Added fromBinary constructor to SparseVector

pgvector · Sep 10, 2024 · 381afd5 · 381afd5
1 parent 1339791
commit 381afd5
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Showing 2 changed files with 27 additions and 1 deletion.
diff --git a/lib/sparsevec.dart b/lib/sparsevec.dart
@@ -1,3 +1,5 @@
+import 'dart:typed_data';
+
 class SparseVector {
   final int dimensions;
   final List<int> indices;
@@ -18,6 +20,29 @@ class SparseVector {
     return SparseVector._(dimensions, indices, values);
   }
 
+  factory SparseVector.fromBinary(Uint8List bytes) {
+    var bdata = new ByteData.view(bytes.buffer, bytes.offsetInBytes);
+    var dimensions = bdata.getInt32(0);
+    var nnz = bdata.getInt32(4);
+
+    var unused = bdata.getInt32(8);
+    if (unused != 0) {
+      throw FormatException('expected unused to be 0');
+    }
+
+    var indices = <int>[];
+    for (var i = 0; i < nnz; i++) {
+      indices.add(bdata.getInt32(12 + i * 4));
+    }
+
+    var values = <double>[];
+    for (var i = 0; i < nnz; i++) {
+      values.add(bdata.getFloat32(12 + 4 * nnz + i * 4));
+    }
+
+    return SparseVector._(dimensions, indices, values);
+  }
+
   @override
   String toString() {
     var elements = [

diff --git a/test/postgres_test.dart b/test/postgres_test.dart
@@ -36,13 +36,14 @@ void main() {
 
     List<List<dynamic>> results = await connection.execute(
         Sql.named(
-            "SELECT id, embedding FROM items ORDER BY embedding <-> @embedding LIMIT 5"),
+            "SELECT id, embedding, sparse_embedding FROM items ORDER BY embedding <-> @embedding LIMIT 5"),
         parameters: {
           "embedding": Vector([1, 1, 1]).toString()
         });
     for (final row in results) {
       print(row[0]);
       print(Vector.fromBinary(row[1].bytes));
+      print(SparseVector.fromBinary(row[2].bytes));
     }
 
     await connection