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我想在J48中設置-C
參數並運行三個存儲在哈希表中的特徵選擇算法。我想比較三者的表現,如精確度,真正積極,真正消極,F1等。但是,當我運行所有功能選擇算法時,它們會返回相同的輸出....我做錯了什麼?使用Weka進行參數優化和屬性選擇
Hashtable<String, ASEvaluation> search=new Hashtable<String, ASEvaluation>();
Instances training_data = new Instances(new BufferedReader(
new FileReader("test.arff")));
training_data.setClassIndex(training_data.numAttributes() - 1);
topAttributes = new int[training_data.numAttributes()];
AttributeSelectedClassifier classifier = new AttributeSelectedClassifier();
AttributeSelection attsel = new AttributeSelection();
search.put("Infogain", new InfoGainAttributeEval());
search.put("SymmetricalUncertAttribute",new SymmetricalUncertAttributeEval());
search.put("Chisquared",new ChiSquaredAttributeEval());
for(String key : search.keySet()) {
try{
Ranker attribute_search = new Ranker();
J48 base = new J48();
CVParameterSelection ps = new CVParameterSelection();
ps.setClassifier(base);
ps.setNumFolds(5);
ps.addCVParameter("C 0.1 0.5 5");
ps.buildClassifier(training_data);
System.out.println("---------------- " + search.get(key).toString() + " ----------------");
classifier.setClassifier(ps);
classifier.setEvaluator(search.get(key));
classifier.setSearch(attribute_search);
attsel.setEvaluator(search.get(key));
attsel.setSearch(attribute_search);
attsel.setInputFormat(training_data);
Evaluation evaluation = new Evaluation(training_data);
evaluation.crossValidateModel(ps, training_data, 10, new Random(1));
System.out.println("\nevaluation ->");
System.out.println(evaluation.toSummaryString());
System.out.println("MAE: " + evaluation.meanAbsoluteError());
} catch(Exception e) {
e.printStackTrace();
}
}
您是否檢查過功能選擇算法是否對您的數據集產生影響?他們可能真的會返回所有相同的功能集。即使他們不這樣做,'J48'也可以簡單地選擇在生成的樹中使用的屬性的相同子集。 – 2013-03-02 15:52:18