zeroshade commented on code in PR #34719:
URL: https://github.com/apache/arrow/pull/34719#discussion_r1154873481
##########
go/arrow/compute/internal/kernels/vector_sort.go:
##########
@@ -0,0 +1,87 @@
+package kernels
+
+import (
+ "bytes"
+ "sort"
+
+ "github.com/apache/arrow/go/v12/arrow"
+ "github.com/apache/arrow/go/v12/arrow/array"
+ "github.com/apache/arrow/go/v12/arrow/compute/internal/exec"
+ "github.com/apache/arrow/go/v12/arrow/memory"
+)
+
+type SortIndicesOptions struct {
+ NullPlacement NullPlacement `compute:"null_placement"`
+}
+
+func (s *SortIndicesOptions) TypeName() string {
+ return "SortIndicesOptions"
+}
+
+type Order int
+
+const (
+ Ascending Order = iota
+ Descending
+)
+
+type NullPlacement int
+
+const (
+ AtStart NullPlacement = iota
+ AtEnd
+)
+
+func GetVectorSortingKernels() []exec.VectorKernel {
+ var base exec.VectorKernel
+ base.CanExecuteChunkWise = true
+ base.OutputChunked = false
+ outType := exec.NewOutputType(arrow.ListOf(arrow.PrimitiveTypes.Int64))
+ kernels := make([]exec.VectorKernel, 0)
+ for _, ty := range primitiveTypes {
+ base.Signature = &exec.KernelSignature{
+ InputTypes: []exec.InputType{exec.NewExactInput(ty)},
+ OutType: outType,
+ }
+ base.ExecFn = sortExec
+ kernels = append(kernels, base)
+ }
+ return kernels
+}
+
+func sortExec(ctx *exec.KernelCtx, batch *exec.ExecSpan, out *exec.ExecResult)
error {
+ // Get the input array from the batch
+ inExecVal := batch.Values[0]
+ inArr := inExecVal.Array
+
+ // Create a slice of indices, initialized to [0, 1, 2, ..., n-1]
+ indices := make([]int, inArr.Len)
+ for i := range indices {
+ indices[i] = i
+ }
+
+ sz := inArr.Type.(arrow.FixedWidthDataType).Bytes()
+
+ // Sort the indices slice based on the values in the input array
+ sort.Slice(indices, func(i, j int) bool {
+ // TODO: not sure what to do here?
+ // compare using scalar comparison?
+ a := inArr.Buffers[1].Buf[indices[i]*sz : (indices[i]+1)*sz]
+ b := inArr.Buffers[1].Buf[indices[j]*sz : (indices[j]+1)*sz]
+ return bytes.Compare(a, b) < 0
+ })
Review Comment:
It might make sense to have a look at
https://github.com/apache/arrow/blob/main/go/arrow/compute/internal/kernels/scalar_comparisons.go
(which implements the less than/equals/greater than/etc.) operations at a
scalar level. I'll try to take another look at this early next week but you
might be able to get an idea from over there on how to tackle this.
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