43: Sorting by custom compare functions

Author: symonk

README.md

@@ -62,3 +62,4 @@ go run . -module closingchannels
 * [40 - Mutexes](mutexes/main.go)
 * [41 - Stateful Goroutines](statefulgoroutines/main.go)
 * [42 - Sorting](sorting/main.go)
+* [43 - SortingByFunctions](sortingbyfunctions/main.go)

main.go

@@ -23,6 +23,7 @@ import (
 	"github.com/symonk/learning-golang/interfaces"
 	"github.com/symonk/learning-golang/maps"
 	"github.com/symonk/learning-golang/methods"
+	"github.com/symonk/learning-golang/mutexes"
 	"github.com/symonk/learning-golang/nonblockingchannelops"
 	"github.com/symonk/learning-golang/pointers"
 	"github.com/symonk/learning-golang/rangeoverchannels"
@@ -31,6 +32,9 @@ import (
 	"github.com/symonk/learning-golang/recursion"
 	"github.com/symonk/learning-golang/selects"
 	"github.com/symonk/learning-golang/slices"
+	"github.com/symonk/learning-golang/sorting"
+	"github.com/symonk/learning-golang/sortingbyfunctions"
+	"github.com/symonk/learning-golang/statefulgoroutines"
 	"github.com/symonk/learning-golang/stringsrunes"
 	"github.com/symonk/learning-golang/structembedding"
 	"github.com/symonk/learning-golang/structs"
@@ -42,9 +46,6 @@ import (
 	"github.com/symonk/learning-golang/variables"
 	"github.com/symonk/learning-golang/waitgroups"
 	"github.com/symonk/learning-golang/workerpools"
-	"github.com/symonk/learning-golang/mutexes"
-	"github.com/symonk/learning-golang/statefulgoroutines"
-	"github.com/symonk/learning-golang/sorting"
 )
 
 func main() {
@@ -114,5 +115,6 @@ func buildMap() map[string]func() {
 	fnMap["mutexes"] = mutexes.Run
 	fnMap["statefulgoroutines"] = statefulgoroutines.Run
 	fnMap["sorting"] = sorting.Run
+	fnMap["sortingbyfunctions"] = sortingbyfunctions.Run
 	return fnMap
 }

sorting/main.go

@@ -28,7 +28,7 @@ type Foo struct {
 
 // Sorting a user defined; custom type
 func sortingCustomType() {
-	foos := []Foo{Foo{x: 3}, Foo{x: 2}, Foo{x: 100}, Foo{x: 1}}
+	foos := []Foo{{x: 3}, {x: 2}, {x: 100}, {x: 1}}
 	sort.Slice(foos[:], func(i, j int) bool {
 		return foos[i].x < foos[j].x
 	})

sortingbyfunctions/main.go

@@ -0,0 +1,25 @@
+package sortingbyfunctions
+
+import (
+	"cmp"
+	"fmt"
+	"slices"
+)
+
+// Often you want to sort by something other than the
+// natural order
+func Run() {
+
+	ints := []int{2, 3, 12, 13, 22, 23}
+	sortingIntegersByOddEven(ints)
+	fmt.Println(ints)
+	// [2, 12, 22, 3, 13, 23]
+}
+
+// Sort our slice in-place by a custom function.
+func sortingIntegersByOddEven(ints []int) {
+	compFn := func(a, b int) int {
+		return cmp.Compare[int](a%2, b%2)
+	}
+	slices.SortFunc(ints, compFn)
+}