevant information. Natural language systems are used to train a system based on seven different methods to help with this sea of irrelevant information. These methods are Morphological, Lexical, Syntactic, Numerical, Phraseological, Semantic, and Pragmatic. Each of these look and different parts of speed and terms to build a domain for the specific information that is being covered for indexing. This is used in the automated process of indexing.

International Aging Research Portfolio (IARP) is a non-profit, open-access knowledge management system incorporating grants, publications, conferences in natural and social & behavioral sciences. In addition to the advanced search and visual trend analysis tools the system includes a directory of research projects classified into categories related to aging research. The system uses automatic classification algorithms with elements of machine learning to assign research projects to the relevant categories. The directory is curated by many expert category editors and science advisory board members. The chair of the science advisory board is Dr. Charles Cantor.

Multimedia information retrieval is a research discipline of computer science that aims at extracting semantic information from multimedia data sources. Data sources include directly perceivable media such as audio, image and video, indirectly perceivable sources such as text, semantic descriptions, biosignals as well as not perceivable sources such as bioinformation, stock prices, etc. The methodology of MMIR can be organized in three groups:

  1. Methods for the summarization of media content. The result of feature extraction is a description.
  2. Methods for the filtering of media descriptions
  3. Methods for the categorization of media descriptions into classes.

Concept-based image indexing, also variably named as "description-based" or "text-based" image indexing/retrieval, refers to retrieval from text-based indexing of images that may employ keywords, subject headings, captions, or natural language text. It is opposed to Content-based image retrieval. Indexing is a technique used in CBIR.

Jack Mills was a British librarian and classification researcher, who worked for more than sixty years in the study, teaching, development and promotion of library classification and information retrieval, principally as a major figure in the British school of facet analysis which builds on the traditions of Henry E. Bliss and S.R. Ranganathan.

The following outline is provided as an overview of and topical guide to natural-language processing:

References

  1. ↑ Library of Congress (2008). The subject headings manual. Washington, DC.: Library of Congress, Policy and Standards Division. (Sheet H 180: "Assign headings only for topics that comprise at least 20% of the work.")
  2. ↑ Soergel, Dagobert (1985). Organizing information: Principles of data base and retrieval systems. Orlando, FL: Academic Press.
  3. ↑ Lancaster, F. W. (2003). Indexing and abstracting in theory and practice. Library Association, London.
  4. ↑ Aitchison, J. (1986). "A classification as a source for thesaurus: The Bibliographic Classification of H. E. Bliss as a source of thesaurus terms and structure." Journal of Documentation, Vol. 42 No. 3, pp. 160-181.
  5. ↑ Aitchison, J. (2004). "Thesauri from BC2: Problems and possibilities revealed in an experimental thesaurus derived from the Bliss Music schedule." Bliss Classification Bulletin, Vol. 46, pp. 20-26.
  6. ↑ Broughton, V. (2008). "A faceted classification as the basis of a faceted terminology: Conversion of a classified structure to thesaurus format in the Bliss Bibliographic Classification (2nd Ed.).]" Axiomathes, Vol. 18 No.2, pp. 193-210.
  7. ↑ Riesthuis, G. J. A., & Bliedung, St. (1991). "Thesaurification of the UDC." Tools for knowledge organization and the human interface, Vol. 2, pp. 109-117. Index Verlag, Frankfurt.
  8. ↑ Rossi, R. G., Lopes, A. d. A., and Rezende, S. O. (2016). Optimization and label propagation in bipartite heterogeneous networks to improve transductive classification of texts. Information Processing & Management, 52(2):217–257.
  9. ↑ "An Interactive Automatic Document Classification Prototype" (PDF). Archived from the original (PDF) on 2017-11-15. Retrieved 2017-11-14.
  10. ↑ Interactive Automatic Document Classification Prototype Archived April 24, 2015, at the Wayback Machine
  11. ↑ Document Classification - Artsyl
  12. ↑ ABBYY FineReader Engine 11 for Windows
  13. ↑ Classifier - Antidot
  14. ↑ "3 Document Classification Methods for Tough Projects". www.bisok.com. Retrieved 2021-08-04.
  15. ↑ Stephan Busemann, Sven Schmeier and Roman G. Arens (2000). Message classification in the call center. In Sergei Nirenburg, Douglas Appelt, Fabio Ciravegna and Robert Dale, eds., Proc. 6th Applied Natural Language Processing Conf. (ANLP'00), pp. 158–165, ACL.
  16. ↑ Santini, Marina; Rosso, Mark (2008), Testing a Genre-Enabled Application: A Preliminary Assessment (PDF), BCS IRSG Symposium: Future Directions in Information Access, London, UK, pp. 54–63, archived from the original (PDF) on 2019-11-15, retrieved 2011-10-21{{citation}}: CS1 maint: location missing publisher (link)
  17. ↑ X. Dai, M. Bikdash and B. Meyer, "From social media to public health surveillance: Word embedding based clustering method for twitter classification," SoutheastCon 2017, Charlotte, NC, 2017, pp. 1-7. doi : 10.1109/SECON.2017.7925400
  18. ↑ Krallinger, M; Leitner, F; Rodriguez-Penagos, C; Valencia, A (2008). "Overview of the protein-protein interaction annotation extraction task of Bio Creative II". Genome Biology. 9 (Suppl 2): S4. doi: 10.1186/gb-2008-9-s2-s4 . PMC   2559988 . PMID   18834495.

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