Math quiz for teachers & students - follow-up

Question

I have been programming a maths quiz that can be used for teachers an I have have been trying to make the code as short as possible so it is easier to understand. If you have seen my previous post you maybe be wondering why I am re-posting as I already have received feedback, when trying to act on this feedback I seemed to have got stuck again.

In my code, there's a lot of prompting the user for an input and then checking to see if it's valid - so I have been trying to turn this into a function.

Now some of you maybe confused as why I am unable to do this as I have already done this with the variable get_bool_input. However, for this desired function, it needs to be used in a different context which is what I am unable to do.

import sys
import random

def get_bool_input(prompt=''):
    while True:
        val = input(prompt).lower()
        if val == 'yes':
            return True
        elif val == 'no':
            return False
        else:
            sys.exit("Not a valid input (yes/no is expected) please try again")

status = input("Are you a teacher or student? Press 1 if you are a student or 2 if you are a teacher")

if status == "1":
    score=0
    name=input("What is your name?")
    print ("Alright",name,"welcome to your maths quiz")

    level_of_difficulty = int(input(("What level of difficulty are you working at?\n"
                                 "Press 1 for low, 2 for intermediate "
                                    "or 3 for high\n")))
    if level_of_difficulty not in (1,2,3):
        sys.exit("That is not a valid level of difficulty, please try again")

    if level_of_difficulty == 3:
        ops = ['+', '-', '*', '/']
    else:
        ops = ['+', '-', '*']

    for question_num in range(1, 11):
        if level_of_difficulty == 1:
            number_1 = random.randrange(1, 10)
            number_2 = random.randrange(1, 10)
        else:
            number_1 = random.randrange(1, 20)
            number_2 = random.randrange(1, 20)

        operation = random.choice(ops)
        maths = round(eval(str(number_1) + operation + str(number_2)),5)
        print('\nQuestion number: {}'.format(question_num))
        print ("The question is",number_1,operation,number_2)

        answer = float(input("What is your answer: "))
        if answer == maths:
            print("Correct")
            score = score + 1
        else:
            print ("Incorrect. The actual answer is",maths)

    if score >5:
        print("Well done you scored",score,"out of 10")
    else:
        print("Unfortunately you only scored",score,"out of 10. Better luck next time")

    class_number = input("Before your score is saved ,are you in class 1, 2 or 3? Press the matching number")
    while class_number not in ("1","2","3"):
        print("That is not a valid class, unfortunately your score cannot be saved, please try again")
        class_number = input("Before your score is saved ,are you in class 1, 2 or 3? Press the matching number")
# I realised that previously if the user entered an invalid class they would have to start the quiz again from the beginning which is quite
    else:
        filename = (class_number + "txt")

        with open(filename, 'a') as f:
            f.write("\n" + str(name) + " scored " + str(score) +  " on difficulty level " + str(level_of_difficulty))

        with open(filename, 'a') as f:
            f = open(filename, "r")
            lines = [line for line in f if line.strip()]
            f.close()
            lines.sort()

        if get_bool_input("Do you wish to view previous results for your class"):
            for line in lines:
                print (line)
        else:
            sys.exit("Thanks for taking part in the quiz, your teacher should discuss your score with you later")

if status == "2":
    class_number = input("Which classes scores would you like to see? Press 1 for class 1, 2 for class 2 or 3 for class 3")
    if class_number not in (1,2,3):
        sys.exit("That is not a valid class")
    filename = (class_number + "txt")
    with open(filename, 'a') as f:
        f = open(filename, "r")
        lines = [line for line in f if line.strip()]
        f.close()
        lines.sort()
        for line in lines:
            print (line)

Answer 1

Helper functions to prompt

Your get_bool_input is not very friendly: it exits on invalid input. It would be better to let the user retry. For that, simply replace the sys.exit with print.

So it seems you need a lot of prompting, often for integer. So add another helper method:

def prompt_int(prompt=''):
    while True:
        val = input(prompt)
        try:
            return int(val)
        except:
            print("Not a valid number, please try again")

Or if you want to limit input to specific choices you can do something like:

def prompt_choice(prompt, choices):
    while True:
        val = input(prompt)
        if val in choices:
            return val
        else:
            print("Not a valid choice, please try again")

Avoid duplicated code

You have some duplicated logic, in many places, for example:

if level_of_difficulty == 1:
    number_1 = random.randrange(1, 10)
    number_2 = random.randrange(1, 10)
else:
    number_1 = random.randrange(1, 20)
    number_2 = random.randrange(1, 20)

When you see repeated code like that, separate in your mind the parts that are the same and the parts that are different, and try to rewrite in a way that the same part is only written once, and replace the changing part with a variable. Like this:

if level_of_difficulty == 1:
    max_number = 10
else:
    max_number = 20
number_1 = random.randrange(1, max_number)
number_2 = random.randrange(1, max_number)

Apply this technique everywhere in your code.

Working with files

What's going on here:

    with open(filename, 'a') as f:
        f = open(filename, "r")
        lines = [line for line in f if line.strip()]
        f.close()
        lines.sort()

Opening a file to append, then inside the with block open the same file for reading? That doesn't make any sense. With the nonsense removed:

with open(filename) as f:
    lines = [line for line in f if line.strip()]
    lines.sort()

Poor naming

Many variable names don't describe their purpose well. For example "status" is hardly a good name for teacher-student choice. Perhaps "role" would be better.