Journal IssueDOI
The relation between Pearson's correlation coefficient r and Salton's cosine measure
Leo Egghe,Loet Leydesdorff +1 more
TLDR
The relation between Pearson's correlation coefficient and Salton's cosine measure is revealed based on the different possible values of the division of the L1-norm and the L2-norm of a vector, resulting in a sheaf of increasingly straight lines which together form a cloud of points, being the investigated relation.Abstract:
The relation between Pearson's correlation coefficient and Salton's cosine measure is revealed based on the different possible values of the division of the L1-norm and the L2-norm of a vector. These different values yield a sheaf of increasingly straight lines which together form a cloud of points, being the investigated relation. The theoretical results are tested against the author co-citation relations among 24 informetricians for whom two matrices can be constructed, based on co-citations: the asymmetric occurrence matrix and the symmetric co-citation matrix. Both examples completely confirm the theoretical results. The results enable us to specify an algorithm that provides a threshold value for the cosine above which none of the corresponding Pearson correlations would be negative. Using this threshold value can be expected to optimize the visualization of the vector space. © 2009 Wiley Periodicals, Inc.read more
Citations
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Journal IssueDOI
A global map of science based on the ISI subject categories
Loet Leydesdorff,Ismael Rafols +1 more
TL;DR: The nested maps of science are online at .
Posted Content
A Global Map of Science Based on the ISI Subject Categories
Loet Leydesdorff,Ismael Rafols +1 more
TL;DR: The nested maps of science (corresponding to 14 factors, 172 categories, and 6,164 journals) are brought online and an analysis of interdisciplinary relations is pursued at three levels of aggregation using the newly added ISI subject category of "Nanoscience & nanotechnology".
Posted Content
The Use of Machine Learning Algorithms in Recommender Systems: A Systematic Review
TL;DR: In this paper, the authors present a systematic review of the literature that analyzes the use of machine learning algorithms in recommender systems and identifies research opportunities for software engineering research, and conclude that Bayesian and decision tree algorithms are widely used in recommendation systems because of their relative simplicity and that requirement and design phases of recommender system development appear to offer opportunities for further research.
Journal ArticleDOI
A deep-learning based feature hybrid framework for spatiotemporal saliency detection inside videos
TL;DR: Experimental results show that the proposed model outperforms five other state-of-the-art video saliency detection approaches and the proposed framework is found useful for other video content based applications such as video highlights.
Journal ArticleDOI
Interactive overlays: a new method for generating global journal maps from Web-of-Science data
Loet Leydesdorff,Ismael Rafols +1 more
TL;DR: In this article, the authors developed interactive overlays to a global map of science based on aggregated citation relations among the 9162 journals contained in the Science Citation Index (SCI) and Social Science Citation index (SciCEI) 2009.
References
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Book
Social Network Analysis: Methods and Applications
TL;DR: This paper presents mathematical representation of social networks in the social and behavioral sciences through the lens of Dyadic and Triadic Interaction Models, which describes the relationships between actor and group measures and the structure of networks.
Book
Introduction to Modern Information Retrieval
Gerard Salton,Michael J. McGill +1 more
TL;DR: Reading is a need and a hobby at once and this condition is the on that will make you feel that you must read.
Journal ArticleDOI
Co-citation in the scientific literature: A new measure of the relationship between two documents
TL;DR: A new form of document coupling called co-citation is defined as the frequency with which two documents are cited together, and clusters of co- cited papers provide a new way to study the specialty structure of science.
Journal ArticleDOI
An algorithm for drawing general undirected graphs
Tomihisa Kamada,Satoru Kawai +1 more