How to deal with different size lists in python and indexes (List indexes)

Question

Im writing a python script and am confused on some list related logic. I have 2 lists prizeList which contains prize elements, and a winners list containing winner elements. For every element in the winnerList I want to associate a prize element with it.

I have two methods: distributePrizes which contains this logic and sendEmail method which is called from distributePrizes method.

The issue I am having is that when there is not enough prizes for each winner the script stops after the first check.

There are three possible conditions: 1. Enough Prizes for the number of winners. In this case call emailWinners method. 2.Less prizes than there are winners. Call emailWinners for every winner thats matched with a prize. 3. No prizes. In this case output an error.

I am unsure how to call the emailWinners method for every winner matched with a prize. I get index out of bounds errors when trying to call emailWinner for every winner when the prizeList and winnerList are of different sizes.

eg(winnerList[] = length 5, prizeList[] = length 3. Should email 3 winners with prize but instead gets an index out of bounds error.)

Here's what I have tried so far:

 if len(prizeArray) < len(winnerEmail):

    # Not enough prizes for every winner

    print("Not enough prizes for " + prizeType)  # Alert if not enough prizes

    for email in winnerEmail:
        emailUserWithPrize(winnerEmailAddress, winnerPrize)

winnerEmailAddress = ""
winnerPrize = ""
for i in range(len(winnerEmail)):

    # For every prize thats available, assign one email to it

    winnerEmailAddress = winnerEmail[i]

    # Assign an email from the list to a prize from the list

    if i < len(prizeArray):

        winnerPrize = prizeArray[i]

        prizeArray.remove(winnerPrize)

        # Write array content to prize file, essentially removing used prizes

        openFile.close()  # Should delete all content

        writeToFile = open(prizeFile, 'w')

        writeToFile.write(prizeArray[i])  # Should write remaining prizes back to file





    else:

        print("No prize available for " + winnerEmail[i])

    # print(winnerEmailAddress, " won ", winnerPrize)

    # also need to remove this entry from prize file

    emailUserWithPrize(winnerEmailAddress, winnerPrize)

Answer 1

You would typically use the zip function for stuff like this. For example:

import re
import random
p = re.compile(r'^\w+@\w+\.\w+$')

prizes = ['blender', 'car', 'pencils', 'tablet']
emails = ['', 'sjadhgf', 'bob@bob.com', 'jack@bob.com',
          'jenny@bob.com', 'frank@google.com', 'someone@gmail.com',
          'other@other.com', 'runner@xxx.co']

valid_emails = [e for e in emails if p.match(e)]
random.shuffle(valid_emails)

for winner, prize in zip(valid_emails, prizes):
    print(f'{prize} goes to {winner}')

Answer 2

That is expected behaviour, since the check

if len(prizeList) > len(emailList):

Checks whether the prizelist is larger than the email list. This if statement has no else statement and thus the script stops when len(prizelist) <= len(emailList)

Whoever wrote this, probably applied this check so that the assumption "there are enough prizes for everyone" can be made from that point on.