使い方: https://www2.adst.keio.ac.jp/rcs/topMenu の中身を投げ込む（POSTなのでChromeはCtrl+Sで保存できないので注意）

gpa.go

package main

import (
	"fmt"
	"github.com/PuerkitoBio/goquery"
	"os"
	"strconv"
)

func gradeToScore(grade string) float64 {
	if grade == "Ａ" {
		return 4.0
	} else if grade == "Ｂ" {
		return 3.0
	} else if grade == "Ｃ" {
		return 2.0
	} else if grade == "Ｄ" {
		return 0.0
	} else if grade == "★" {
		return 0.0
	} else {
		fmt.Println("Error: invalid grade", grade)
		os.Exit(1)
		return -1.0
	}
}

func ignoreGrade(grade string) bool {
	return false
	// この行をコメントアウトして外部向け成績表GPAに
	// return grade == "Ｄ" || grade == "★"
}

func main() {
	if len(os.Args) != 2 {
		fmt.Println("Usage:", os.Args[0], "<foo.html>")
		return
	}
	f, err := os.Open(os.Args[1])
	if err != nil {
		fmt.Println(err)
		return
	}
	defer f.Close()

	doc, err := goquery.NewDocumentFromReader(f)
	if err != nil {
		fmt.Println(err)
		return
	}

	var numer float64
	var denom float64

	doc.Find("tr").Each(func(_ int, s *goquery.Selection) {
		tds := s.Find("td")
		if tds.Length() != 8 {
			return
		}

		var grade float64
		var degree float64
		var ignored bool = false

		tds.Each(func(i int, s *goquery.Selection) {
			t := s.Text()
			if i == 2 {
				grade = gradeToScore(t)
				ignored = ignoreGrade(t)
			} else if i == 3 {
				degree, err = strconv.ParseFloat(t, 64)
				if err != nil {
					fmt.Println("Error: cannot parse float", t)
					os.Exit(1)
				}
			}
		})

		if !ignored {
			numer += grade * degree
			denom += degree
		}
	})

	gpa := numer / denom

	fmt.Println("GPA:", gpa)
}