Golang 函数链在不同领域的实际应用

import (
    "encoding/csv"
    "fmt"
    "io"
    "log"
    "os"
    "sort"
    "strconv"
)

type Sale struct {
    Region  string
    Amount  float64
}

func main() {
    // 读取文件并解析成结构体
    entries, err := readCSV("sales.csv")
    if err != nil {
        log.Fatal(err)
    }

    // 过滤特定销售区域
    filtered := filterRegion(entries, "Central")

    // 计算每个区域的销售总额
    totals := calculateTotals(filtered)

    // 按销售总额排序
    sort.Slice(totals, func(i, j int) bool {
        return totals[i].Amount < totals[j].Amount
    })

    // 打印结果
    for _, t := range totals {
        fmt.Println(t.Region, t.Amount)
    }
}

func calculateTotals(sales []Sale) []Sale {
    totals := make([]Sale, 0)
    regionTotals := make(map[string]float64)
    for _, s := range sales {
        regionTotals[s.Region] += s.Amount
    }
    for r, t := range regionTotals {
        totals = append(totals, Sale{Region: r, Amount: t})
    }
    return totals
}

func filterRegion(sales []Sale, region string) []Sale {
    filtered := make([]Sale, 0)
    for _, s := range sales {
        if s.Region == region {
            filtered = append(filtered, s)
        }
    }
    return filtered
}

func readCSV(path string) ([]Sale, error) {
    f, err := os.Open(path)
    if err != nil {
        return nil, err
    }
    defer f.Close()

    r := csv.NewReader(f)
    entries := make([]Sale, 0)
    for {
        record, err := r.Read()
        if err == io.EOF {
            return entries, nil
        }
        if err != nil {
            return nil, err
        }
        if len(record) < 3 {
            continue
        }
        val, err := strconv.ParseFloat(record[2], 64)
        if err != nil {
            continue
        }
        entries = append(entries, Sale{Region: record[1], Amount: val})
    }
}

import (
    "fmt"
    "image"
    "log"
    "os"

    "github.com/disintegration/imaging"
)

func main() {
    // 读取图片
    image, err := imaging.Open("image.jpg")
    if err != nil {
        log.Fatal(err)
    }

    // 调整亮度
    img := imaging.AdjustBrightness(image, 20)

    // 锐化
    img = imaging.Sharpen(img, 10)

    // 裁剪
    img = imaging.Crop(img, image.Bounds().Min, image.Bounds().Max.Sub(25).Add(image.Bounds().Min))

    // 保存结果
    err = imaging.Save(img, "result.jpg", imaging.JPEGQuality(80))
    if err != nil {
        log.Fatal(err)
    }
    fmt.Println("Image processed and saved")
}