(commons-math) branch master updated: Fix Network.getNeighbours deleting links to excluded neurons (#345)

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The following commit(s) were added to refs/heads/master by this push:
     new 54345ef8f Fix Network.getNeighbours deleting links to excluded neurons 
(#345)
54345ef8f is described below

commit 54345ef8fcb755bb4bd467253d3ba36485ac0f58
Author: insaf021 <in...@digiscrypt.com>
AuthorDate: Tue Nov 3 16:29:47 2026 +0530

    Fix Network.getNeighbours deleting links to excluded neurons (#345)
    
    getNeighbours(Neuron, Iterable) removed the excluded identifiers from the
    network's own link set rather than from a copy, so the query deleted the
    links from the neuron to every excluded neuron.
---
 .../apache/commons/math4/neuralnet/Network.java    |  2 +-
 .../commons/math4/neuralnet/NetworkTest.java       | 29 ++++++++++++++++++++++
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git 
a/commons-math-neuralnet/src/main/java/org/apache/commons/math4/neuralnet/Network.java
 
b/commons-math-neuralnet/src/main/java/org/apache/commons/math4/neuralnet/Network.java
index 36d12f30e..957359beb 100644
--- 
a/commons-math-neuralnet/src/main/java/org/apache/commons/math4/neuralnet/Network.java
+++ 
b/commons-math-neuralnet/src/main/java/org/apache/commons/math4/neuralnet/Network.java
@@ -367,7 +367,7 @@ public class Network
      */
     public Collection<Neuron> getNeighbours(Neuron neuron,
                                             Iterable<Neuron> exclude) {
-        final Set<Long> idList = linkMap.get(neuron.getIdentifier());
+        final Set<Long> idList = new 
HashSet<>(linkMap.get(neuron.getIdentifier()));
         if (exclude != null) {
             for (final Neuron n : exclude) {
                 idList.remove(n.getIdentifier());
diff --git 
a/commons-math-neuralnet/src/test/java/org/apache/commons/math4/neuralnet/NetworkTest.java
 
b/commons-math-neuralnet/src/test/java/org/apache/commons/math4/neuralnet/NetworkTest.java
index f959c2a52..a0f861d9c 100644
--- 
a/commons-math-neuralnet/src/test/java/org/apache/commons/math4/neuralnet/NetworkTest.java
+++ 
b/commons-math-neuralnet/src/test/java/org/apache/commons/math4/neuralnet/NetworkTest.java
@@ -108,6 +108,35 @@ public class NetworkTest {
         Assert.assertEquals(1, net.getNeighbours(net.getNeuron(3)).size());
     }
 
+    /*
+     * Test assumes that the network is
+     *
+     *  0-----1
+     *  |     |
+     *  |     |
+     *  2-----3
+     */
+    @Test
+    public void testGetNeighboursWithExcludeDoesNotModifyNetwork() {
+        final FeatureInitializer[] initArray = {init};
+        final Network net = new NeuronSquareMesh2D(2, false,
+                                                   2, false,
+                                                   
SquareNeighbourhood.VON_NEUMANN,
+                                                   initArray).getNetwork();
+        final Neuron n0 = net.getNeuron(0);
+        final Neuron n1 = net.getNeuron(1);
+        final Neuron n2 = net.getNeuron(2);
+
+        // Excluded neuron is not returned.
+        final Collection<Neuron> neighbours = net.getNeighbours(n0, 
Arrays.asList(n1));
+        Assert.assertEquals(1, neighbours.size());
+        Assert.assertTrue(neighbours.contains(n2));
+
+        // Link from 0 to 1 still exists.
+        Assert.assertEquals(2, net.getNeighbours(n0).size());
+        Assert.assertTrue(net.getNeighbours(n0).contains(n1));
+    }
+
     @Test
     public void testIdentifierAssignment() {
         final FeatureInitializer[] initArray = {init};