将切片调整为新顺序

Question

I have a type...

type MyType struct {
    Job       string `json:"Job"`
    Cost      string `json:"Cost"`

}

A slice of this type...

var records []MyType

It is populated as follows...

records = append(records, MyType{Job: 100, Cost:234},)
records = append(records, MyType{Job: 101, Cost:4000},)
records = append(records, MyType{Job: 102, Cost:700},)

I would like to sort the 'rows' by cost descending so...

records[0].Job would equal 101 records[0].Cost would equal 4000

records[1].Job would equal 102 records[1].Cost would equal 700

records[2].Job would equal 100 records[2].Cost would equal 234

In c# i would normally use linq, but I am new to go and not sure how to go about this...

Answer 1

first of all json type is invalid. Cost should be int type

try this code

import (
    "fmt"
    "sort"
)

type Records []MyType

type MyType struct {
    Job  int `json:"Job"`
    Cost int `json:"Cost"`
}

func (r Records) Len() int           { return len(r) }
func (r Records) Swap(i, j int)      { r[i], r[j] = r[j], r[i] }
func (r Records) Less(i, j int) bool { return r[i].Cost > r[j].Cost }

func main() {

    records := make(Records, 0, 1000)
    records = append(records, MyType{Job: 100, Cost: 234})
    records = append(records, MyType{Job: 101, Cost: 4000})
    records = append(records, MyType{Job: 102, Cost: 700})

    sort.Sort(records)
    fmt.Println(records)
}

or without custom slices

type MyType struct {
    Job  int `json:"Job"`
    Cost int `json:"Cost"`
}

func main() {

    records := make([]MyType, 0, 1000)
    records = append(records, MyType{Job: 100, Cost: 234})
    records = append(records, MyType{Job: 101, Cost: 4000})
    records = append(records, MyType{Job: 102, Cost: 700})

    sort.Slice(records, func(i, j int) bool {
        return records[i].Cost > records[j].Cost
    })
    fmt.Println(records)
}

output

[{101 4000} {102 700} {100 234}]

ref https://golang.org/pkg/sort/#Slice