sparse

package main

import (
	"fmt"
	"strconv"
	"unsafe"

	"github.com/Omniverse-AE/parquet-go/sparse"
)

func main() {
	buf := make([][2]string, 10)
	dst := make([]string, 10)
	src := sparse.UnsafeStringArray(unsafe.Pointer(&buf[0][1]), len(buf), unsafe.Sizeof(buf[0]))

	for i := range buf {
		buf[i][0] = "-"
		buf[i][1] = strconv.Itoa(i)
	}

	n := sparse.GatherString(dst, src)

	for i, v := range dst[:n] {
		fmt.Printf("points[%d].Y = %v\n", i, v)
	}

}

Output:

points[0].Y = 0
points[1].Y = 1
points[2].Y = 2
points[3].Y = 3
points[4].Y = 4
points[5].Y = 5
points[6].Y = 6
points[7].Y = 7
points[8].Y = 8
points[9].Y = 9

package main

import (
	"encoding/binary"
	"fmt"
	"math"
	"unsafe"

	"github.com/Omniverse-AE/parquet-go/sparse"
)

func main() {
	type point2D struct{ X, Y [16]byte }

	buf := make([]point2D, 10)
	dst := make([][16]byte, 10)
	src := sparse.UnsafeUint128Array(unsafe.Pointer(&buf[0].Y), len(buf), unsafe.Sizeof(buf[0]))

	for i := range buf {
		x := uint64(math.MaxUint64)
		y := uint64(2 * i)
		binary.LittleEndian.PutUint64(buf[i].X[:], x)
		binary.LittleEndian.PutUint64(buf[i].Y[:], y)
	}

	n := sparse.GatherUint128(dst, src)

	for i, v := range dst[:n] {
		fmt.Printf("points[%d].Y = %v\n", i, binary.LittleEndian.Uint64(v[:]))
	}

}

Output:

points[0].Y = 0
points[1].Y = 2
points[2].Y = 4
points[3].Y = 6
points[4].Y = 8
points[5].Y = 10
points[6].Y = 12
points[7].Y = 14
points[8].Y = 16
points[9].Y = 18

package main

import (
	"fmt"
	"math"
	"unsafe"

	"github.com/Omniverse-AE/parquet-go/sparse"
)

func main() {
	type point2D struct{ X, Y uint32 }

	buf := make([]point2D, 10)
	dst := make([]uint32, 10)
	src := sparse.UnsafeUint32Array(unsafe.Pointer(&buf[0].Y), len(buf), unsafe.Sizeof(buf[0]))

	for i := range buf {
		buf[i].X = math.MaxUint32
		buf[i].Y = uint32(2 * i)
	}

	n := sparse.GatherUint32(dst, src)

	for i, v := range dst[:n] {
		fmt.Printf("points[%d].Y = %d\n", i, v)
	}

}

Output:

points[0].Y = 0
points[1].Y = 2
points[2].Y = 4
points[3].Y = 6
points[4].Y = 8
points[5].Y = 10
points[6].Y = 12
points[7].Y = 14
points[8].Y = 16
points[9].Y = 18

package main

import (
	"fmt"
	"math"
	"unsafe"

	"github.com/Omniverse-AE/parquet-go/sparse"
)

func main() {
	type point2D struct{ X, Y uint64 }

	buf := make([]point2D, 10)
	dst := make([]uint64, 10)
	src := sparse.UnsafeUint64Array(unsafe.Pointer(&buf[0].Y), len(buf), unsafe.Sizeof(buf[0]))

	for i := range buf {
		buf[i].X = math.MaxUint64
		buf[i].Y = uint64(2 * i)
	}

	n := sparse.GatherUint64(dst, src)

	for i, v := range dst[:n] {
		fmt.Printf("points[%d].Y = %v\n", i, v)
	}

}

Output:

points[0].Y = 0
points[1].Y = 2
points[2].Y = 4
points[3].Y = 6
points[4].Y = 8
points[5].Y = 10
points[6].Y = 12
points[7].Y = 14
points[8].Y = 16
points[9].Y = 18