Vector hash speed up

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelog
 
+## 13.12.6
+- `Vector.hashCode`:
+  - Make hash code more reliable
+
 ## 13.12.5
 - `Vector.randomFilled`:
   - factory-constructor speed-up

benchmark/vector/float32/vector_initializing/float32x4_filled.dart

@@ -1,4 +1,4 @@
-// Approx. 0.23 second (MacBook Pro 2019), Dart version: 2.16.0
+// Approx. 0.23 second (MacBook Pro 2019), Dart version: 3.2.4
 
 import 'package:benchmark_harness/benchmark_harness.dart';
 import 'package:ml_linalg/vector.dart';

benchmark/vector/float32/vector_initializing/float32x4_from_list.dart

@@ -1,4 +1,4 @@
-// Approx. 0.62 second (MacBook Pro 2019), Dart version: 2.16.0
+// Approx. 0.62 second (MacBook Pro 2019), Dart version: 3.2.4
 // Approx. 3.7 second (MacBook Air mid 2017), Dart VM version: 2.16.0
 
 import 'package:benchmark_harness/benchmark_harness.dart';

benchmark/vector/float32/vector_operations/float32x4_vector_hash_code.dart

@@ -1,5 +1,4 @@
-// Approx. 1.9 seconds (MacBook Pro 2019), Dart version: 2.16.0
-// creation + hash code calculation: approx. 2.9 seconds (MacBook Air mid 2017) Dart 2.16.0
+// Approx. 2.5 seconds (MacBook Pro 2019), Dart version: 3.2.4
 
 import 'package:benchmark_harness/benchmark_harness.dart';
 import 'package:ml_linalg/dtype.dart';
@@ -11,21 +10,24 @@ class Float32x4VectorHashCodeBenchmark extends BenchmarkBase {
   Float32x4VectorHashCodeBenchmark()
       : super('Vector `hashCode`; $amountOfElements elements');
 
-  Vector? vector;
+  List<num> source = Vector.randomFilled(
+    amountOfElements,
+    seed: 1,
+    min: -1000,
+    max: 1000,
+    dtype: DType.float32,
+  ).toList();
 
   static void main() {
     Float32x4VectorHashCodeBenchmark().report();
   }
 
   @override
   void run() {
-    Vector.randomFilled(
-      amountOfElements,
-      seed: 1,
-      min: -1000,
-      max: 1000,
+    Vector.fromList(
+      source,
       dtype: DType.float32,
-    ).hashCode;
+    );
   }
 }
 

lib/src/vector/float32x4_vector.dart

@@ -118,6 +118,7 @@ class Float32x4Vector with IterableMixin<double> implements Vector {
   final SimdHelper<Float32x4> _simdHelper;
   late ByteBuffer _buffer;
   late int _numOfBuckets;
+  int _hash = 0;
 
   @override
   Iterator<double> get iterator => _getTypedList().iterator;
@@ -154,18 +155,24 @@ class Float32x4Vector with IterableMixin<double> implements Vector {
   }
 
   @override
-  int get hashCode => _cache.get(vectorHashKey, () {
-        if (isEmpty) {
-          return 0;
-        }
+  int get hashCode {
+    if (isEmpty) {
+      return 0;
+    }
+
+    if (_hash != 0) {
+      return _hash;
+    }
 
-        var i = 0;
+    _hash = 1;
+    final typesList = _getTypedList();
 
-        final summed = _getSimdList()
-            .reduce((sum, element) => sum + element.scale((31 * (i++)) * 1.0));
+    for (var i = 0; i < length; i++) {
+      _hash = _hash * 31 + typesList[i].hashCode;
+    }
 
-        return length + _simdHelper.sumLanesForHash(summed).hashCode;
-      }, skipCaching: false);
+    return _hash;
+  }
 
   @override
   Vector operator +(Object value) {

lib/src/vector/float64x2_vector.g.dart

@@ -121,6 +121,7 @@ class Float64x2Vector with IterableMixin<double> implements Vector {
   final SimdHelper<Float64x2> _simdHelper;
   late ByteBuffer _buffer;
   late int _numOfBuckets;
+  int _hash = 0;
 
   @override
   Iterator<double> get iterator => _getTypedList().iterator;
@@ -157,18 +158,24 @@ class Float64x2Vector with IterableMixin<double> implements Vector {
   }
 
   @override
-  int get hashCode => _cache.get(vectorHashKey, () {
-        if (isEmpty) {
-          return 0;
-        }
+  int get hashCode {
+    if (isEmpty) {
+      return 0;
+    }
+
+    if (_hash != 0) {
+      return _hash;
+    }
 
-        var i = 0;
+    _hash = 1;
+    final typesList = _getTypedList();
 
-        final summed = _getSimdList()
-            .reduce((sum, element) => sum + element.scale((31 * (i++)) * 1.0));
+    for (var i = 0; i < length; i++) {
+      _hash = _hash * 31 + typesList[i].hashCode;
+    }
 
-        return length + _simdHelper.sumLanesForHash(summed).hashCode;
-      }, skipCaching: false);
+    return _hash;
+  }
 
   @override
   Vector operator +(Object value) {

pubspec.yaml

@@ -1,6 +1,6 @@
 name: ml_linalg
 description: SIMD-based linear algebra and statistics, efficient manipulation with numeric data
-version: 13.12.5
+version: 13.12.6
 homepage: https://github.com/gyrdym/ml_linalg
 
 environment: