DataReader.java

package cs475;

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Scanner;


public class DataReader {

	private Scanner _scanner;
	// Classification or regression?
	private boolean _classification;

	public DataReader(String filename, boolean classification) throws FileNotFoundException {
		this._scanner = new Scanner(new BufferedInputStream(new FileInputStream(filename)));
		this._classification = classification;
	}
	
	public void close() {
		this._scanner.close();
	}
	
	public List<Instance> readData() {
		ArrayList<Instance> instances = new ArrayList<Instance>();
		
		while (this._scanner.hasNextLine()) {
			String line = this._scanner.nextLine();
			if (line.trim().length() == 0)
				   continue;
			
			FeatureVector feature_vector = new FeatureVector();
		
			// Divide the line into features and label.
			String[] split_line = line.split(" ");

			String label_string = split_line[0];
			Label label = null;
			if (this._classification) {
				int int_label = Integer.parseInt(label_string);
				if (int_label != -1) {
					label = new ClassificationLabel(int_label);
				}
			} else {
				try {
					double double_label = Double.parseDouble(label_string);
					label = new RegressionLabel(double_label);
				} catch (Exception e) {
					
				}
			}
			for (int ii = 1; ii < split_line.length; ii++) {
				String item = split_line[ii];
				String name = item.split(":")[0];
				int index = Integer.parseInt(name);
				double value = Double.parseDouble(item.split(":")[1]);
				
				if (value != 0)
					feature_vector.add(index, value);
//				System.out.println(feature_vector.get(index));
			}
//		HashMap<Integer,Double> vectormap = feature_vector.getVector();
//		Iterator<Integer> ik = vectormap.keySet().iterator();
//		while (ik.hasNext()) {
//		    int key = ik.next();
//		    System.out.printf("K: %d", key);
//		    
//		    System.out.printf("V: %f", vectormap.get(key));
//		}
			Instance instance = new Instance(feature_vector, label);
			instances.add(instance);
		}		
		
		return instances;
	}
}