python: Adding to username

Question

I am fairly new to python and I need to make a program to ask 10 questions, save the score into a file and allow someone to read the scores in from the file.

My problem: I need to check if the person who has done the quiz already has a record in the file, and if so, I need to add their score to the end of their record.

The records should look like this:

name,score,score,score,score, etc so they can be split using commas.

I am also looking for the simplest answer, not the most efficient. Also, if you could comment the code, it would make it much easier. Here is my code so far:

import random
import math
import operator as op
import sys
import re

def test():
    num1 = random.randint(1, 10)
    num2 = random.randint(1, num1)

    ops = {
        '+': op.add,
        '-': op.sub,
        '*': op.mul,
        }

    keys = list(ops.keys())
    rand_key = random.choice(keys)
    operation = ops[rand_key]

    correct_result = operation(num1, num2)

    print ("What is {} {} {}?".format(num1, rand_key, num2))
    while True:
            try:
                user_answer = int(input("Your answer: "))
            except ValueError:
                print("Only enter numbers!")
                continue
            else:
                break

    if user_answer != correct_result:
        print ("Incorrect. The right answer is {}".format(correct_result))
        return False
    else:
        print("Correct!")
        return True

print("1. Are you a student?")
print("2. Are you a teacher?")
print("3. Exit")

while True:
        try:
            status = int(input("Please select an option:"))
        except ValueError:
            print("Please enter a number!")
        else:
            if status not in {1,2,3}:
                print("Please enter a number in {1,2,3}!")
            else:
                break


if status == 1:

    username=input("What is your name?")
    while not re.match("^[A-Za-z ]*$", username) or username=="":
        username=input(str("Please enter a valid name (it must not contain numbers or symbols)."))
    print ("Hi {}! Wellcome to the Arithmetic quiz...".format(username))

    while True:
        try:
            users_class = int(input("Which class are you in? (1,2 or 3)"))
        except ValueError:
            print("Please enter a number!")
        else:
            if users_class not in {1,2,3}:
                print("Please enter a number in {1,2,3}!")
            else:
                break

    correct_answers = 0
    num_questions = 10

    for i in range(num_questions):
        if test():
            correct_answers +=1

    print("{}: You got {}/{} {} correct.".format(username, correct_answers,  num_questions,
'question' if (correct_answers==1) else 'questions'))


    if users_class == 1:
        class1 = open("Class1.txt", "a+")
        newRecord = username+ "," + str(correct_answers) + "," + "\n"
        class1.write(newRecord)
        class1.close()
    elif users_class == 2:
        class2 = open("Class2.txt", "a+")
        newRecord = username+ "," + str(correct_answers) + "," + "\n"
        class2.write(newRecord)
        class2.close()

    elif users_class == 3:
        class3 = open("Class3.txt", "a+")
        newRecord = username+ "," + str(correct_answers) + "," + "\n"
        class3.write(newRecord)
        class3.close()
    else:
        print("Sorry, we can not save your data as the class you entered is not valid.")

Answer 1

First, define these functions:

from collections import defaultdict
def read_scores(users_class):
    """
    If the score file for users_class does not exist, return an empty 
    defaultdict(list).  If the score file does exist, read it in and return 
    it as a defaultdict(list).  The keys of the dict are the user names, 
    and the values are lists of ints (the scores for each user)
    """
    assert 0 <= users_class <= 3
    result = defaultdict(list)
    try:
        lines =open("Class%d.txt"%users_class,'r').readlines()
    except IOError:
        return result
    for line in lines:
        # this line requires python3
        user, *scores = line.strip().split(',')
        # if you need to use python2, replace the above line
        # with these two lines:
        #    line = line.strip().split(',')
        #    user, scores = line[0], line[1:]
        result[user] = [int(s) for s in scores]
    return result

def write_scores(users_class, all_scores):
    """
    Write user scores to the appropriate file.
    users_class is the class number, all scores is a dict kind of dict
    returned by read_scores.
    """
    f = open("Class%d.txt"%users_class,'w')
    for user, scores in all_scores.items():
        f.write("%s,%s\n"%(user, ','.join([str(s) for s in scores])))

def update_user_score(users_class, user_name, new_score):
    """
    Update the appropriate score file for users_class.
    Append new_score to user_name's existing scores.  If the user has
    no scores, a new record is created for them.
    """
    scores = read_scores(users_class)
    scores[user_name].append(new_score)
    write_scores(users_class, scores)

Now, in the last portion of your code (where you actually write the scores out) becomes much simpler. Here's an example of writing some scores:

update_user_score(1, 'phil', 7)
update_user_score(1, 'phil', 6)
update_user_score(1, 'alice', 6)
update_user_score(1, 'phil', 9)

there will be two lines in Class1.txt: phil,7,6,9 alice,6

We read the whole file into a dict (actually a defaultdict(list)), and overwrite that same file with an updated dict. By using defaultdict(list), we don't have to worry about distinguishing between updating and adding a record.

Note also that we don't need separate if/elif cases to read/write the files. "Scores%d.txt"%users_class gives us the name of the file.

Answer 2

EDIT:

---

Add this function before your "test" function:

def writeUserScore(file, name, score):
  with open (file, "r") as myfile:
    s = myfile.read()

  rows = s.split("\n")
  data = {}
  for row in rows:
    tmp = row.split(",")
    if len(tmp) >= 2: data[tmp[0]] = tmp[1:]

  if name not in data:
    data[name] = []

  data[name].append(str(score))

  output = ""
  for name in data:
    output = output + name + "," + ",".join(data[name]) + "\n"

  handle = open(file, "w+")
  handle.write(output)
  handle.close()

After that, where you have "if users_class == 1:" do this:

writeUserScore("Class1.txt", username, str(correct_answers))

Do the same for the other two else ifs.

Let me know what you think!

---

Try using a dictionary to hold the existing file data.

Read the file in a variable called "str" for example. And then do something like this:

rows = str.split("\n")
data1 = {}
for row in rows:
  tmp = row.split(",")
  data1[tmp[0]] = tmp[1:]

When you have a new score you should then do:

if username not in data1:
  data1[username] = []

data1[username] = str(correct_answers)

And to save the data back to the file:

output = ""
for name in data1:
  output = outupt + name + "," + ",".join(data1[name]) | "\n"

And save the contents of "output" to the file.

PS: If you are not bound by the file format you can use a JSON file. I can tell you more about this if you wish.

Hope that helps, Alex