1. Tools

import (
    "encoding/json"
    "math"
    "sort"
    "strconv"
    "strings"
    "time"
)
// TODO 泛型
func GetMapAllKey(m map[string]interface{}) []string {
    list := make([]string, 0, len(m))
    for key := range m {
        list = append(list, key)
    }
    return list
}

func GetMapAllContent(m map[string]interface{}) []interface{} {
    list := make([]interface{}, 0, len(m))
    for key := range m {
        list = append(list, m[key])
    }
    return list
}

func StructToMap(s interface{}) (ret_map map[string]interface{}) {
    str, err := json.Marshal(s)
    if err != nil {
        panic(err)
    }
    err = json.Unmarshal([]byte(str), &ret_map)
    return ret_map
}

func GetMapKeysAndValues(m map[string]interface{}) (keys []string, values []interface{}) {
    for key := range m {
        keys = append(keys, key)
        values = append(values, m[key])
    }
    return keys, values
}

// 对map 按照key 排序

func RankByWordCount(wordFrequencies map[string]int, ascending bool) PairList {
    pl := make(PairList, len(wordFrequencies))
    i := 0
    for k, v := range wordFrequencies {
        pl[i] = Pair{k, v}
        i++
    }
    //从小到大排序
    //sort.Sort(pl)
    //从大到小排序
    if ascending {
        sort.Sort(pl)
    } else {
        sort.Sort(sort.Reverse(pl))
    }
    return pl
}

type Pair struct {
    Key   string
    Value int
}

type PairList []Pair

func (p PairList) Len() int           { return len(p) }
func (p PairList) Less(i, j int) bool { return p[i].Value < p[j].Value }
func (p PairList) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }

func GetTopNKey(m map[string]int, n int) (ret []string) {
    pl := RankByWordCount(m, false)
    for i := 0; i < len(pl) && i < n; i++ {
        ret = append(ret, pl[i].Key)
    }
    return ret
}

//对map按照value排序后返回
func GetAllSortedKey(m map[string]int) (ret []string) {
    pl := RankByWordCount(m, false)
    for i := 0; i < len(pl); i++ {
        ret = append(ret, pl[i].Key)
    }
    return ret
}

//忽略所恶的将字符串转化为数字
func PureAtoi(s string) int {
    i, _ := strconv.Atoi(s)
    return i
}

const (
    YearMonthDay     = "2006-01-02"
    HourMinuteSecond = "15:04:05"
    DefaultLayout    = YearMonthDay + " " + HourMinuteSecond
)

// 默认格式日期字符串转time
func TimeStrToTimeDefault(str string) time.Time {
    parseTime, _ := time.ParseInLocation(DefaultLayout, str, time.Local)
    return parseTime
}

// 时间戳转日期
func TimestampToDate(stamp int64) string {
    thisTime := time.Unix(stamp, 0)
    return thisTime.Format("2006-01-02 15:04:05")
}

// 时间戳转化为年份
func TimestampToYear(stamp int64) string {
    timeStr := TimestampToDate(stamp)
    return strings.Split(timeStr, "-")[0]
}

//将float64转成精确的int64
func Wrap(num float64, retain int) int64 {
    return int64(num * math.Pow10(retain))
}

// 对排序好的字符串列表快速查找字符串是否在其中
func StrInList(target string, str_array []string) bool {
    //sort.Strings(str_array)
    index := sort.SearchStrings(str_array, target)
    if index < len(str_array) && str_array[index] == target {
        return true
    }
    return false
}