I am trying to reverse-sort a slice of integers in Go.
example := []int{1,25,3,5,4}
sort.Ints(example) // this will give me a slice sorted from 1 to the highest number
How do I sort it so that it goes from highest to lowest? so [25 5 4 3 1]
I have tried this
sort.Sort(sort.Reverse(sort.Ints(keys)))
Source:
However, I am getting the error below
# command-line-arguments
./Roman_Numerals.go:31: sort.Ints(keys) used as value
3 Answers
sort.Ints is a convenient function to sort a couple of ints. Generally you need to implement the sort.Interface interface if you want to sort something and sort.Reverse just returns a different implementation of that interface that redefines the Less method.
Luckily the sort package contains a predefined type called IntSlice that implements sort.Interface:
keys := []int{3, 2, 8, 1}
sort.Sort(sort.Reverse(sort.IntSlice(keys)))
fmt.Println(keys)
package main
import (
"fmt"
"sort"
)
func main() {
example := []int{1, 25, 3, 5, 4}
sort.Sort(sort.Reverse(sort.IntSlice(example)))
fmt.Println(example)
}
Output:
[25 5 4 3 1]
Instead of using two function calls and a cast, you can do it with just sort.Slice:
package main
import (
"fmt"
"sort"
)
func main() {
example := []int{1,25,3,5,4}
sort.Slice(example, func(a, b int) bool {
return example[b] < example[a]
})
fmt.Println(example)
}
