count words in file

count.go

package main

import (
	"fmt"
	"io/ioutil"
	"regexp"
	"strings"
	"sort"
)

func main() {
	// read whole the file
    content, err := ioutil.ReadFile("simple.txt")
    if err != nil { panic(err) }
    str := string(content)
    words := regexp.MustCompile("\\w+").FindAllString(str, -1)

    dict := make(map[string]int)
    for _, word := range words {
    	word = strings.ToLower(word)
    	if _, ok := dict[word] ; ok {
      		dict[word]++
    	}else{
            dict[word] = 1
    	}
    }

    vs := NewValSorter(dict)
    vs.Sort()

    for i := 0; i < len(vs.Keys); i++ {
    	fmt.Printf("%20s -> ", vs.Keys[i])
    	fmt.Printf("%d\n", vs.Vals[i])
    }
}

type ValSorter struct {
        Keys []string
        Vals []int
}
 
func NewValSorter(m map[string]int) *ValSorter {
        vs := &ValSorter{
                Keys: make([]string, 0, len(m)),
                Vals: make([]int, 0, len(m)),
        }
        for k, v := range m {
                vs.Keys = append(vs.Keys, k)
                vs.Vals = append(vs.Vals, v)
        }
        return vs
}
 
func (vs *ValSorter) Sort() {
        sort.Sort(vs)
}
 
func (vs *ValSorter) Len() int           { return len(vs.Vals) }
func (vs *ValSorter) Less(i, j int) bool { return vs.Vals[i] < vs.Vals[j] }
func (vs *ValSorter) Swap(i, j int) {
        vs.Vals[i], vs.Vals[j] = vs.Vals[j], vs.Vals[i]
        vs.Keys[i], vs.Keys[j] = vs.Keys[j], vs.Keys[i]
}