gyepisam / shuffler

Shuffler is a Go shuffling package with the ability to anchor items by position or relation to other items

# What

Package shuffler shuffles items using the standard Go math/rand.Perm shuffler, which uses the Fisher-Yates algorithm.

# Why

Shuffled items can be anchored by position or relationship to other items. This is particularly useful for market researchers doing surveys but may be useful to others.

# How

Here is a complete example, also found in the example directory:

package main

import (
	"fmt"

	"github.com/gyepisam/shuffler"

	"math/rand"
)

func main() {
	// Lightly edited list of types of shuffles, copied from Wikipedia
	shuffles := []struct {
		name   string
		anchor shuffler.Anchor
	}{
		{"Chemmy", shuffler.None}, //shuffler.None will be shuffled
		{"Corgi", shuffler.None},
		{"Faro", shuffler.None},
		{"Indian", shuffler.None},
		{"Irish", shuffler.ToPrevious},   // ToPrevious will stick to previous item
		{"Mexican", shuffler.ToPrevious}, // anchors can be chained
		{"Mongean", shuffler.None},
		{"Overhand", shuffler.Position}, //Position will keep item in spot
		{"Pile", shuffler.None},
		{"Riffle", shuffler.None},
		{"Stripping", shuffler.ToNext}, //ToNext will anchor it to next item.
		{"Wash", shuffler.None},
		{"Weave", shuffler.Position},
	}

	shuf := shuffler.New()
	for i, shuffle := range shuffles {
		shuf.Add(i, shuffle.anchor)
	}

	indices := shuf.Shuffle(rand.Int63())

	fmt.Println("Sorted list of shuffles:")
	for i, shuffle := range shuffles {
		fmt.Printf("%d %s\n", i, shuffle.name)
	}

	fmt.Println("Shuffled list of shuffles:")
	for _, j := range indices {
		fmt.Printf("%d %s\n", j, shuffles[j].name)
	}
}

# When

Though I have not seen other implementations of shufflers with anchoring, I imagine they've been around for a while. I have written several implementations over the years in various languages.

# Who

Shuffler is written by Gyepi Sam [e-mail]