Go - Sorting
Updated at 2014-03-07 08:44
There are native sorting functionality for strings, integers and floats. Note that sort changes the slice.
package main
import (
"fmt"
"sort"
)
func main() {
strings := []string{"c", "a", "b"}
sort.Strings(strings)
stringsAreSorted := sort.StringsAreSorted(strings)
fmt.Println("Strings:", strings, "are sorted:", stringsAreSorted)
integers := []int{7, 2, 4}
sort.Ints(integers)
intsAreSorted := sort.IntsAreSorted(integers)
fmt.Println("Ints: ", integers, "are sorted:", intsAreSorted)
floats := []float64{1.23, 64.55, -0.23}
sort.Float64s(floats)
floatsAreSorted := sort.Float64sAreSorted(floats)
fmt.Println("Float64s: ", floats, "are sorted:", floatsAreSorted)
}
You can specify custom sorting by implementing sort.Interface. Anything sortable must have Len(), Less() and Swap().
package main
import (
"fmt"
"sort"
)
type ByNameLength []string
func (self ByNameLength) Len() int {
return len(self)
}
func (self ByNameLength) Swap(i, j int) {
self[i], self[j] = self[j], self[i]
}
func (self ByNameLength) Less(i, j int) bool {
return len(self[i]) < len(self[j])
}
func main() {
fruits := []string{"peach", "strawberry", "banana", "kiwi"}
fmt.Println(fruits)
// => [peach strawberry banana kiwi]
sort.Sort(ByNameLength(fruits))
fmt.Println(fruits)
// => [kiwi peach, banana, strawberry]
}
Sorting times can be done in a similar way.
package main
import (
"fmt"
"sort"
"time"
)
// Creating a new time array type that implements `sort.Interface`.
// The new type is used to allow sorting the underlying time array.
type ByTime []time.Time
func (self ByTime) Len() int {
return len(self)
}
func (self ByTime) Swap(i, j int) {
self[i], self[j] = self[j], self[i]
}
func (self ByTime) Less(i, j int) bool {
return self[i].Before(self[j])
}
func main() {
const shortForm = "Jan/02/2006 15:04:05"
t1, _ := time.Parse(shortForm, "Feb/02/2014 00:00:00")
t2, _ := time.Parse(shortForm, "Feb/02/1800 00:00:00")
t3, _ := time.Parse(shortForm, "Feb/02/1999 00:00:00")
t4, _ := time.Parse(shortForm, "Feb/02/2014 00:11:00")
t5, _ := time.Parse(shortForm, "Feb/02/2000 00:00:00")
times := []time.Time{t1, t2, t3, t4, t5}
fmt.Println("Original:")
for _, t := range times {
fmt.Println(t)
}
sort.Sort(ByTime(times))
fmt.Println("\nSorted:")
for _, t := range times {
fmt.Println(t)
}
}