Machine Learning for Data Mining 1

Department of Computer Science, University of Waikato, New Zealand

Eibe Frank

WEKA: A Machine Learning Toolkit

The Explorer• Classification and

Regression

• Clustering

• Association Rules

• Attribute Selection

• Data Visualization

The Experimenter

The Knowledge Flow GUI

Conclusions

Machine Learning with WEKA

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WEKA: the bird

Copyright: Martin Kramer (mkramer@wxs.nl)

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WEKA: the software

Machine learning/data mining software written in Java (distributed under the GNU Public License)

Used for research, education, and applications

Complements “Data Mining” by Witten & Frank

Main features: Comprehensive set of data pre-processing tools,

learning algorithms and evaluation methods

Graphical user interfaces (incl. data visualization)

Environment for comparing learning algorithms

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WEKA: versions There are several versions of WEKA:

WEKA 3.0: “book version” compatible with description in data mining book

WEKA 3.2: “GUI version” adds graphical user interfaces (book version is command-line only)

WEKA 3.3: “development version” with lots of improvements

This talk is based on the latest snapshot of WEKA 3.3 (soon to be WEKA 3.4)

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@relation heart-disease-simplified

@attribute age numeric@attribute sex { female, male}@attribute chest_pain_type { typ_angina, asympt, non_anginal, atyp_angina}@attribute cholesterol numeric@attribute exercise_induced_angina { no, yes}@attribute class { present, not_present}

@data63,male,typ_angina,233,no,not_present67,male,asympt,286,yes,present67,male,asympt,229,yes,present38,female,non_anginal,?,no,not_present...

WEKA only deals with “flat” files

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@relation heart-disease-simplified

@attribute age numeric@attribute sex { female, male}@attribute chest_pain_type { typ_angina, asympt, non_anginal, atyp_angina}@attribute cholesterol numeric@attribute exercise_induced_angina { no, yes}@attribute class { present, not_present}

@data63,male,typ_angina,233,no,not_present67,male,asympt,286,yes,present67,male,asympt,229,yes,present38,female,non_anginal,?,no,not_present...

WEKA only deals with “flat” files

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Explorer: pre-processing the data Data can be imported from a file in various

formats: ARFF, CSV, C4.5, binary

Data can also be read from a URL or from an SQL database (using JDBC)

Pre-processing tools in WEKA are called “filters”

WEKA contains filters for: Discretization, normalization, resampling, attribute

selection, transforming and combining attributes, …

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Explorer: building “classifiers” Classifiers in WEKA are models for predicting

nominal or numeric quantities

Implemented learning schemes include: Decision trees and lists, instance-based classifiers,

support vector machines, multi-layer perceptrons, logistic regression, Bayes’ nets, …

“Meta”-classifiers include: Bagging, boosting, stacking, error-correcting output

codes, locally weighted learning, …

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QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture.

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QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture.

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QuickTime™ and a TIFF (LZW) decompressor are needed to see this picture.

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Explorer: clustering data WEKA contains “clusterers” for finding groups of

similar instances in a dataset

Implemented schemes are: k-Means, EM, Cobweb, X-means, FarthestFirst

Clusters can be visualized and compared to “true” clusters (if given)

Evaluation based on loglikelihood if clustering scheme produces a probability distribution

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Explorer: finding associations WEKA contains an implementation of the Apriori

algorithm for learning association rules Works only with discrete data

Can identify statistical dependencies between groups of attributes: milk, butter bread, eggs (with confidence 0.9 and

support 2000)

Apriori can compute all rules that have a given minimum support and exceed a given confidence

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Explorer: attribute selection Panel that can be used to investigate which

(subsets of) attributes are the most predictive ones

Attribute selection methods contain two parts: A search method: best-first, forward selection,

random, exhaustive, genetic algorithm, ranking

An evaluation method: correlation-based, wrapper, information gain, chi-squared, …

Very flexible: WEKA allows (almost) arbitrary combinations of these two

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Explorer: data visualization

Visualization very useful in practice: e.g. helps to determine difficulty of the learning problem

WEKA can visualize single attributes (1-d) and pairs of attributes (2-d) To do: rotating 3-d visualizations (Xgobi-style)

Color-coded class values

“Jitter” option to deal with nominal attributes (and to detect “hidden” data points)

“Zoom-in” function

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Performing experiments Experimenter makes it easy to compare the

performance of different learning schemes

For classification and regression problems

Results can be written into file or database

Evaluation options: cross-validation, learning curve, hold-out

Can also iterate over different parameter settings

Significance-testing built in!

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The Knowledge Flow GUI New graphical user interface for WEKA

Java-Beans-based interface for setting up and running machine learning experiments

Data sources, classifiers, etc. are beans and can be connected graphically

Data “flows” through components: e.g.,

“data source” -> “filter” -> “classifier” -> “evaluator”

Layouts can be saved and loaded again later

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Conclusion: try it yourself!

WEKA is available at

http://www.cs.waikato.ac.nz/ml/weka

Also has a list of projects based on WEKA

WEKA contributors:

Abdelaziz Mahoui, Alexander K. Seewald, Ashraf M. Kibriya, Bernhard Pfahringer , Brent Martin, Peter Flach, Eibe Frank ,Gabi Schmidberger ,Ian H. Witten , J. Lindgren, Janice Boughton, Jason Wells, Len Trigg, Lucio de Souza Coelho, Malcolm Ware, Mark Hall ,Remco Bouckaert , Richard Kirkby, Shane Butler, Shane Legg, Stuart Inglis, Sylvain Roy,

Tony Voyle, Xin Xu, Yong Wang, Zhihai Wang