/**
* Performs the hybrid relevant object discovery technique. Collects samples from around the
* clusters and then if uses the grid-structure to detect sparse grid-cells and for those it
* collects samples around the grid-center and returns ALL of the samples we collected.
*
* @param exploreTupleSize number of clusters, number of grids to explore
* @return ArrayList<Tuple> the samples that we have collected with this technique.
*/
@Override
public ArrayList<Tuple> explore(int exploreTupleSize) throws Exception {
ArrayList<Tuple> samples = new ArrayList<Tuple>(); // samples to return for labeling
// get all the samples from the clusters to present to the user
samples.addAll(clusters.explore(exploreTupleSize));
// System.out.println("Added "+samples.size()+" samples from the clusters.");
// for the grid-based method: get all the grids constructed
ArrayList<Tuple> gridSamples =
grids.explore(
exploreTupleSize); // we call this to construct the grids and get the samples from the
// grid exploration
// System.out.println(gridSamples.toString());
// System.out.println(gridSamples.size());
ArrayList<Tuple> gridCenters = grids.getCentersToExplore();
// System.out.println(gridCenters.toString());
// System.out.println(gridCenters.size());
// get the density for each of the grids (based on the grid - center)
// if it is less than threshold show to the user.
for (int i = 0; i < gridCenters.size(); i++) {
double s = findDensity(gridCenters.get(i));
// System.out.println("Density of this grid: "+s);
if (s < Global.DENSITY_THRESHOLD && s != 0) {
// System.out.println("This grid is sparse: "+gridCenters.get(i).toString()+", we are going
// to present this sample to the user: "+gridSamples.get(i));
samples.add(gridSamples.get(i));
}
}
return samples;
}
/**
* This method calculates the density of a grid cell according to this type:
* numberOfUniqueExistingTuples/numberOfUniqueCombinations (in the cell)
*
* @param theBoundary the boundaries of the specific cell we are calculating the density for
* @return the density of the cell.
* @throws SQLException
* @throws IOException
* @throws NumberFormatException
*/
private double findDensity(Tuple center) throws SQLException, NumberFormatException, IOException {
double density = 0.0;
// calculates the size of each grid
double gridLength = 100 / (double) grids.getGridNumber();
String query = "SELECT count(*) AS count_1 FROM ( SELECT ";
for (int i = 0; i < Global.attributes.size(); i++) {
if (i != Global.attributes.size() - 1) query += Global.attributes.get(i).getName() + " , ";
else query += Global.attributes.get(i).getName();
}
query += " FROM " + Global.TABLE_NAME + " WHERE ";
for (int i = 0; i < Global.attributes.size(); i++) {
query +=
Global.attributes.get(i).getName()
+ " >= "
+ getClosest(
Global.attributes.get(i).getDomain(),
gridLength / 2,
Double.parseDouble("" + center.valueAt(i)),
false)
+ " AND "
+ Global.attributes.get(i).getName()
+ " <= "
+ getClosest(
Global.attributes.get(i).getDomain(),
gridLength / 2,
Double.parseDouble("" + center.valueAt(i)),
true);
if (i < Global.attributes.size() - 1) {
query += " AND ";
}
}
query += " GROUP BY ";
for (int i = 0; i < Global.attributes.size(); i++) {
if (i != Global.attributes.size() - 1) query += Global.attributes.get(i).getName() + " , ";
else query += Global.attributes.get(i).getName();
}
query += ") AS anon_1";
// System.out.println("Query: "+query);
Connection connection = DBConnection.getConnection();
java.sql.Statement statement =
connection.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY);
java.sql.ResultSet rs = statement.executeQuery(query);
String result = "";
while (rs.next()) {
result = rs.getString(1);
}
int existing = Integer.parseInt(result);
rs.close();
statement.close();
ArrayList<Integer> uniques = new ArrayList<Integer>();
for (int i = 0; i < Global.attributes.size(); i++) {
String query1 = "SELECT count(distinct " + Global.attributes.get(i).getName();
query1 += ") FROM " + Global.TABLE_NAME + " WHERE ";
query1 +=
Global.attributes.get(i).getName()
+ " >= "
+ getClosest(
Global.attributes.get(i).getDomain(),
gridLength / 2,
Double.parseDouble("" + center.valueAt(i)),
false)
+ " AND "
+ Global.attributes.get(i).getName()
+ " <= "
+ getClosest(
Global.attributes.get(i).getDomain(),
gridLength / 2,
Double.parseDouble("" + center.valueAt(i)),
true);
java.sql.Statement statement1 =
connection.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.CONCUR_READ_ONLY);
java.sql.ResultSet rs1 = statement1.executeQuery(query1);
String result2 = "";
while (rs1.next()) {
result2 = rs1.getString(1);
}
uniques.add(Integer.parseInt(result2));
rs1.close();
statement1.close();
}
int possibleCombinations = uniques.get(0);
// System.out.println("First attr unique values in the cell: "+uniques.get(0));
// System.out.println("Second attr unique values in the cell: "+uniques.get(1));
// System.out.println("Here should be 2: "+uniques.size());
for (int i = 1; i < uniques.size(); i++) {
possibleCombinations *= uniques.get(i);
}
// System.out.println("Possible combinations: "+ possibleCombinations);
density = (double) existing / (double) possibleCombinations;
return density;
}
