lancet/docs/mathutil_zh-CN.md

Mathutil

mathutil 包实现了一些数学计算的函数.

源码:

• https://github.com/duke-git/lancet/blob/main/mathutil/mathutil.go

用法:

import (
    "github.com/duke-git/lancet/v2/mathutil"
)

目录

• Average
• Exponent
• Fibonacci
• Factorial
• Max
• MaxBy
• Min
• MinBy
• Percent
• RoundToFloat
• RoundToString
• TruncRound

Documentation

Average

计算平均数. 可能需要对结果调用RoundToFloat方法四舍五入

函数签名:

func Average[T constraints.Integer | constraints.Float](numbers ...T) T

例子:

package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.Average(1, 2)

    avg := mathutil.Average(1.2, 1.4)
    result2 := mathutil.RoundToFloat(avg, 1)

    fmt.Println(result1)
    fmt.Println(result2)

    // Output:
    // 1
    // 1.3
}

Exponent

指数计算（x的n次方）

函数签名:

func Exponent(x, n int64) int64

例子:

package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.Exponent(10, 0)
    result2 := mathutil.Exponent(10, 1)
    result3 := mathutil.Exponent(10, 2)

    fmt.Println(result1)
    fmt.Println(result2)
    fmt.Println(result3)

    // Output:
    // 1
    // 10
    // 100
}

Fibonacci

计算斐波那契数列的第n个数

函数签名:

func Fibonacci(first, second, n int) int

例子:

package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.Fibonacci(1, 1, 1)
    result2 := mathutil.Fibonacci(1, 1, 2)
    result3 := mathutil.Fibonacci(1, 1, 5)

    fmt.Println(result1)
    fmt.Println(result2)
    fmt.Println(result3)

    // Output:
    // 1
    // 1
    // 5
}

Factorial

计算阶乘

函数签名:

func Factorial(x uint) uint

例子:

package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.Factorial(1)
    result2 := mathutil.Factorial(2)
    result3 := mathutil.Factorial(3)

    fmt.Println(result1)
    fmt.Println(result2)
    fmt.Println(result3)

    // Output:
    // 1
    // 2
    // 6
}

Max

返回参数中的最大数

函数签名:

func Max[T constraints.Integer | constraints.Float](numbers ...T) T

例子:

package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.Max(1, 2, 3)
    result2 := mathutil.Max(1.2, 1.4, 1.1, 1.4)

    fmt.Println(result1)
    fmt.Println(result2)

    // Output:
    // 3
    // 1.4
}

MaxBy

使用给定的比较器函数返回切片的最大值

函数签名:

func MaxBy[T any](slice []T, comparator func(T, T) bool) T

例子:

package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.MaxBy([]string{"a", "ab", "abc"}, func(v1, v2 string) bool {
        return len(v1) > len(v2)
    })

    result2 := mathutil.MaxBy([]string{"abd", "abc", "ab"}, func(v1, v2 string) bool {
        return len(v1) > len(v2)
    })

    result3 := mathutil.MaxBy([]string{}, func(v1, v2 string) bool {
        return len(v1) > len(v2)
    })

    fmt.Println(result1)
    fmt.Println(result2)
    fmt.Println(result3)

    // Output:
    // abc
    // abd
    //
}

Min

返回参数中的最小数

函数签名:

func Min[T constraints.Integer | constraints.Float](numbers ...T) T

例子:

package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.Min(1, 2, 3)
    result2 := mathutil.Min(1.2, 1.4, 1.1, 1.4)

    fmt.Println(result1)
    fmt.Println(result2)

    // Output:
    // 1
    // 1.1
}

MinBy

使用给定的比较器函数返回切片的最小值

函数签名:

func MinBy[T any](slice []T, comparator func(T, T) bool) T

例子:

package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.MinBy([]string{"a", "ab", "abc"}, func(v1, v2 string) bool {
        return len(v1) < len(v2)
    })

    result2 := mathutil.MinBy([]string{"ab", "ac", "abc"}, func(v1, v2 string) bool {
        return len(v1) < len(v2)
    })

    result3 := mathutil.MinBy([]string{}, func(v1, v2 string) bool {
        return len(v1) < len(v2)
    })

    fmt.Println(result1)
    fmt.Println(result2)
    fmt.Println(result3)

    // Output:
    // a
    // ab
    //
}

Percent

计算百分比，保留n位小数

函数签名:

func Percent(val, total float64, n int) float64

例子:

package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.Percent(1, 2, 2)
    result2 := mathutil.Percent(0.1, 0.3, 2)

    fmt.Println(result1)
    fmt.Println(result2)

    // Output:
    // 0.5
    // 0.33
}

RoundToFloat

四舍五入，保留n位小数

函数签名:

func RoundToFloat(x float64, n int) float64

例子:

package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.RoundToFloat(0.124, 2)
    result2 := mathutil.RoundToFloat(0.125, 2)
    result3 := mathutil.RoundToFloat(0.125, 3)

    fmt.Println(result1)
    fmt.Println(result2)
    fmt.Println(result3)

    // Output:
    // 0.12
    // 0.13
    // 0.125
}

RoundToString

四舍五入，保留n位小数，返回字符串

函数签名:

func RoundToString(x float64, n int) string

例子:

package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.RoundToString(0.124, 2)
    result2 := mathutil.RoundToString(0.125, 2)
    result3 := mathutil.RoundToString(0.125, 3)

    fmt.Println(result1)
    fmt.Println(result2)
    fmt.Println(result3)

    // Output:
    // 0.12
    // 0.13
    // 0.125
}

TruncRound

截短n位小数（不进行四舍五入）

函数签名:

func TruncRound(x float64, n int) float64

例子:

package main

import (
    "fmt"
    "github.com/duke-git/lancet/v2/mathutil"
)

func main() {
    result1 := mathutil.TruncRound(0.124, 2)
    result2 := mathutil.TruncRound(0.125, 2)
    result3 := mathutil.TruncRound(0.125, 3)

    fmt.Println(result1)
    fmt.Println(result2)
    fmt.Println(result3)

    // Output:
    // 0.12
    // 0.12
    // 0.125
}