quiz.py

import streamlit as st
from datetime import datetime
import time
import random
import math

TIME_LIMIT = 30 #seconds

def answer(ans):
    st.session_state['correct'] = ans
    if ans == 'True':
        #motivate quickfire answers with an exponential decay
        score = (1 * math.exp(-0.05*(time.time()-st.session_state['time_now'])))*10
        st.session_state['score'] = max(1, score)
    else:
        #penalise wrong answers with a negative score
        st.session_state['score'] = -10
    #update the score but don't prevent it from being negative
    st.session_state['total_score'] += st.session_state['score']
    st.session_state['total_score'] = max(0, st.session_state['total_score'])
    
    st.session_state['time_now'] = time.time()
    st.session_state['count'] += 1

def gen_question():
    #randomly choose two numbers in a range, alongside an operator
    operators = ['+','-','//','*']
    a,b = random.randint(1,10), random.randint(1,10)
    op = random.choice(operators)
    
    #construct the question text and evaluate the calculation
    ques = f"What is {a} {op} {b}?"
    ans = eval(f"{a}{op}{b}")

    #we want to avoid duplicate answer options, so use this inelegant solution
    option2 = eval(f"{b}{op}{a}")
    option3 = eval(f"{b-2}{op}{a+5}")
    option4 = eval(f"{b}{op}{a}-{a}")
    while option2 == ans:
       option2 += 1
    while option3 == ans or option3 == option2:
       option3 += 1
    while option4 == ans or option4 == option2 or option4 == option3:
       option4 += 1
    
    return {'question': ques,
            'options': {
            ans: True,
            option2: False,
            option3: False,
            option4: False
            }
            }
        
row = None

#initialise the session state if keys don't yet exist
if 'correct' not in st.session_state.keys():
    st.session_state['correct'] = None
if "quiz_active" not in st.session_state.keys():
    st.session_state["quiz_active"] = False

i,j,_ = st.columns([1,1,5])
if i.button("Start quiz", key='start_quiz', disabled=st.session_state['quiz_active']):
    st.session_state['quiz_active'] = True
    st.session_state['total_score'] = 0
    st.session_state['count'] = 0
    #if 'time_start' not in st.session_state.keys():
    st.session_state['time_start'] = time.time()
    st.session_state['time_now'] = time.time()
    st.session_state['score'] = 0
    st.session_state['correct'] = None
    st.experimental_rerun()
if j.button("End quiz and reset", key='reset', disabled=not st.session_state['quiz_active']):
    st.session_state['total_score'] = 0
    st.session_state['count'] = 0
    st.session_state['correct'] = None
    st.session_state['quiz_active'] = False
    st.session_state['time_start'] = None
    st.experimental_rerun()
if not st.session_state['quiz_active']:
    st.write(f'\n Welcome to the quiz! You have {TIME_LIMIT} seconds to answer as many questions as you can.')

question_empty = st.empty()

d,e,f = st.columns([2,2,6])
with d:
    total_score_empty = st.empty()
with e:
    st.write('')
    answer_empty = st.empty()

if st.session_state['quiz_active']:
    #check for time up upon page update
    if time.time() - st.session_state['time_start'] > TIME_LIMIT:
        st.info(f"Time's up! You scored a total of **{st.session_state['total_score']:.2f}** \
                    and answered **{st.session_state['count']}** questions.")
    else:
        with question_empty:
            with st.container():
                #get a newly generated question with answer options
                row = gen_question()
                
                st.markdown(f"Question {st.session_state['count']+1}: {row['question']}")
                a,b,c = st.columns([2,2,6])

                options = list(row['options'].keys())
                random.shuffle(options)

                #construct the answer buttons, and pass in whether the answer is correct or not in the args
                a.button(f"{options[0]}", on_click=answer, args=(str(row['options'][options[0]]),))
                a.button(f"{options[1]}", on_click=answer, args=(str(row['options'][options[1]]),))
                b.button(f"{options[2]}", on_click=answer, args=(str(row['options'][options[2]]),))
                b.button(f"{options[3]}", on_click=answer, args=(str(row['options'][options[3]]),))
                
                if st.session_state['correct']  == 'True' and st.session_state['count'] > 0:
                    answer_empty.success(f"Question {st.session_state['count']} correct!")
                elif st.session_state['correct'] == 'False' and st.session_state['count'] > 0:
                    answer_empty.error(f"Question {st.session_state['count']} incorrect!")
                total_score_empty.metric('Total score', value=f"{st.session_state['total_score']:.2f}", delta=f"{st.session_state['score']:.2f}")