public Map<Integer, List<LocationBean>> clusterFromArray(
double[][] distanceArray, List<LocationBean> locations, double distance) {
Map<Integer, List<LocationBean>> groupings = new HashMap<Integer, List<LocationBean>>();
int grouping = 1;
for (LocationBean location : locations) {
location.setGroup(0);
}
for (int x = 0; x < locations.size(); x++) {
if (locations.get(x).getGroup() == 0) {
while (groupings.containsKey(grouping)) {
grouping++;
}
// System.out.println("Creating new group: " + grouping + " for point at " + x + " with name
// " + locations.get(x).getName());
locations.get(x).setGroup(grouping);
groupings.put(grouping, new ArrayList<LocationBean>());
groupings.get(grouping).add(locations.get(x));
} else {
grouping = locations.get(x).getGroup();
}
for (int y = 0; y < locations.size(); y++) {
if (y > x) { // // avoid processing the duplicate half of the array
if (distanceArray[x][y] <= distance) {
if (locations.get(y).getGroup() == 0) {
locations.get(y).setGroup(grouping);
groupings.get(grouping).add(locations.get(y));
// System.out.print(" +" + locations.get(y).getName() + " ");
} else if (locations.get(y).getGroup() == grouping) {
//// do nothing?
} else { // combine groups
int otherGroup = locations.get(y).getGroup();
// System.out.println("Combining groups " + grouping + " (" +
// groupings.get(grouping).size() + ") and " + otherGroup + "(" +
// groupings.get(otherGroup).size() + ")");
int originalSize = groupings.get(grouping).size();
for (int i = 0; i < originalSize; i++) {
// System.out.print(i + " ");
groupings.get(otherGroup).add(groupings.get(grouping).remove(0));
}
locations.get(x).setGroup(otherGroup);
}
}
}
}
// System.out.println("Group " + grouping + " has size " + groupings.get(grouping).size());
}
//// Prune empty groupings - not a necessary step, but helps clean up the result a bit.
Set<Integer> keys = groupings.keySet();
int maxKey = 0;
for (Integer key :
keys) { // since there is no gaurantee about consecutive group numbers, we have to go
// through all possible keys
if (key > maxKey) maxKey = key;
}
for (int i = 1; i <= maxKey; i++) {
if (groupings.containsKey(i) && groupings.get(i).size() == 0) {
// System.out.println("removing group " + i);
groupings.remove(i);
}
}
return groupings;
}
