Golang : Time slice or date sort and reverse sort example

Sorting time.Time type and dates is pretty straight forward in Golang. Just curious why it is not included in the sort package.

Here’s an example of sorting slice of time.Time in Go.

 package main

 import (
 "fmt"
 "sort"
 "time"
 )

 type timeSlice []time.Time

 func (s timeSlice) Less(i, j int) bool { return s[i].Before(s[j]) }
 func (s timeSlice) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
 func (s timeSlice) Len() int { return len(s) }

 var past = time.Date(2010, time.May, 18, 23, 0, 0, 0, time.Now().Location())
 var present = time.Now()
 var future = time.Now().Add(24 * time.Hour)

 var dateSlice timeSlice = []time.Time{present, future, past}

 func main() {

 fmt.Println("Past : ", past)
 fmt.Println("Present : ", present)
 fmt.Println("Future : ", future)

 fmt.Println("Before sorting : ", dateSlice)

 sort.Sort(dateSlice)

 fmt.Println("After sorting : ", dateSlice)

 sort.Sort(sort.Reverse(dateSlice))

 fmt.Println("After REVERSE sorting : ", dateSlice)

 }

Sample output :

Past : 2010-05-18 23:00:00 +0800 SGT

Present : 2015-08-04 10:57:34.019368428 +0800 SGT

Future : 2015-08-05 10:57:34.019368476 +0800 SGT

Before sorting : [2015-08-04 10:57:34.019368428 +0800 SGT 2015-08-05 10:57:34.019368476 +0800 SGT 2010-05-18 23:00:00 +0800 SGT]

After sorting : [2010-05-18 23:00:00 +0800 SGT 2015-08-04 10:57:34.019368428 +0800 SGT 2015-08-05 10:57:34.019368476 +0800 SGT]

After REVERSE sorting : [2015-08-05 10:57:34.019368476 +0800 SGT 2015-08-04 10:57:34.019368428 +0800 SGT 2010-05-18 23:00:00 +0800 SGT]

Reference :

http://grokbase.com/t/gg/golang-nuts/136mm2bf2m/go-nuts-sort-timeslice

https://www.socketloop.com/tutorials/golang-sort-and-reverse-sort-a-slice-of-strings