add cosine_similarity

5 files changed, 162 insertions, 0 deletions

diff --git a/searchlib/abi-spec.json b/searchlib/abi-spec.json
index 30f2cb5c6ea..7d6f2f8790c 100644
--- a/searchlib/abi-spec.json
+++ b/searchlib/abi-spec.json
@@ -947,6 +947,7 @@
       "public final com.yahoo.searchlib.rankingexpression.rule.TensorFunctionNode tensorL1Normalize()",
       "public final com.yahoo.searchlib.rankingexpression.rule.TensorFunctionNode tensorL2Normalize()",
       "public final com.yahoo.searchlib.rankingexpression.rule.TensorFunctionNode tensorEuclideanDistance()",
+      "public final com.yahoo.searchlib.rankingexpression.rule.TensorFunctionNode tensorCosineSimilarity()",
       "public final com.yahoo.searchlib.rankingexpression.rule.TensorFunctionNode tensorMatmul()",
       "public final com.yahoo.searchlib.rankingexpression.rule.TensorFunctionNode tensorSoftmax()",
       "public final com.yahoo.searchlib.rankingexpression.rule.TensorFunctionNode tensorXwPlusB()",
@@ -1100,6 +1101,7 @@
       "public static final int L1_NORMALIZE",
       "public static final int L2_NORMALIZE",
       "public static final int EUCLIDEAN_DISTANCE",
+      "public static final int COSINE_SIMILARITY",
       "public static final int MATMUL",
       "public static final int SOFTMAX",
       "public static final int XW_PLUS_B",
diff --git a/searchlib/src/main/javacc/RankingExpressionParser.jj b/searchlib/src/main/javacc/RankingExpressionParser.jj
index 744e629893e..41647a5ef5b 100755
--- a/searchlib/src/main/javacc/RankingExpressionParser.jj
+++ b/searchlib/src/main/javacc/RankingExpressionParser.jj
@@ -139,6 +139,7 @@ TOKEN :
     <L1_NORMALIZE: "l1_normalize"> |
     <L2_NORMALIZE: "l2_normalize"> |
     <EUCLIDEAN_DISTANCE: "euclidean_distance"> |
+    <COSINE_SIMILARITY: "cosine_similarity"> |
     <MATMUL: "matmul"> |
     <SOFTMAX: "softmax"> |
     <XW_PLUS_B: "xw_plus_b"> |
@@ -381,6 +382,7 @@ TensorFunctionNode tensorFunction() :
         tensorExpression = tensorL1Normalize() |
         tensorExpression = tensorL2Normalize() |
         tensorExpression = tensorEuclideanDistance() |
+        tensorExpression = tensorCosineSimilarity() |
         tensorExpression = tensorMatmul() |
         tensorExpression = tensorSoftmax() |
         tensorExpression = tensorXwPlusB() |
@@ -558,6 +560,18 @@ TensorFunctionNode tensorEuclideanDistance() :
                                                           dimension)); }
 }
 
+TensorFunctionNode tensorCosineSimilarity() :
+{
+    ExpressionNode tensor1, tensor2;
+    String dimension;
+}
+{
+    <COSINE_SIMILARITY> <LBRACE> tensor1 = expression() <COMMA> tensor2 = expression() <COMMA> dimension = identifier() <RBRACE>
+    { return new TensorFunctionNode(new CosineSimilarity(TensorFunctionNode.wrap(tensor1),
+                                                          TensorFunctionNode.wrap(tensor2),
+                                                          dimension)); }
+}
+
 TensorFunctionNode tensorMatmul() :
 {
     ExpressionNode tensor1, tensor2;
@@ -716,6 +730,7 @@ String tensorFunctionName() :
     ( <L1_NORMALIZE> { return token.image; } ) |
     ( <L2_NORMALIZE> { return token.image; } ) |
     ( <EUCLIDEAN_DISTANCE> { return token.image; } ) |
+    ( <COSINE_SIMILARITY> { return token.image; } ) |
     ( <MATMUL>       { return token.image; } ) |
     ( <SOFTMAX>      { return token.image; } ) |
     ( <XW_PLUS_B>    { return token.image; } ) |
diff --git a/vespajlib/abi-spec.json b/vespajlib/abi-spec.json
index 3b9f494dc50..7f70deb0991 100644
--- a/vespajlib/abi-spec.json
+++ b/vespajlib/abi-spec.json
@@ -1705,6 +1705,22 @@
     ],
     "fields" : [ ]
   },
+  "com.yahoo.tensor.functions.CosineSimilarity" : {
+    "superClass" : "com.yahoo.tensor.functions.CompositeTensorFunction",
+    "interfaces" : [ ],
+    "attributes" : [
+      "public"
+    ],
+    "methods" : [
+      "public void <init>(com.yahoo.tensor.functions.TensorFunction, com.yahoo.tensor.functions.TensorFunction, java.lang.String)",
+      "public java.util.List arguments()",
+      "public com.yahoo.tensor.functions.TensorFunction withArguments(java.util.List)",
+      "public com.yahoo.tensor.functions.PrimitiveTensorFunction toPrimitive()",
+      "public java.lang.String toString(com.yahoo.tensor.functions.ToStringContext)",
+      "public int hashCode()"
+    ],
+    "fields" : [ ]
+  },
   "com.yahoo.tensor.functions.Diag" : {
     "superClass" : "com.yahoo.tensor.functions.CompositeTensorFunction",
     "interfaces" : [ ],
diff --git a/vespajlib/src/main/java/com/yahoo/tensor/functions/CosineSimilarity.java b/vespajlib/src/main/java/com/yahoo/tensor/functions/CosineSimilarity.java
new file mode 100644
index 00000000000..ede0355a3a6
--- /dev/null
+++ b/vespajlib/src/main/java/com/yahoo/tensor/functions/CosineSimilarity.java
@@ -0,0 +1,63 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.tensor.functions;
+
+import com.yahoo.tensor.evaluation.Name;
+
+import java.util.Collections;
+import java.util.List;
+import java.util.Objects;
+
+/**
+ * Convenience for cosine similarity between vectors.
+ * cosine_similarity(a, b, mydim) == sum(a*b, mydim) / sqrt(sum(a*a, mydim) * sum(b*b, mydim))
+ * @author arnej
+ */
+public class CosineSimilarity<NAMETYPE extends Name> extends CompositeTensorFunction<NAMETYPE> {
+
+    private final TensorFunction<NAMETYPE> arg1;
+    private final TensorFunction<NAMETYPE> arg2;
+    private final String dimension;
+
+    public CosineSimilarity(TensorFunction<NAMETYPE> argument1,
+                            TensorFunction<NAMETYPE> argument2,
+                            String dimension)
+    {
+        this.arg1 = argument1;
+        this.arg2 = argument2;
+        this.dimension = dimension;
+    }
+
+    @Override
+    public List<TensorFunction<NAMETYPE>> arguments() { return List.of(arg1, arg2); }
+
+    @Override
+    public TensorFunction<NAMETYPE> withArguments(List<TensorFunction<NAMETYPE>> arguments) {
+        if ( arguments.size() != 2)
+            throw new IllegalArgumentException("CosineSimilarity must have 2 arguments, got " + arguments.size());
+        return new CosineSimilarity<>(arguments.get(0), arguments.get(1), dimension);
+    }
+
+    @Override
+    public PrimitiveTensorFunction<NAMETYPE> toPrimitive() {
+        TensorFunction<NAMETYPE> a = arg1.toPrimitive();
+        TensorFunction<NAMETYPE> b = arg2.toPrimitive();
+        var aa = new Join<>(a, a, ScalarFunctions.multiply());
+        var ab = new Join<>(a, b, ScalarFunctions.multiply());
+        var bb = new Join<>(b, b, ScalarFunctions.multiply());
+        var dot_aa = new Reduce<>(aa, Reduce.Aggregator.sum, dimension);
+        var dot_ab = new Reduce<>(ab, Reduce.Aggregator.sum, dimension);
+        var dot_bb = new Reduce<>(bb, Reduce.Aggregator.sum, dimension);
+        var aabb = new Join<>(dot_aa, dot_bb, ScalarFunctions.multiply());
+        var sqrt_aabb = new Map<>(aabb, ScalarFunctions.sqrt());
+        return new Join<>(dot_ab, sqrt_aabb, ScalarFunctions.divide());
+    }
+
+    @Override
+    public String toString(ToStringContext<NAMETYPE> context) {
+        return "cosine_similarity(" + arg1.toString(context) + ", " + arg2.toString(context) + ", " + dimension + ")";
+    }
+
+    @Override
+    public int hashCode() { return Objects.hash("cosine_similarity", arg1, arg2, dimension); }
+
+}
diff --git a/vespajlib/src/test/java/com/yahoo/tensor/functions/CosineSimilarityTestCase.java b/vespajlib/src/test/java/com/yahoo/tensor/functions/CosineSimilarityTestCase.java
new file mode 100644
index 00000000000..b303e2c1739
--- /dev/null
+++ b/vespajlib/src/test/java/com/yahoo/tensor/functions/CosineSimilarityTestCase.java
@@ -0,0 +1,66 @@
+// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+package com.yahoo.tensor.functions;
+
+import com.yahoo.tensor.Tensor;
+import com.yahoo.tensor.TensorType;
+import com.yahoo.tensor.evaluation.VariableTensor;
+import org.junit.Test;
+
+import java.util.List;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * @author arnej
+ */
+public class CosineSimilarityTestCase {
+
+    @Test
+    public void testVectorSimilarity() {
+        var a = Tensor.from("tensor(x[3]):[ 2.0,  3.0, 6.0]");
+        var b = Tensor.from("tensor(x[3]):[-2.0,  0.0, 0.0]");
+        var c = Tensor.from("tensor(x[3]):[ 0.0,  4.0, 3.0]");
+        var op = new CosineSimilarity<>(new ConstantTensor<>(a), new ConstantTensor<>(b), "x");
+        Tensor result = op.evaluate();
+        assertEquals((-2.0 / 7.0), result.asDouble(), 0.000001);
+        op = new CosineSimilarity<>(new ConstantTensor<>(b), new ConstantTensor<>(a), "x");
+        result = op.evaluate();
+        assertEquals((-2.0 / 7.0), result.asDouble(), 0.000001);
+        op = new CosineSimilarity<>(new ConstantTensor<>(a), new ConstantTensor<>(c), "x");
+        result = op.evaluate();
+        assertEquals((30.0 / 35.0), result.asDouble(), 0.000001);
+        op = new CosineSimilarity<>(new ConstantTensor<>(b), new ConstantTensor<>(c), "x");
+        result = op.evaluate();
+        assertEquals(0.0, result.asDouble(), 0.000001);
+    }
+
+    @Test
+    public void testSimilarityInMixed() {
+        var a = Tensor.from("tensor(c{},yy[3]):{foo:[3.0, 4.0,  0.0],bar:[0.0, -4.0,  3.0]}");
+        var b = Tensor.from("tensor(c{},yy[3]):{foo:[0.0, 4.0, -3.0],bar:[4.0,  0.0, -3.0]}");
+        var op = new CosineSimilarity<>(new ConstantTensor<>(a), new ConstantTensor<>(b), "yy");
+        Tensor result = op.evaluate();
+        var expect = Tensor.from("tensor(c{}):{foo:0.64,bar:-0.36}");
+        assertEquals(expect, result);
+    }
+
+    @Test
+    public void testExpansion() {
+        var tType = TensorType.fromSpec("tensor(vecdim[128])");
+        var a = new VariableTensor<>("left", tType);
+        var b = new VariableTensor<>("right", tType);
+        var op = new CosineSimilarity<>(a, b, "vecdim");
+        assertEquals("join(" +
+                     ( "reduce(join(left, right, f(a,b)(a * b)), sum, vecdim), " +
+                       "map(" +
+                       ( "join(" +
+                         ( "reduce(join(left, left, f(a,b)(a * b)), sum, vecdim), " +
+                           "reduce(join(right, right, f(a,b)(a * b)), sum, vecdim), " +
+                           "f(a,b)(a * b)), " ) +
+                         "f(a)(sqrt(a))), " ) +
+                       "f(a,b)(a / b)" ) +
+                     ")",
+                     op.toPrimitive().toString());
+    }
+
+}