Archive for the ‘Classification Trees’ Category

Constructing a true LCSH tree of a science and engineering collection

Monday, November 19th, 2012

Constructing a true LCSH tree of a science and engineering collection by Charles-Antoine Julien, Pierre Tirilly, John E. Leide and Catherine Guastavino.

Abstract:

The Library of Congress Subject Headings (LCSH) is a subject structure used to index large library collections throughout the world. Browsing a collection through LCSH is difficult using current online tools in part because users cannot explore the structure using their existing experience navigating file hierarchies on their hard drives. This is due to inconsistencies in the LCSH structure, which does not adhere to the specific rules defining tree structures. This article proposes a method to adapt the LCSH structure to reflect a real-world collection from the domain of science and engineering. This structure is transformed into a valid tree structure using an automatic process. The analysis of the resulting LCSH tree shows a large and complex structure. The analysis of the distribution of information within the LCSH tree reveals a power law distribution where the vast majority of subjects contain few information items and a few subjects contain the vast majority of the collection.

After a detailed analysis of records from the McGill University Libraries (204,430 topical authority records) and 130,940 bibliographic records (Schulich Science and Engineering Library), the authors conclude in part:

This revealed that the structure was large, highly redundant due to multiple inheritances, very deep, and unbalanced. The complexity of the LCSH tree is a likely usability barrier for subject browsing and navigation of the information collection.

For me the most compelling part of this research was the focus on LCSH as used and not as it imagines itself. Very interesting reading. A slow walk through the bibliography will interest those researching LCSH or classification more generally.

Demonstration of the power law with the use of LCSH makes one wonder about other classification systems as used.

Big-data Naive Bayes and Classification Trees with R and Netezza

Monday, March 19th, 2012

Big-data Naive Bayes and Classification Trees with R and Netezza

From the post:

The IBM Netezza analytics appliances combine high-capacity storage for Big Data with a massively-parallel processing platform for high-performance computing. With the addition of Revolution R Enterprise for IBM Netezza, you can use the power of the R language to build predictive models on Big Data.

In the demonstration below, Revolution Analytics’ Derek Norton analyzes loan approval data stored on the IBM appliance. You’ll see the R code used to:

  • Explore the raw data (with summary statistics and charts)
  • Prepare the data for statistical analysis, and create training and test sets
  • Create predictive models using classificiation trees and Na├»ve Bayes
  • Predict using the models, and evaluate model performance using confusion matrices

[embedded presentation omitted]

Note that while R code is being run on Derek’s laptop, the raw data is never moved from the appliance, and the analytic computations take place “in-database” within the appliance itself (where the Revolution R Enterprise engine is also running on each parallel core).

Another incentive for you to be learning R.

Does it sound to you like “Derek’s computer” is a terminal entering instructions that are executed elsewhere? ­čśë (If the computing fabric develops fast enough, we may lose the distinction of a “personal” computer. There will simply be computing.)

Meant to mention this the other day. Enjoy!