Added SparseVector class

CHANGELOG.md

@@ -1,6 +1,6 @@
 ## 0.1.1 (unreleased)
 
-- Added `Vector` and `HalfVector` classes
+- Added `Vector`, `HalfVector`, and `SparseVector` classes
 
 ## 0.1.0 (2023-10-17)
 

lib/pgvector.dart

@@ -2,9 +2,11 @@ import 'dart:convert';
 import 'dart:typed_data';
 
 import 'halfvec.dart';
+import 'sparsevec.dart';
 import 'vector.dart';
 
 export 'halfvec.dart' show HalfVector;
+export 'sparsevec.dart' show SparseVector;
 export 'vector.dart' show Vector;
 
 class Pgvector {

lib/sparsevec.dart

@@ -0,0 +1,28 @@
+class SparseVector {
+  final int dimensions;
+  final List<int> indices;
+  final List<double> values;
+
+  SparseVector._(this.dimensions, this.indices, this.values);
+
+  factory SparseVector(List<double> value) {
+    var dimensions = value.length;
+    var indices = <int>[];
+    var values = <double>[];
+    for (var i = 0; i < value.length; i++) {
+      if (value[i] != 0) {
+        indices.add(i);
+        values.add(value[i]);
+      }
+    }
+    return SparseVector._(dimensions, indices, values);
+  }
+
+  @override
+  String toString() {
+    var elements = [
+      for (var i = 0; i < indices.length; i++) "${indices[i] + 1}:${values[i]}"
+    ].join(",");
+    return "{${elements}}/${this.dimensions}";
+  }
+}

test/postgres_test.dart

@@ -17,18 +17,21 @@ void main() {
     await connection.execute("DROP TABLE IF EXISTS items");
 
     await connection.execute(
-        "CREATE TABLE items (id bigserial PRIMARY KEY, embedding vector(3), half_embedding halfvec(3))");
+        "CREATE TABLE items (id bigserial PRIMARY KEY, embedding vector(3), half_embedding halfvec(3), sparse_embedding sparsevec(3))");
 
     await connection.execute(
         Sql.named(
-            "INSERT INTO items (embedding, half_embedding) VALUES (@a, @d), (@b, @e), (@c, @f)"),
+            "INSERT INTO items (embedding, half_embedding, sparse_embedding) VALUES (@a, @d, @g), (@b, @e, @h), (@c, @f, @i)"),
         parameters: {
           "a": Vector([1, 1, 1]).toString(),
           "b": Vector([2, 2, 2]).toString(),
           "c": Vector([1, 1, 2]).toString(),
           "d": HalfVector([1, 1, 1]).toString(),
           "e": HalfVector([2, 2, 2]).toString(),
-          "f": HalfVector([1, 1, 2]).toString()
+          "f": HalfVector([1, 1, 2]).toString(),
+          "g": SparseVector([1, 1, 1]).toString(),
+          "h": SparseVector([2, 2, 2]).toString(),
+          "i": SparseVector([1, 1, 2]).toString()
         });
 
     List<List<dynamic>> results = await connection.execute(