[refactor] Reduce complexity by refactoring

- Extracted csv related operations
- Divided in smaller functions
- Externalized classes

src/main/java/fr/u_paris/gla/project/idfm/CSVStreamProvider.java

@@ -0,0 +1,168 @@
+/**
+ * 
+ */
+package fr.u_paris.gla.project.idfm;
+
+import java.text.MessageFormat;
+import java.text.NumberFormat;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Locale;
+import java.util.Map;
+import java.util.Set;
+
+import fr.u_paris.gla.project.io.NetworkFormat;
+import fr.u_paris.gla.project.utils.GPS;
+
+public final class CSVStreamProvider {
+    private static final NumberFormat GPS_FORMATTER            = NetworkFormat
+            .getGPSFormatter();
+    private static final NumberFormat MINUTES_SECOND_FORMATTER = NumberFormat
+            .getInstance(Locale.ENGLISH);
+    static {
+        MINUTES_SECOND_FORMATTER.setMinimumIntegerDigits(2);
+    }
+    /** Number of seconds in a minute. */
+    private static final int  SECONDS_IN_MINUTES = 60;
+    private static final long SECONDS_IN_HOURS   = 3_600;
+    // Magically chosen values
+    /** Maximal speed in km/h */
+    private static final double MAX_SPEED             = 5;
+    /** Distance to reach maximal speed in km */
+    private static final double TWO_ACCELERATION_DISTANCE = 0.2;
+
+    private String[] line = new String[NetworkFormat.NUMBER_COLUMNS];
+
+    private Iterator<TraceEntry>      currentTrace;
+    private Iterator<List<StopEntry>> currentPath         = Collections.emptyIterator();
+    private Iterator<StopEntry>       currentSegmentStart = Collections.emptyIterator();
+    private Iterator<StopEntry>       currentSegmentEnd   = Collections.emptyIterator();
+    Map<StopEntry, Set<StopEntry>>    lineSegments        = new HashMap<>();
+
+    private StopEntry start = null;
+    private StopEntry end   = null;
+
+    private boolean hasNext = false;
+    private boolean onNext  = false;
+
+    /** Create the stream provider */
+    public CSVStreamProvider(Iterator<TraceEntry> traces) {
+        this.currentTrace = traces;
+    }
+
+    public boolean hasNext() {
+        if (!this.onNext) {
+            skipToNext();
+        }
+        return this.hasNext;
+    }
+
+    private void skipToNext() {
+        if (this.onNext) {
+            return;
+        }
+        while (!this.onNext) {
+            if (!this.currentSegmentEnd.hasNext()) {
+                skipToNextCandidatePath();
+            }
+            if (this.onNext) {
+                return;
+            }
+            skipToNextNewSegment();
+        }
+    }
+
+    private void skipToNextNewSegment() {
+        do {
+            this.start = this.currentSegmentStart.next();
+            this.lineSegments.putIfAbsent(this.start, new HashSet<>());
+            this.end = this.currentSegmentEnd.next();
+        } while (this.lineSegments.get(this.start).contains(this.end)
+                && this.currentSegmentEnd.hasNext());
+        if (!this.lineSegments.get(this.start).contains(this.end)) {
+            this.lineSegments.get(this.start).add(this.end);
+            this.onNext = true;
+            this.hasNext = true;
+        }
+    }
+
+    /** Move the reading head of path to the next one that has at least two
+     * elements */
+    private void skipToNextCandidatePath() {
+        currentSegmentStart = null;
+        do {
+            while (!this.currentPath.hasNext()) {
+                if (!this.currentTrace.hasNext()) {
+                    this.hasNext = false;
+                    this.onNext = true;
+                    return;
+                }
+                TraceEntry trace = this.currentTrace.next();
+                this.currentPath = trace.getPaths().iterator();
+                this.line[NetworkFormat.LINE_INDEX] = trace.lname;
+                this.lineSegments.clear();
+            }
+            List<StopEntry> path = this.currentPath.next();
+            this.currentSegmentEnd = path.iterator();
+            if (this.currentSegmentEnd.hasNext()) {
+                this.currentSegmentEnd.next();
+                this.currentSegmentStart = path.iterator();
+            }
+        } while (currentSegmentStart == null);
+    }
+
+    public String[] next() {
+        if (!this.onNext) {
+            skipToNext();
+        }
+        this.onNext = false;
+
+        fillStation(this.start, this.line, NetworkFormat.START_INDEX);
+        fillStation(this.end, this.line, NetworkFormat.STOP_INDEX);
+        double distance = GPS.distance(this.start.latitude, this.start.longitude,
+                this.end.latitude, this.end.longitude);
+        this.line[NetworkFormat.DISTANCE_INDEX] = NumberFormat.getInstance(Locale.ENGLISH)
+                .format(distance);
+        this.line[NetworkFormat.DURATION_INDEX] = formatTime(
+                (long) Math.ceil(distanceToTime(distance) * SECONDS_IN_HOURS));
+        this.line[NetworkFormat.VARIANT_INDEX] = Integer
+                .toString(this.lineSegments.get(this.start).size() - 1);
+
+        return Arrays.copyOf(this.line, this.line.length);
+    }
+
+    /** @param stop1
+     * @param nextLine
+     * @param i */
+    private static void fillStation(StopEntry stop, String[] nextLine, int index) {
+        nextLine[index] = stop.lname;
+        nextLine[index + 1] = MessageFormat.format("{0}, {1}", //$NON-NLS-1$
+                GPS_FORMATTER.format(stop.latitude),
+                GPS_FORMATTER.format(stop.longitude));
+
+    }
+
+    /** @param distanceToTime
+     * @return */
+    private static String formatTime(long time) {
+        return MessageFormat.format("{0}:{1}", //$NON-NLS-1$
+                MINUTES_SECOND_FORMATTER.format(time / SECONDS_IN_MINUTES), MINUTES_SECOND_FORMATTER.format(time % SECONDS_IN_MINUTES));
+    }
+
+    /** A tool method to give a delay to go through a certain distance.
+     * <p>
+     * This is a model with an linear acceleration and deceleration periods and a
+     * constant speed in between.
+     * 
+     * @param distance the distance (in km)
+     * @return the duration of the trip (in hours) */
+    private static double distanceToTime(double distance) {
+        return Math.max(0, distance - TWO_ACCELERATION_DISTANCE) / MAX_SPEED
+                + Math.pow(Math.min(distance, TWO_ACCELERATION_DISTANCE) / MAX_SPEED, 2);
+    }
+
+}

src/main/java/fr/u_paris/gla/project/idfm/IDFMNetworkExtractor.java

@@ -3,51 +3,31 @@
  */
 package fr.u_paris.gla.project.idfm;
 
-import java.io.BufferedReader;
-import java.io.FileWriter;
 import java.io.IOException;
-import java.io.InputStream;
-import java.io.InputStreamReader;
-import java.io.Reader;
-import java.net.URL;
-import java.nio.charset.StandardCharsets;
-import java.text.Format;
 import java.text.MessageFormat;
-import java.text.NumberFormat;
 import java.util.ArrayList;
-import java.util.Collections;
-import java.util.Comparator;
 import java.util.HashMap;
 import java.util.HashSet;
 import java.util.List;
-import java.util.Locale;
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Set;
-import java.util.function.BiFunction;
-import java.util.function.Consumer;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import java.util.stream.Stream;
 
 import org.json.JSONArray;
 import org.json.JSONException;
 import org.json.JSONObject;
 
-import com.opencsv.CSVParserBuilder;
-import com.opencsv.CSVReader;
-import com.opencsv.CSVReaderBuilder;
-import com.opencsv.CSVWriterBuilder;
-import com.opencsv.ICSVParser;
-import com.opencsv.ICSVWriter;
-import com.opencsv.exceptions.CsvValidationException;
-
-import fr.u_paris.gla.project.io.NetworkFormat;
+import fr.u_paris.gla.project.utils.CSVTools;
 import fr.u_paris.gla.project.utils.GPS;
 
 /** Code of an extractor for the data from IDF mobilite.
  * 
  * @author Emmanuel Bigeon */
 public class IDFMNetworkExtractor {
+
     /** The logger for information on the process */
     private static final Logger LOGGER = Logger
             .getLogger(IDFMNetworkExtractor.class.getName());
@@ -68,83 +48,10 @@ public class IDFMNetworkExtractor {
 
     // Magically chosen values
     /** A number of stops on each line */
-    private static final int    GUESS_STOPS_BY_LINE   = 5;
-    /** Maximal speed in km/h */
-    private static final double MAX_SPEED             = 5;
-    /** Distance to reach maximal speed in km */
-    private static final double ACCELERATION_DISTANCE = 0.1;
+    private static final int GUESS_STOPS_BY_LINE = 5;
 
     // Well named constants
-    private static final double _250_METERS      = .25;
-    private static final long   SECONDS_IN_HOURS = 3_600;
-
-    private static final Format GPS_FORMATTER = NetworkFormat.getGPSFormatter();
-
-    public static class StopEntry {
-        private String      lname;
-        public final double longitude;
-        public final double latitude;
-
-        /** Create the stop
-         * 
-         * @param lname
-         * @param longitude
-         * @param latitude */
-        public StopEntry(String lname, double longitude, double latitude) {
-            super();
-            this.lname = lname;
-            this.longitude = longitude;
-            this.latitude = latitude;
-        }
-
-        @Override
-        public String toString() {
-            return MessageFormat.format("{0} [{1}, {2}]", this.lname, this.longitude,
-                    this.latitude);
-        }
-    }
-
-    public static final class UnidentifiedStopEntry extends StopEntry {
-        /** Create the stop
-         * 
-         * @param longitude
-         * @param latitude */
-        public UnidentifiedStopEntry(double longitude, double latitude) {
-            super("Unidentified", longitude, latitude);
-        }
-
-        List<StopEntry> candidates = new ArrayList<>();
-
-        @Override
-        public String toString() {
-            return "UnidentifiedStop [candidates=" + this.candidates + "]";
-        }
-    }
-
-    private static final class TraceEntry {
-        String                lname;
-        List<List<StopEntry>> stops = new ArrayList<>();
-    }
-
-    public static void readCSVFromURL(String url, Consumer<String[]> contentLineConsumer)
-            throws IOException {
-        ICSVParser parser = new CSVParserBuilder().withSeparator(';').build();
-        try (InputStream is = new URL(url).openStream();
-                Reader reader = new BufferedReader(
-                        new InputStreamReader(is, StandardCharsets.UTF_8))) {
-            CSVReaderBuilder csvBuilder = new CSVReaderBuilder(reader)
-                    .withCSVParser(parser);
-            try (CSVReader csv = csvBuilder.build()) {
-                String[] line = csv.readNextSilently(); // Eliminate header
-                while (csv.peek() != null) {
-                    line = csv.readNext();
-                    contentLineConsumer.accept(line);
-                }
-            }
-        } catch (CsvValidationException e) {
-            throw new IOException("Invalid csv file for lines", e);
-        }
-    }
+    private static final double QUARTER_KILOMETER = .25;
 
     /** Main entry point for the extractor of IDF mobilite data into a network as
      * defined by this application.
@@ -159,165 +66,103 @@ public class IDFMNetworkExtractor {
 
         Map<String, TraceEntry> traces = new HashMap<>();
         try {
-            readCSVFromURL(TRACE_FILE_URL, (String[] line) -> {
-                TraceEntry entry = new TraceEntry();
-                entry.lname = line[IDFM_TRACE_SNAME_INDEX];
-                List<List<StopEntry>> buildPaths = buildPaths(
-                        line[IDFM_TRACE_SHAPE_INDEX]);
-                entry.stops.addAll(buildPaths);
-                if (buildPaths.isEmpty()) {
-                    LOGGER.severe(() -> MessageFormat.format(
-                            "Line {0} has no provided itinerary and was ignored",
-                            entry.lname));
-                } else {
-                    traces.put(line[IDFM_TRACE_ID_INDEX], entry);
-                }
-            });
+            CSVTools.readCSVFromURL(TRACE_FILE_URL,
+                    (String[] line) -> addLine(line, traces));
         } catch (IOException e) {
             LOGGER.log(Level.SEVERE, "Error while reading the line paths", e);
         }
 
         List<StopEntry> stops = new ArrayList<>(traces.size() * GUESS_STOPS_BY_LINE);
         try {
-            readCSVFromURL(STOPS_FILE_URL, (String[] line) -> {
-                StopEntry entry = new StopEntry(line[IDFM_STOPS_NAME_INDEX],
-                        Double.parseDouble(line[IDFM_STOPS_LON_INDEX]),
-                        Double.parseDouble(line[IDFM_STOPS_LAT_INDEX]));
-                String rid = line[IDFM_STOPS_RID_INDEX];
-                BiFunction<? super String, ? super TraceEntry, ? extends TraceEntry> func = (
-                        k, trace) -> {
-                    for (List<StopEntry> path : trace.stops) {
-                        for (StopEntry stopEntry : path) {
-                            if (stopEntry instanceof UnidentifiedStopEntry
-                                    && GPS.distance(entry.latitude, entry.longitude,
-                                            stopEntry.latitude,
-                                            stopEntry.longitude) < _250_METERS) {
-                                ((UnidentifiedStopEntry) stopEntry).candidates.add(entry);
-                            }
-                        }
-                    }
-                    return trace;
-                };
-                traces.computeIfPresent(rid, func);
-                stops.add(entry);
-            });
+            CSVTools.readCSVFromURL(STOPS_FILE_URL,
+                    (String[] line) -> addStop(line, traces, stops));
         } catch (IOException e) {
             LOGGER.log(Level.SEVERE, "Error while reading the stops", e);
         }
 
+        cleanTraces(traces);
+
+        CSVStreamProvider provider = new CSVStreamProvider(traces.values().iterator());
+
+        try {
+            CSVTools.writeCSVToFile(args[0], Stream.iterate(provider.next(),
+                    t -> provider.hasNext(), t -> provider.next()));
+        } catch (IOException e) {
+            LOGGER.log(Level.SEVERE, e,
+                    () -> MessageFormat.format("Could not write in file {0}", args[0]));
+        }
+    }
+
+    private static void cleanTraces(Map<String, TraceEntry> traces) {
         Set<String> toRemove = new HashSet<>();
         for (Entry<String, TraceEntry> traceEntry : traces.entrySet()) {
             TraceEntry trace = traceEntry.getValue();
-            for (List<StopEntry> path : trace.stops) {
-                for (int i = 0; i < path.size(); i++) {
-                    StopEntry stop = path.get(i);
-                    if (stop instanceof UnidentifiedStopEntry)
-                        stop = resolve((UnidentifiedStopEntry) stop);
-                    if (stop instanceof UnidentifiedStopEntry
-                            && ((UnidentifiedStopEntry) stop).candidates.isEmpty()) {
-                        LOGGER.severe("Missing stop for line " + trace.lname
-                                + ". Line will be removed");
-                        toRemove.add(traceEntry.getKey());
-                        continue;
-                    }
-                    path.set(i, stop);
-                }
+            if (!cleanLine(trace.getPaths())) {
+                LOGGER.severe(() -> MessageFormat.format(
+                        "Missing stop for line {0}. Line will be removed", trace.lname));
+                toRemove.add(traceEntry.getKey());
             }
         }
 
         for (String string : toRemove) {
             traces.remove(string);
         }
+    }
 
-        // Export content in required format
-        try (FileWriter writer = new FileWriter(args[0], StandardCharsets.UTF_8)) {
-            CSVWriterBuilder wBuilder = new CSVWriterBuilder(writer).withSeparator(';');
-            try (ICSVWriter csv = wBuilder.build()) {
-                for (Entry<String, TraceEntry> traceEntry : traces.entrySet()) {
-                    Map<StopEntry, Set<StopEntry>> lineSegments = new HashMap<>();
-                    String[] nextLine = new String[NetworkFormat.NUMBER_COLUMNS];
-                    nextLine[NetworkFormat.LINE_INDEX] = traceEntry.getValue().lname;
-                    for (List<StopEntry> path : traceEntry.getValue().stops) {
-                        for (int i = 0; i < path.size() - 1; i++) {
-                            StopEntry stop1 = path.get(i);
-                            lineSegments.putIfAbsent(stop1, new HashSet<>());
-                            StopEntry stop2 = path.get(i + 1);
-                            if (!lineSegments.get(stop1).contains(stop2)) {
-                                fillStation(stop1, nextLine, NetworkFormat.START_INDEX);
-                                fillStation(stop2, nextLine, NetworkFormat.STOP_INDEX);
-                                double distance = GPS.distance(stop1.latitude,
-                                        stop1.longitude, stop2.latitude, stop2.longitude);
-                                nextLine[NetworkFormat.DISTANCE_INDEX] = NumberFormat
-                                        .getInstance(Locale.ENGLISH).format(distance);
-                                nextLine[NetworkFormat.DURATION_INDEX] = formatTime(
-                                        (long) Math.ceil(distanceToTime(distance)
-                                                * SECONDS_IN_HOURS));
-                                nextLine[NetworkFormat.VARIANT_INDEX] = Integer
-                                        .toString(lineSegments.get(stop1).size());
-                                csv.writeNext(nextLine);
-                                lineSegments.get(stop1).add(stop2);
-                            }
-                        }
-                    }
+    /** @param path */
+    private static boolean cleanLine(List<List<StopEntry>> stops) {
+        for (List<StopEntry> path : stops) {
+            for (int i = 0; i < path.size(); i++) {
+                StopEntry stop = path.get(i);
+                if (!(stop instanceof UnidentifiedStopEntry)) {
+                    continue;
+                }
+                UnidentifiedStopEntry unidentified = (UnidentifiedStopEntry) stop;
+                StopEntry stopResolution = unidentified.resolve();
+                if (stopResolution == null) {
+                    return false;
+                }
+                path.set(i, stopResolution);
+            }
+        }
+        return true;
+    }
 
+    private static void addStop(String[] line, Map<String, TraceEntry> traces,
+            List<StopEntry> stops) {
+        StopEntry entry = new StopEntry(line[IDFM_STOPS_NAME_INDEX],
+                Double.parseDouble(line[IDFM_STOPS_LON_INDEX]),
+                Double.parseDouble(line[IDFM_STOPS_LAT_INDEX]));
+        String rid = line[IDFM_STOPS_RID_INDEX];
+        traces.computeIfPresent(rid,
+                (String k, TraceEntry trace) -> addCandidate(trace, entry));
+        stops.add(entry);
+    }
+
+    private static void addLine(String[] line, Map<String, TraceEntry> traces) {
+        TraceEntry entry = new TraceEntry(line[IDFM_TRACE_SNAME_INDEX]);
+        List<List<StopEntry>> buildPaths = buildPaths(line[IDFM_TRACE_SHAPE_INDEX]);
+        entry.getPaths().addAll(buildPaths);
+        if (buildPaths.isEmpty()) {
+            LOGGER.severe(() -> MessageFormat.format(
+                    "Line {0} has no provided itinerary and was ignored", entry.lname));
+        } else {
+            traces.put(line[IDFM_TRACE_ID_INDEX], entry);
+        }
+    }
+
+    private static TraceEntry addCandidate(TraceEntry trace, StopEntry entry) {
+        for (List<StopEntry> path : trace.getPaths()) {
+            for (StopEntry stopEntry : path) {
+                if (stopEntry instanceof UnidentifiedStopEntry unidentified
+                        && GPS.distance(entry.latitude, entry.longitude,
+                                stopEntry.latitude,
+                                stopEntry.longitude) < QUARTER_KILOMETER) {
+                    unidentified.addCandidate(entry);
                 }
             }
-        } catch (IOException e) {
-            LOGGER.log(Level.SEVERE, e, () -> "Could not write in file " + args[1]);
         }
-    }
-
-    /** @param distanceToTime
-     * @return */
-    private static String formatTime(long time) {
-        NumberFormat format = NumberFormat.getInstance(Locale.ENGLISH);
-        format.setMinimumIntegerDigits(2);
-        return MessageFormat.format("{0}:{1}", format.format(time / 60),
-                format.format(time % 60));
-    }
-
-    /** A tool method to give a delay to go through a certain distance.
-     * <p>
-     * This is a model with an linear acceleration and deceleration periods and a
-     * constant speed in between.
-     * 
-     * @param distance the distance (in km)
-     * @return the duration of the trip (in hours) */
-    private static double distanceToTime(double distance) {
-        return Math.max(0, distance - 2 * ACCELERATION_DISTANCE) / MAX_SPEED
-                + Math.pow(Math.min(distance, 2 * ACCELERATION_DISTANCE) / MAX_SPEED, 2);
-    }
-
-    /** @param stop1
-     * @param nextLine
-     * @param i */
-    private static void fillStation(StopEntry stop, String[] nextLine, int index) {
-        nextLine[index] = stop.lname;
-        nextLine[index + 1] = MessageFormat.format("{0}, {1}",
-                GPS_FORMATTER.format(stop.latitude),
-                GPS_FORMATTER.format(stop.longitude));
-
-    }
-
-    /** @param stop
-     * @return */
-    private static StopEntry resolve(UnidentifiedStopEntry stop) {
-
-        if (stop.candidates.isEmpty()) {
-            LOGGER.severe("Unable to find stop name, will use a placeholder");
-            return stop;
-        }
-        if (stop.candidates.size() == 1) {
-            return stop.candidates.get(0);
-        }
-        Collections.sort(stop.candidates,
-                (Comparator<? super StopEntry>) (StopEntry s1,
-                        StopEntry s2) -> (int) Math.signum((GPS.distance(stop.latitude,
-                                stop.longitude, s1.latitude, s1.longitude)
-                                - GPS.distance(stop.latitude, stop.longitude, s2.latitude,
-                                        s2.longitude))));
-
-        return stop.candidates.get(0);
+        return trace;
     }
 
     private static List<List<StopEntry>> buildPaths(String pathsJSON) {
@@ -341,7 +186,8 @@ public class IDFMNetworkExtractor {
             }
         } catch (JSONException e) {
             // Ignoring invalid element!
-            LOGGER.log(Level.FINE, "Invalid json element " + pathsJSON, e); //$NON-NLS-1$
+            LOGGER.log(Level.FINE, e,
+                    () -> MessageFormat.format("Invalid json element {0}", pathsJSON)); //$NON-NLS-1$
         }
         return all;
     }

src/main/java/fr/u_paris/gla/project/idfm/StopEntry.java

@@ -0,0 +1,71 @@
+/**
+ * 
+ */
+package fr.u_paris.gla.project.idfm;
+
+import java.text.MessageFormat;
+import java.util.Objects;
+
+/** A transport stop data.
+ * 
+ * @author Emmanuel Bigeon */
+public class StopEntry implements Comparable<StopEntry> {
+    public final String lname;
+    public final double longitude;
+    public final double latitude;
+
+    /** Create the stop
+     * 
+     * @param lname
+     * @param longitude
+     * @param latitude */
+    public StopEntry(String lname, double longitude, double latitude) {
+        super();
+        this.lname = lname;
+        this.longitude = longitude;
+        this.latitude = latitude;
+    }
+
+    @Override
+    public String toString() {
+        return MessageFormat.format("{0} [{1}, {2}]", this.lname, this.longitude, //$NON-NLS-1$
+                this.latitude);
+    }
+
+    @Override
+    public int compareTo(StopEntry o) {
+        if (latitude < o.latitude) {
+            return -1;
+        }
+        if (latitude > o.latitude) {
+            return 1;
+        }
+        if (longitude < o.longitude) {
+            return -1;
+        }
+        if (longitude > o.longitude) {
+            return 1;
+        }
+        return lname.compareTo(o.lname);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(latitude, lname, longitude);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (obj == null)
+            return false;
+        if (getClass() != obj.getClass())
+            return false;
+        StopEntry other = (StopEntry) obj;
+        return Double.doubleToLongBits(latitude) == Double
+                .doubleToLongBits(other.latitude) && Objects.equals(lname, other.lname)
+                && Double.doubleToLongBits(longitude) == Double
+                        .doubleToLongBits(other.longitude);
+    }
+}

src/main/java/fr/u_paris/gla/project/idfm/TraceEntry.java

@@ -0,0 +1,34 @@
+/**
+ * 
+ */
+package fr.u_paris.gla.project.idfm;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+/** Representation of a transport line
+ * 
+ * @author Emmanuel Bigeon */
+public final class TraceEntry {
+    public final String           lname;
+    private List<List<StopEntry>> paths = new ArrayList<>();
+
+    /** Create a transport line.
+     * 
+     * @param lname the name of the line */
+    public TraceEntry(String lname) {
+        super();
+        this.lname = lname;
+    }
+
+    // FIXME list of lists are bad practice in direct access...
+    /** @return the list of paths */
+    public List<List<StopEntry>> getPaths() {
+        return Collections.unmodifiableList(paths);
+    }
+
+    public void addPath(List<StopEntry> path) {
+        paths.add(new ArrayList<>(path));
+    }
+}

src/main/java/fr/u_paris/gla/project/idfm/UnidentifiedStopEntry.java

@@ -0,0 +1,72 @@
+/**
+ * 
+ */
+package fr.u_paris.gla.project.idfm;
+
+import java.text.MessageFormat;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.List;
+import java.util.Objects;
+
+import fr.u_paris.gla.project.utils.GPS;
+
+/** A transport stop with unidentified name and potential candidates as to their
+ * real value.
+ * 
+ * @author Emmanuel Bigeon */
+public final class UnidentifiedStopEntry extends StopEntry {
+    private List<StopEntry> candidates = new ArrayList<>();
+
+    /** Create the stop
+     * 
+     * @param longitude
+     * @param latitude */
+    public UnidentifiedStopEntry(double longitude, double latitude) {
+        super("Unidentified", longitude, latitude); //$NON-NLS-1$
+    }
+
+    @Override
+    public String toString() {
+        return MessageFormat.format("UnidentifiedStop [candidates={0}]", this.candidates); //$NON-NLS-1$
+    }
+
+    /** Get the most likely choice for the stop
+     * 
+     * @return the most likely candidate */
+    public StopEntry resolve() {
+        if (candidates.isEmpty()) {
+            return null;
+        }
+        if (candidates.size() == 1) {
+            return candidates.get(0);
+        }
+        Collections.sort(candidates, (Comparator<? super StopEntry>) (StopEntry s1,
+                StopEntry s2) -> (int) Math.signum((GPS.distance(latitude, longitude,
+                        s1.latitude, s1.longitude)
+                        - GPS.distance(latitude, longitude, s2.latitude, s2.longitude))));
+
+        return candidates.get(0);
+    }
+
+    /** Add a candidate.
+     * 
+     * @param entry the candidate */
+    public void addCandidate(StopEntry entry) {
+        candidates.add(entry);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj)
+            return true;
+        if (!super.equals(obj))
+            return false;
+        if (getClass() != obj.getClass())
+            return false;
+        UnidentifiedStopEntry other = (UnidentifiedStopEntry) obj;
+        return Objects.equals(candidates, other.candidates);
+    }
+
+}

src/main/java/fr/u_paris/gla/project/utils/CSVTools.java

@@ -0,0 +1,65 @@
+/**
+ * 
+ */
+package fr.u_paris.gla.project.utils;
+
+import java.io.BufferedReader;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.InputStreamReader;
+import java.io.Reader;
+import java.net.URL;
+import java.nio.charset.StandardCharsets;
+import java.util.function.Consumer;
+import java.util.stream.Stream;
+
+import com.opencsv.CSVParserBuilder;
+import com.opencsv.CSVReader;
+import com.opencsv.CSVReaderBuilder;
+import com.opencsv.CSVWriterBuilder;
+import com.opencsv.ICSVParser;
+import com.opencsv.ICSVWriter;
+import com.opencsv.exceptions.CsvValidationException;
+
+/** A CSV tool class.
+ * 
+ * @author Emmanuel Bigeon */
+public final class CSVTools {
+
+    /** Hidden constructor of tool class */
+    private CSVTools() {
+        // Tool class
+    }
+
+    public static void readCSVFromURL(String url, Consumer<String[]> contentLineConsumer)
+            throws IOException {
+        ICSVParser parser = new CSVParserBuilder().withSeparator(';').build();
+        try (InputStream is = new URL(url).openStream();
+                Reader reader = new BufferedReader(
+                        new InputStreamReader(is, StandardCharsets.UTF_8))) {
+            CSVReaderBuilder csvBuilder = new CSVReaderBuilder(reader)
+                    .withCSVParser(parser);
+            try (CSVReader csv = csvBuilder.build()) {
+                String[] line = csv.readNextSilently(); // Eliminate header
+                while (csv.peek() != null) {
+                    line = csv.readNext();
+                    contentLineConsumer.accept(line);
+                }
+            }
+        } catch (CsvValidationException e) {
+            throw new IOException("Invalid csv file", e); //$NON-NLS-1$
+        }
+    }
+
+    public static void writeCSVToFile(String filename,
+            Stream<String[]> contentLineConsumer) throws IOException {
+        try (FileWriter writer = new FileWriter(filename, StandardCharsets.UTF_8)) {
+            CSVWriterBuilder wBuilder = new CSVWriterBuilder(writer).withSeparator(';');
+            try (ICSVWriter csv = wBuilder.build()) {
+                contentLineConsumer.forEachOrdered(csv::writeNext);
+            }
+        }
+    }
+
+}