Sorting for Slice using Golang

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golang / sort / slice

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This is a sample script for sorting a slice using Golang. Recently, I had a situation for sorting the coordinates of cells of Spreadsheet. As a test case, it thinks of the situation that the randomized cells are sorted. I think that this can be also used for a table except for Spreadsheet.

Sample slice:

The sample slice is as follows.

ar := []struct {
    row   int
    col   int
    value string
}{
    {0, 0, "A1"},
    {0, 1, "B1"},
    {0, 2, "C1"},
    {1, 0, "A2"},
    {1, 1, "B2"},
    {1, 3, "D2"},
    {2, 0, "A3"},
    {2, 2, "C3"},
}

When each element of above slice is put to a Spreadsheet, it becomes as follows.

At the following sample script, after above element is randomized, the original slice is retrieved.

Sample script 1:

Go Playground

package main

import (
	"fmt"
	"math/rand"
	"sort"
)

func main() {
	// Original slice
	ar := []struct {
		row   int
		col   int
		value string
	}{
		{0, 0, "A1"},
		{0, 1, "B1"},
		{0, 2, "C1"},
		{1, 0, "A2"},
		{1, 1, "B2"},
		{1, 3, "D2"},
		{2, 0, "A3"},
		{2, 2, "C3"},
	}

	fmt.Println(ar)

	// Randomize slice
	// https://stackoverflow.com/a/12267471
	for i := range ar {
		j := rand.Intn(i + 1)
		ar[i], ar[j] = ar[j], ar[i]
	}

	fmt.Println(ar)

	// Sort
	sort.Slice(ar, func(i, j int) bool {
		if ar[i].row < ar[j].row {
			return true
		} else if (ar[i].col < ar[j].col) && (ar[i].row == ar[j].row) {
			return true
		}
		return false
	})

	fmt.Println(ar)
}

Result:

[{0 0 A1} {0 1 B1} {0 2 C1} {1 0 A2} {1 1 B2} {1 3 D2} {2 0 A3} {2 2 C3}]
[{1 3 D2} {1 1 B2} {0 2 C1} {2 0 A3} {2 2 C3} {0 0 A1} {1 0 A2} {0 1 B1}]
[{0 0 A1} {0 1 B1} {0 2 C1} {1 0 A2} {1 1 B2} {1 3 D2} {2 0 A3} {2 2 C3}]

Sample script 2:

When row and col are switched as follows, the transposed result is obtained.

Go Playground

package main

import (
	"fmt"
	"math/rand"
	"sort"
)

func main() {
	// Original slice
	ar := []struct {
		row   int
		col   int
		value string
	}{
		{0, 0, "A1"},
		{0, 1, "B1"},
		{0, 2, "C1"},
		{1, 0, "A2"},
		{1, 1, "B2"},
		{1, 3, "D2"},
		{2, 0, "A3"},
		{2, 2, "C3"},
	}

	fmt.Println(ar)

	// Randomize slice
	// https://stackoverflow.com/a/12267471
	for i := range ar {
		j := rand.Intn(i + 1)
		ar[i], ar[j] = ar[j], ar[i]
	}

	fmt.Println(ar)

	// Sort
	sort.Slice(ar, func(i, j int) bool {
		if ar[i].col < ar[j].col {
			return true
		} else if (ar[i].row < ar[j].row) && (ar[i].col == ar[j].col) {
			return true
		}
		return false
	})

	fmt.Println(ar)
}

Result:

[{0 0 A1} {0 1 B1} {0 2 C1} {1 0 A2} {1 1 B2} {1 3 D2} {2 0 A3} {2 2 C3}]
[{1 3 D2} {1 1 B2} {0 2 C1} {2 0 A3} {2 2 C3} {0 0 A1} {1 0 A2} {0 1 B1}]
[{0 0 A1} {1 0 A2} {2 0 A3} {0 1 B1} {1 1 B2} {0 2 C1} {2 2 C3} {1 3 D2}]

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