One-class Classification of Text Streams with Concept Drift

Yang ZHANG, Xue LI, Maria Orlowska

DDDM 2008

The University of QueenslandAustralia

Outline Motivation Related Work Framework for One-class

Classification of Data Stream Learning Concept Drift under One-

class Scenario Experiment Result Future Work

Motivation

State-of-art data stream classification algorithm: Based on fully labeled data.

Impossible to label all data. Expensive to label data. Changing of user interests.

Difficult apply to real-life applications.

Scenario

The user feedback emails to the customer service section: finding out the feedback emails of a certain

newly launched product. Building a text data stream classification

system to retrieve all the ontopic feedbacks. Section manager behavior:

Patient enough to label only a few ontopic emails.

No patient to label offtopic emails.

One-class Classification of Text Stream

Challenge Concept drift. Small number of training data. No negative training data. Noisy data. Limited memory space.

Related work Semi-supervised classification of data

stream, cannot cope with concept drift. [Wu&Yang, ICDMW06]

Active learning for data stream classification, cannot cope with concept drift caused by sudden shift of user interests. [Fan&Huang, SDM04] [Fan&Huang, ICDM04]

[Huang&Dong, IDA07] Need multiply scan.

[Klinkenberg &Joachims, ICML00]

Related Work Static approaches for data stream

classification (fully labelled). [Street&Kim, KDD01] [Wang&Fan, KDD03]

Dynamic approaches for data stream classification (fully labelled). [Kolter&Maloof, ICDM03]

[Zhang&Jin,SIGmodRecord06] [Zhu&Wu, ICDM04]

One-class text classification. [Li&Liu, ECML05] [Liu&Dai, ICDM03] [Liu&Li,

AAAI04]

Proposed Approach

Base Classifier Selection – phenomena observed If the reader is very interested in a certain

topic today, say, sports, then, there is a high probability that he is also interested in sports tomorrow.

If the reader is interested in a topic, say, sports, and for some reason his interests change to another topic, say, politics, then after sometime, there is high probability that his interests will change back to sports again.

Base Classifier Selection - strategy

The ensemble should keep some recent base classifier.

The ensemble should keep some base classifiers which represent the reader's interests in the long run.

Experiment Result Dataset: 20NewsGroup We compare the following approaches:

Single Window (SW): The classifier is built on the current batch of data.

Full Memory (FM): The classifier is built on the current batch of data, together with positive samples dated back to batch 0.

Fixed Window (FW): The classifier is built on the samples from a fixed size of windows.

Ensemble (EN): The classifier is built by the algorithms proposed in this paper.

Experiment Scenarios 4 groups of experiments:

Experiment with concept drift caused by changing of user interests.

Experiment with heavy vs. gradual concept drift.

Experiment with concept drift caused by both changing of user interests and data distribution.

Experiment with 5 ontopic categories.

Experiment: concept drift caused by changing of user interests.

Experiment: concept drift caused by changing of user interests.

Experiment: concept drift caused by changing of user interests.

Experiment: heavy vs. gradual concept drift.

Experiment: heavy vs. gradual concept drift.

Experiment: heavy vs. gradual concept drift.

Experiment: changing of user interests & data distribution.

Very similar to the experiment result observed in the first group of experiment.

Experiment : 5 ontopic categories.

Experiment : 5 ontopic categories.

Experiment : 5 ontopic categories.

Conclusion & Future Research We firstly tackled the problem of

the one-class classification on streaming data, by ensemble based approach.

Future research Dynamic feature space One-class classification on general

data streaming.

Thank you!