Golang interface on type

Question

I am new to GO and I am using golang to write a simple type interface. The type is defined as:

type Sequence []float64

and the interface is:

type Stats interface {

        greaterThan(x float64) Sequence
}

The function greaterThan(x float64) should return a new Sequence that is the same as the numbers in the object // except all numbers less than, or equal to, x have been removed.

Here is my try, but it will not compile. I don't know how to fix it. My question is : how can I delete an item from structure type? Should I use a map? (as my try)

package main

import "fmt"

type Sequence []float64

type Stats interface {

        greaterThan(x float64) Sequence
}

func (s Sequence) greaterThan(x float64) Sequence{

    var i int
    var f float64
    set := make(map[float64]int)
    var v = f[i] Sequence

    for i, f := range set{

    for j := 0; j <= len(s); j++ {
        if s[j] <= x {
        delete(set, s[j])
        }
    }
}

    return v
}

func display(s Sequence) {

        fmt.Println("s.greaterThan(2):", s.greaterThan(2))

}

func main() {

        s := Sequence([]float64{1, 2, 3, -1, 6, 3, 2, 1, 0})
        display(s)

}

BTW. as seen here delete takes the map (in your case set), and the key (in your case j) as arguments. So the delete call would look like delete(set, i) not delete(set, s[j]) — Mihai Stancu
– Mihai Stancu, Commented Feb 4, 2014 at 12:22

Volker · Accepted Answer · 2014-02-04 12:23:13Z

4

I'd do it like this:

package main
import "fmt"
type Sequence []float64
type Stats interface {
    greaterThan(x float64) Sequence
}

func (s Sequence) greaterThan(x float64) (ans Sequence) {
    for _, v := range s {
        if v > x {
            ans = append(ans, v)
        }
    }
    return ans
}

func main() {
    s := Sequence{1, 2, 3, -1, 6, 3, 2, 1, 0}
    fmt.Printf("%v\n", s.greaterThan(2))
}

See http://play.golang.org/p/qXi5uE-25v

Most probably you should not delete items from the slice but construct a new one containing only the wanted ones.

Just out of curiosity: What do you want to do with the interface Stat?

answered Feb 4, 2014 at 12:23

Volker

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