Definition of a shuffling algorithm: An algorithm that generates random sorting for a list.
Currently supported shuffle algorithm:
- Fisher–Yates-Knuth
- Scatology
go get -u github.com/golang-infrastructure/go-shuffle
package main
import (
"fmt"
"github.com/golang-infrastructure/go-shuffle"
)
func main() {
// 对切片中的元素shuffle
slice := []int{1, 2, 3, 4, 5}
shuffle.Shuffle(slice)
fmt.Println(slice)
// Output:
// [5 1 2 3 4]
}
package main
import (
"fmt"
"github.com/golang-infrastructure/go-shuffle"
)
func main() {
// shuffle the elements of a two-dimensional matrix
matrix := [][]int{
{1, 2, 3, 4, 5, 6, 7, 8, 9, 10},
{11, 12, 13, 14, 15, 16, 17, 18, 19, 20},
{21, 22, 23, 24, 25, 26, 27, 28, 29, 30},
{31, 32, 33, 34, 35, 36, 37, 38, 39, 40},
}
// Note that errors may be returned, such as a two-dimensional array that cannot be shuffled if each row has different lengths
err := shuffle.ShuffleMatrix(matrix)
if err != nil {
fmt.Println("Shuffle matrix failed: " + err.Error())
return
}
fmt.Println(matrix)
// Output:
// [[11 40 6 23 15 28 4 7 37 21] [29 26 33 5 35 13 22 32 19 34] [31 30 36 20 2 10 24 39 9 27] [16 8 18 14 1 17 38 12 25 3]]
}
Suppose you now have an array:
[1, 2, 3, 4, 5]
Starting from the rightmost coordinate 'len(slice)-1' as' right_index ', randomly select a subscript from '[0, right_index]' each time, swap the value of the selected subscript with 'right_index', and subtract 'right_index' one offset to the left.
Examples of code:
// Use its own independent random number generator to distinguish it from other calls
var standaloneRand = rand.New(rand.NewSource(time.Now().Unix()))
// FisherYatesKnuthShuffle Fisher–Yates-Knuth Shuffle或 算法对一维数组洗牌,O(n)
func FisherYatesKnuthShuffle[T any](slice []T) {
for index := len(slice) - 1; index > 0; index-- {
chooseIndex := standaloneRand.Intn(index + 1)
slice[chooseIndex], slice[index] = slice[index], slice[chooseIndex]
}
}
By extending the above algorithm, we can easily obtain the shuffle algorithm of the matrix. Each row of the matrix is regarded as a concatenated one-dimensional array, and the shuffle algorithm of the matrix is converted into the shufle algorithm of slices. Shufle of slices has already been implemented:
// FisherYatesShuffleMatrix Fisher–Yates-Knuth The shuffle algorithm shuffles the matrix
func FisherYatesShuffleMatrix[T any](matrix [][]T) error {
// Parameter check
if err := check(matrix); err != nil {
return err
}
row, col := len(matrix), len(matrix[0])
for index := row*col - 1; index > 0; index-- {
chooseIndex := standaloneRand.Intn(index + 1)
matrix[index/col][index%col], matrix[chooseIndex/col][chooseIndex%col] = matrix[chooseIndex/col][chooseIndex%col], matrix[index/col][index%col]
}
return nil
}
// You need to ensure that the incoming two-dimensional data is a matrix, otherwise you may cross the panic line later
func check[T any](matrix [][]T) error {
for i := 1; i < len(matrix); i++ {
if len(matrix[i]) != len(matrix[i-1]) {
return ErrMatrixUnavailable
}
}
return nil
}
That is, the rightmost '[0,right_index]' is no longer selected at random based on Fisher-Yates -Knuth, and the details are no longer expanded.