script used to calculate per person expenses from our Japan trip

expenses.py

import csv

CONVERSION_RATE = 117.3

class Trans:
    def __init__(self, item, receiver, giver, amount):
        self.item = item
        self.receiver = receiver
        self.giver = giver
        self.amount = amount

people = ["eric", "adam", "vincent", "kristian", "todd", "nathan", "sandy", "jon"]
transactions = []
giveTransactions = {}

#process and add transactions
with open('expenses.csv', 'r') as f:
    reader = csv.reader(f)
    for row in reader:
        item = row[0]
        cost = row[1]
        currency = row[2]
        paidby = row[3].lower()
        paidfor = row[4].lower()
        processed = False

        if currency.lower() == 'usd':
            cost = float(cost) * CONVERSION_RATE

        if(paidby == paidfor):
            continue

        if(paidfor == 'everyone'):
            cost = float(cost) / len(people)

            for giver in people:
                if giver == paidby:
                    continue

                transactions.append(Trans(item, paidby, giver, cost))

                processed = True
        elif ' ' in paidfor:
            names = paidfor.strip().split(' ')
            cost = float(cost) / len(names)
            for giver in names:
                if giver.lower() == paidby:
                    continue

                transactions.append(Trans(item, paidby, giver, cost))
                processed = True
        else:
            if not paidfor in people or not paidby in people:
                continue

            transactions.append(Trans(item, paidby, paidfor, cost))
            processed = True

        if not processed and paidby != "":
            print(row)
            print("not processed error")


# calculate totals per person
totals = {}
details = {}

for person in people:
    totals[person] = 0
    details[person] = []

for trans in transactions:
    totals[trans.receiver] = totals[trans.receiver] + float(trans.amount)
    details[trans.receiver].append((float(trans.amount), trans.item))
    totals[trans.giver] = totals[trans.giver] - float(trans.amount)
    details[trans.giver].append((float(trans.amount) * -1, trans.item))

# calculate venmo transactions
transferTransactions = {}
givers = []
receivers = []

for person in people:
    transferTransactions[person] = []

for person in people:
    if totals[person] > 0:
        receivers.append((person, totals[person]))
    else:
        givers.append((person, totals[person]))

for giver in givers:
    giveBalance = giver[1] * -1

    while giveBalance > 0.0000001:
        receiver = receivers.pop()
        receiveBalance = receiver[1]

        if giveBalance > receiveBalance:
            transferTransactions[receiver[0]].append((giver[0], receiveBalance))
            transferTransactions[giver[0]].append((receiver[0], receiveBalance * -1))
            giveBalance = giveBalance - receiveBalance
            receiveBalance = 0
        else:
            transferTransactions[receiver[0]].append((giver[0], giveBalance))
            transferTransactions[giver[0]].append((receiver[0], giveBalance * -1))
            receiveBalance = receiveBalance - giveBalance
            giveBalance = 0
            receivers.append((receiver[0], receiveBalance))

# print results
for person in people:
    f = open(person + '_expenses.txt', 'w')
    f.write("Total: " + str(totals[person]) + '\n')
    f.write("Total: $" + str(totals[person] / CONVERSION_RATE) + ' USD\n')

    f.write("\n*******Transfers*******\n\n")
    for trans in transferTransactions[person]:
        amount = trans[1] / CONVERSION_RATE

        if amount > 0:
            f.write("Receive $" + format(amount, '.2f') + " from " + trans[0] + '\n')
        else:
            f.write("Give $" + format(amount * -1, '.2f') + " to " + trans[0] + '\n')

    f.write("\n*******Transactions*******\n\n")
    for t in details[person]:
        f.write(str(t[0]) + '\t' + str(t[1]) + '\n')