Added EncodeBinary and DecodeBinary methods to SparseVector

CHANGELOG.md

@@ -1,6 +1,7 @@
 ## 0.2.1 (unreleased)
 
 - Added `EncodeBinary` and `DecodeBinary` methods to `Vector`
+- Added `EncodeBinary` and `DecodeBinary` methods to `SparseVector`
 
 ## 0.2.0 (2024-06-25)
 

sparsevec.go

@@ -3,7 +3,9 @@ package pgvector
 import (
 	"database/sql"
 	"database/sql/driver"
+	"encoding/binary"
 	"fmt"
+	"math"
 	"strconv"
 	"strings"
 )
@@ -120,6 +122,47 @@ func (v *SparseVector) Parse(s string) error {
 	return nil
 }
 
+// EncodeBinary encodes a binary representation of a sparse vector.
+func (v SparseVector) EncodeBinary(buf []byte) (newBuf []byte, err error) {
+	buf = binary.BigEndian.AppendUint32(buf, uint32(v.dim))
+	buf = binary.BigEndian.AppendUint32(buf, uint32(len(v.indices)))
+	buf = binary.BigEndian.AppendUint32(buf, 0)
+	for _, v := range v.indices {
+		buf = binary.BigEndian.AppendUint32(buf, uint32(v))
+	}
+	for _, v := range v.values {
+		buf = binary.BigEndian.AppendUint32(buf, math.Float32bits(v))
+	}
+	return buf, nil
+}
+
+// DecodeBinary decodes a binary representation of a sparse vector.
+func (v *SparseVector) DecodeBinary(buf []byte) error {
+	dim := int(binary.BigEndian.Uint32(buf[0:4]))
+	nnz := int(binary.BigEndian.Uint32(buf[4:8]))
+
+	unused := int(binary.BigEndian.Uint32(buf[8:12]))
+	if unused != 0 {
+		return fmt.Errorf("expected unused to be 0")
+	}
+
+	v.dim = int32(dim)
+	v.indices = make([]int32, 0, dim)
+	v.values = make([]float32, 0, dim)
+
+	for i := 0; i < nnz; i++ {
+		offset := 12 + 4*i
+		v.indices = append(v.indices, int32(binary.BigEndian.Uint32(buf[offset:offset+4])))
+	}
+
+	for i := 0; i < nnz; i++ {
+		offset := 12 + 4*nnz + 4*i
+		v.values = append(v.values, math.Float32frombits(binary.BigEndian.Uint32(buf[offset:offset+4])))
+	}
+
+	return nil
+}
+
 // statically assert that SparseVector implements sql.Scanner.
 var _ sql.Scanner = (*SparseVector)(nil)