在字符串

Question

我想在某个主题标签（字符串）之后读取和写入成绩（数字）。所以我有一切，但我无法弄清楚如何找到标签并在不替换后面的数字后写。

因此，例如，有效输入将是：

MAT54324524342211

到目前为止我尝试过的事情：

save = open("grades.txt", "w")

def add(x, y):
    z = x / y * 100
    return z

def calc_grade(perc):
    if perc < 50:
        return "1"
    if perc <  60:
        return "2"
    if perc < 75:
        return "3"
    if perc < 90:
        return "4"
    if perc >= 90:
        return "5"

def calc_command():
    num1 = input("Input your points: ")
    num2 = input("Input maximum points: ")
    num3 = add(float(num1), float(num2))
    grade = calc_grade(num3)
    print("This is your result:", str(num3) + "%")
    print("Your grade:", grade)
    save.write(grade)


while True:
    command = input("Input your command: ")
    if command == "CALC":
        calc_command()
    if command == "EXIT":
        break

有什么想法吗？ 嘿抱歉这是我的代码的旧版本。新版本是在打印后我的成绩是save.write（等级）。程序尚未完成。最后的想法是，我将在我的txt文件中获得一堆主题标签，然后用户将选择哪个主题是成绩。

Answer 1

请尽量不重新实现标准库中已有的内容。

使用json对脚本进行一些实现将是：

import os
import json


def read_grades(filename):
    if os.path.exists(filename):
        with open(filename, 'r') as f:
            try:
                return json.loads(f.read())
            except ValueError as ex:
                print('could not read', ex)
    return {}


def write_grades(filename, grades):
    with open(filename, 'w') as f:
        try:
            f.write(
                json.dumps(grades, indent=2, sort_keys=True)
            )
        except TypeError as ex:
            print('could not write', ex)


def question(text, cast=str):
    try:
        inp = input(text)
        return cast(inp)
    except Exception as ex:
        print('input error', ex)
        return question(text, cast=cast)


def calculator(grades):
    def add(x, y):
        assert y != 0, 'please don\'t do that'
        z = x / y
        return z * 100

    def perc(res):
        for n, p in enumerate([50, 60, 75, 90], start=1):
            if res < p:
                return n
        return 5

    subject = question('enter subject: ').strip()
    points = question('your points: ', cast=float)
    max_points = question('maximum points: ', cast=float)

    result = add(points, max_points)
    grade = perc(result)

    print('> {subject} result: {result:.2f}% grade: {grade}'.format(
        subject=subject.capitalize(),
        result=result, grade=grade
    ))

    grades.setdefault(subject.lower(), list())
    grades[subject.lower()].append(grade)

    return grades


def show(grades):
    print('>> grades')
    for subject in sorted(grades.keys()):
        print('> {subject}: {grades}'.format(
            subject=subject.capitalize(),
            grades='; '.join(str(g) for g in grades[subject])
        ))


def main():
    filename = 'grades.json'
    grades = read_grades(filename)

    while True:

        grades = calculator(grades)
        show(grades)

        if not question('continue? (hit enter to quit) '):
            break

    write_grades(filename, grades)

if __name__ == '__main__':
    main()

grades.json现在包含一个dictionary，主题为主键，所有等级中list为值：

{
  "art": [
    3
  ],
  "math": [
    4,
    5
  ]
}