MovielensProcessor.java

package file.preprocessing;

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.sql.Timestamp;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

public class MovielensProcessor {

	public static boolean processFile(String inputFile, String outputFile, String ratingFile) {
		try {
			Map<String, String> ratingMap = null;
			if (ratingFile != null) {
				ratingMap = new LinkedHashMap<String, String>();
				FileReader reader = new FileReader(new File("./data/csv/ml_core/" + ratingFile));
				BufferedReader br = new BufferedReader(reader);
				String line = null;
				while ((line = br.readLine()) != null) {
					String[] lineParts = line.split("::");
					ratingMap.put(lineParts[0] + "_" + lineParts[1], lineParts[2]);
				}
				br.close();
			}
			
			
			FileReader reader = new FileReader(new File("./data/csv/ml_core/" + inputFile));
			FileWriter writer = new FileWriter(new File("./data/csv/ml_core/" + outputFile + ".txt"));
			BufferedReader br = new BufferedReader(reader);
			BufferedWriter bw = new BufferedWriter(writer);
			String line = null;
			String resID = "", userHash = "", timestamp = "";
			List<String> tags = new ArrayList<String>();
			
			while ((line = br.readLine()) != null) {
				String[] lineParts = line.split("::");
				String tag = lineParts[2];
				//if (!filter || (!tag.contains("no-tag") && !tag.contains("-import"))) {
					if (!resID.isEmpty() && !userHash.isEmpty() && (!resID.equals(lineParts[1]) || !userHash.equals(lineParts[0]))) {
						writeLine(bw, resID, userHash, timestamp, tags, ratingMap);
						tags.clear();
					}
					resID = lineParts[1];
					userHash = lineParts[0];
					timestamp = lineParts[3];
					tags.add(tag);
				//}
			}
			writeLine(bw, resID, userHash, timestamp, tags, ratingMap);
			
			br.close();
			bw.flush();
			bw.close();
			return true;
		} catch (Exception e) {
			e.printStackTrace();
		}
		return false;
	}
	
	private static boolean writeLine(BufferedWriter bw, String resID, String userHash, String timestamp, List<String> tags, Map<String, String> ratingMap) {
		try {
			String tagString = "";
			for (String tag : tags) {
				tagString += (tag + ",");
			}
			tagString = tagString.length() > 0 ? tagString.substring(0, tagString.length() - 1) : "";
			
			String rating = ";\"\"";
			boolean isRated = false;
			if(ratingMap != null) {
				rating = ratingMap.get(userHash + "_" + resID);
				if (rating != null) {
					double ratingVal = Double.parseDouble(rating) * 2.0;
					rating = ";\"" + (int)ratingVal + "\"";
					isRated = true;
				} else {
					rating = ";\"\"";
				}
			}
			
			if (isRated) {
				bw.write("\"" + userHash + "\";\"" + resID + "\";\"" + timestamp + "\";\"" + tagString + "\";\"\"" + rating + "\n");
			}
			return true;
		} catch (IOException e) {
			e.printStackTrace();
		}
		return false;
	}
}