Skip to content

Commit

Permalink
Added implementation of QuadraticPickSeeds; QuadraticPickNext
Browse files Browse the repository at this point in the history
  • Loading branch information
Russ Weeks committed Aug 28, 2012
1 parent 34e9ce0 commit 25ebc2e
Show file tree
Hide file tree
Showing 2 changed files with 128 additions and 46 deletions.
164 changes: 123 additions & 41 deletions src/com/newbrightidea/util/RTree.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -21,13 +21,16 @@
*/
public class RTree<T>
{
public enum SeedPicker { LINEAR, QUADRATIC }

private final int maxEntries;
private final int minEntries;
private final int numDims;

private final float[] pointDims;

private final SeedPicker seedPicker;

private Node root;

private volatile int size;
Expand All @@ -42,16 +45,22 @@ public class RTree<T>
* @param numDims
* the number of dimensions of the RTree.
*/
public RTree(int maxEntries, int minEntries, int numDims)
public RTree(int maxEntries, int minEntries, int numDims, SeedPicker seedPicker)
{
assert (minEntries <= (maxEntries / 2));
this.numDims = numDims;
this.maxEntries = maxEntries;
this.minEntries = minEntries;
this.seedPicker = seedPicker;
pointDims = new float[numDims];
root = buildRoot(true);
}

public RTree(int maxEntries, int minEntries, int numDims)
{
this(maxEntries, minEntries, numDims, SeedPicker.LINEAR);
}

private Node buildRoot(boolean asLeaf)
{
float[] initCoords = new float[numDims];
Expand All @@ -70,7 +79,7 @@ private Node buildRoot(boolean asLeaf)
*/
public RTree()
{
this(50, 2, 2);
this(50, 2, 2, SeedPicker.LINEAR);
}

/**
Expand Down Expand Up @@ -375,6 +384,10 @@ private void adjustTree(Node n, Node nn)

private Node[] splitNode(Node n)
{
// TODO: this class probably calls "tighten" a little too often.
// For instance the call at the end of the "while (!cc.isEmpty())" loop
// could be modified and inlined because it's only adjusting for the addition
// of a single node. Left as-is for now for readability.
@SuppressWarnings("unchecked")
Node[] nn = new RTree.Node[]
{ n, new Node(n.coords, n.dimensions, n.leaf) };
Expand All @@ -385,32 +398,30 @@ private Node[] splitNode(Node n)
}
LinkedList<Node> cc = new LinkedList<Node>(n.children);
n.children.clear();
Node[] ss = pickSeeds(cc);
Node[] ss = seedPicker == SeedPicker.LINEAR ? lPickSeeds(cc) : qPickSeeds(cc);
nn[0].children.add(ss[0]);
nn[1].children.add(ss[1]);
tighten(nn);
while (!cc.isEmpty())
{
if ((nn[0].children.size() >= minEntries)
&& (nn[1].children.size() + cc.size() == minEntries))
{
nn[1].children.addAll(cc);
cc.clear();
tighten(nn[0]); // Not sure this is required.
tighten(nn[1]);
tighten(nn); // Not sure this is required.
return nn;
}
else if ((nn[1].children.size() >= minEntries)
&& (nn[0].children.size() + cc.size() == minEntries))
{
nn[0].children.addAll(cc);
cc.clear();
tighten(nn[0]); // Not sure this is required.
tighten(nn[1]);
tighten(nn); // Not sure this is required.
return nn;
}
Node c = cc.pop();
Node c = seedPicker == SeedPicker.LINEAR ? lPickNext(cc) : qPickNext(cc, nn);
Node preferred;
// Implementation of linear PickNext
float e0 = getRequiredExpansion(nn[0].coords, nn[0].dimensions, c);
float e1 = getRequiredExpansion(nn[1].coords, nn[1].dimensions, c);
if (e0 < e1)
Expand Down Expand Up @@ -450,16 +461,75 @@ else if (nn[0].children.size() > nn[1].children.size())
}
}
preferred.children.add(c);
tighten(preferred);
}
tighten(nn[0]);
tighten(nn[1]);
return nn;
}

// Implementation of Quadratic PickSeeds
private RTree<T>.Node[] qPickSeeds(LinkedList<Node> nn)
{
@SuppressWarnings("unchecked")
RTree<T>.Node[] bestPair = new RTree.Node[2];
float maxWaste = -1.0f * Float.MAX_VALUE;
for (Node n1: nn)
{
for (Node n2: nn)
{
if (n1 == n2) continue;
float n1a = getArea(n1.dimensions);
float n2a = getArea(n2.dimensions);
float ja = 1.0f;
for ( int i = 0; i < numDims; i++ )
{
float jc0 = Math.min(n1.coords[i], n2.coords[i]);
float jc1 = Math.max(n1.coords[i] + n1.dimensions[i], n2.coords[i] + n2.dimensions[i]);
ja *= (jc1 - jc0);
}
float waste = ja - n1a - n2a;
if ( waste > maxWaste )
{
maxWaste = waste;
bestPair[0] = n1;
bestPair[1] = n2;
}
}
}
nn.remove(bestPair[0]);
nn.remove(bestPair[1]);
return bestPair;
}

/**
* Implementation of QuadraticPickNext
* @param cc the children to be divided between the new nodes, one item will be removed from this list.
* @param nn the candidate nodes for the children to be added to.
*/
private Node qPickNext(LinkedList<Node> cc, Node[] nn)
{
float maxDiff = -1.0f * Float.MAX_VALUE;
Node nextC = null;
for ( Node c: cc )
{
float n0Exp = getRequiredExpansion(nn[0].coords, nn[0].dimensions, c);
float n1Exp = getRequiredExpansion(nn[1].coords, nn[1].dimensions, c);
float diff = Math.abs(n1Exp - n0Exp);
if (diff > maxDiff)
{
maxDiff = diff;
nextC = c;
}
}
assert (nextC != null) : "No node selected from qPickNext";
cc.remove(nextC);
return nextC;
}

// Implementation of LinearPickSeeds
private RTree<T>.Node[] pickSeeds(LinkedList<Node> nn)
private RTree<T>.Node[] lPickSeeds(LinkedList<Node> nn)
{
RTree<T>.Node[] bestPair = null;
@SuppressWarnings("unchecked")
RTree<T>.Node[] bestPair = new RTree.Node[2];
float bestSep = 0.0f;
for (int i = 0; i < numDims; i++)
{
Expand Down Expand Up @@ -491,8 +561,8 @@ private RTree<T>.Node[] pickSeeds(LinkedList<Node> nn)
Math.abs((dimMinUb - dimMaxLb) / (dimUb - dimLb));
if (sep >= bestSep)
{
bestPair = new RTree.Node[]
{ nMaxLb, nMinUb };
bestPair[0] = nMaxLb;
bestPair[1] = nMinUb;
bestSep = sep;
}
}
Expand All @@ -508,39 +578,51 @@ private RTree<T>.Node[] pickSeeds(LinkedList<Node> nn)
return bestPair;
}

private void tighten(Node n)
/**
* Implementation of LinearPickNext
* @param cc the children to be divided between the new nodes, one item will be removed from this list.
*/
private Node lPickNext(LinkedList<Node> cc)
{
assert(n.children.size() > 0) : "tighten() called on empty node!";
float[] minCoords = new float[numDims];
float[] maxCoords = new float[numDims];
for (int i = 0; i < numDims; i++)
{
minCoords[i] = Float.MAX_VALUE;
maxCoords[i] = Float.MIN_VALUE;
return cc.pop();
}

for (Node c : n.children)
private void tighten(Node... nodes)
{
assert(nodes.length >= 1): "Pass some nodes to tighten!";
for (Node n: nodes) {
assert(n.children.size() > 0) : "tighten() called on empty node!";
float[] minCoords = new float[numDims];
float[] maxCoords = new float[numDims];
for (int i = 0; i < numDims; i++)
{
// we may have bulk-added a bunch of children to a node (eg. in
// splitNode)
// so here we just enforce the child->parent relationship.
c.parent = n;
if (c.coords[i] < minCoords[i])
{
minCoords[i] = c.coords[i];
}
if ((c.coords[i] + c.dimensions[i]) > maxCoords[i])
minCoords[i] = Float.MAX_VALUE;
maxCoords[i] = Float.MIN_VALUE;

for (Node c : n.children)
{
maxCoords[i] = (c.coords[i] + c.dimensions[i]);
// we may have bulk-added a bunch of children to a node (eg. in
// splitNode)
// so here we just enforce the child->parent relationship.
c.parent = n;
if (c.coords[i] < minCoords[i])
{
minCoords[i] = c.coords[i];
}
if ((c.coords[i] + c.dimensions[i]) > maxCoords[i])
{
maxCoords[i] = (c.coords[i] + c.dimensions[i]);
}
}
}
for (int i = 0; i < numDims; i++)
{
// Convert max coords to dimensions
maxCoords[i] -= minCoords[i];
}
System.arraycopy(minCoords, 0, n.coords, 0, numDims);
System.arraycopy(maxCoords, 0, n.dimensions, 0, numDims);
}
for (int i = 0; i < numDims; i++)
{
// Convert max coords to dimensions
maxCoords[i] -= minCoords[i];
}
System.arraycopy(minCoords, 0, n.coords, 0, numDims);
System.arraycopy(maxCoords, 0, n.dimensions, 0, numDims);
}

private RTree<T>.Node chooseLeaf(RTree<T>.Node n, RTree<T>.Entry e)
Expand Down
10 changes: 5 additions & 5 deletions test/com/newbrightidea/util/TestRTree.java
View file
Original file line number Diff line number Diff line change
Expand Up @@ -93,10 +93,10 @@ public void testEmptyResults()
@Test
public void testSplitNodesSmall()
{
RTree<Object> rt = new RTree(2,1,2);
RTree<Object> rt = new RTree(2,1,2, RTree.SeedPicker.QUADRATIC);
float[][] coords = new float[][] { {0.0f, 0.0f}, {1.0f, 1.0f}, {2.0f, 2.0f}, {3.0f, 3.0f} };
float[] dims = new float[]{0.5f, 0.5f};
Object[] entries = new Object[] { new Object(), new Object(), new Object(), new Object() };
Object[] entries = new Object[] { 0, 1, 2, 3 };
for (int i = 0; i < entries.length; i++ )
{
rt.insert(coords[i], dims, entries[i]);
Expand Down Expand Up @@ -264,10 +264,10 @@ class DataObject {

for ( int j = 0; j < 500; j++ )
{
RTree<Integer> tree = new RTree<Integer>(10, 2, 3);
RTree<Integer> tree = new RTree<Integer>(10, 2, 3, RTree.SeedPicker.LINEAR);
List<DataObject> rects = new ArrayList<DataObject>();

for (int i = 0; i < 100; i++) {
for (int i = 0; i < 150; i++) {
rects.add(new DataObject(
new float[]{i, i * 2, i * 3},
new float[]{0, 0, 0},
Expand All @@ -276,7 +276,7 @@ class DataObject {
tree.insert(dataObject.val, dataObject.dim, dataObject.id);
}

for (int i = 0; i < 100; i++) {
for (int i = 0; i < 150; i++) {
DataObject dataObject = rects.get(i);
boolean deleted = tree.delete(dataObject.val, dataObject.dim, dataObject.id);
assert deleted;
Expand Down

0 comments on commit 25ebc2e

Please sign in to comment.