43. Go - Sorts and Custom Sorts

Go built in sort functions can sort default slice variables and also custom ones.

Example: Ints and Strings

package main

import (

    "fmt"

    "sort"

)

func main() {

    numbers := []int{5, 2, 8, 2, 52, 111}

    words := []string{"hello", "die", "pink", "ablw"}

    fmt.Println(numbers)

    fmt.Println(words)

    sort.Ints(numbers)

    sort.Strings(words)

    fmt.Println(numbers)

    fmt.Println(words)

}

Custom Sort: requires giving the type of data we want to sort a list of similar methods of the built in sort functions so they can be of the same interface. https://pkg.go.dev/sort#example-package

Using sort.Sort(Custom(struct))

Example:

package main

import (

    "fmt"

    "sort"

)

type blob struct {

    Size int

    Name string

}

type bySize []blob

type byName []blob

func (a bySize) Len() int           { return len(a) }

func (a bySize) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

func (a bySize) Less(i, j int) bool { return a[i].Size < a[j].Size }

func (a byName) Len() int           { return len(a) }

func (a byName) Swap(i, j int)      { a[i], a[j] = a[j], a[i] }

func (a byName) Less(i, j int) bool { return a[i].Name < a[j].Name }

func main() {

    blob1 := blob{5, "red"}

    blob2 := blob{6, "blue"}

    blob3 := blob{7, "orange"}

    blob4 := blob{8, "white"}

    blob5 := blob{9, "pink"}

    blobs := []blob{blob1, blob2, blob3, blob4, blob5}

    fmt.Println(blobs)

    sort.Sort(bySize(blobs))

    fmt.Println(blobs)

    sort.Sort(byName(blobs))

    fmt.Println(blobs)

}