Got a total of who payed what and need to break it down to see who owes who? Use me!

rent_split.py

# Raymond Ho
# May 5, 2015

# Note: Run me through the terminal. 
# Sublime Text 2 won't successfully build b/c of Unicode errors.

import csv
import sys


def parseData(data, colPrice=1, colPerson=5, nameA='Alice', nameB='Bob'):

	'''
	data = A list containing the CSV data
	colPrice = The column that the prices are stored in
	colPerson = The column that stores who payed
	nameA = The name of person A
	nameB = The name of person B

	This function will calculate how much personA owes personB or vice versa.
	'''

	personA, personB = [], []
	totalA, totalB = 0, 0

	for entry in data:
		try:
			if entry[colPerson] == nameA:
				personA.append(entry)
				totalA += float(entry[colPrice])
			elif entry[colPerson] == nameB:
				personB.append(entry)
				totalB += float(entry[colPrice])
			else:
				print('Name not recognized: ' + entry[colPerson])
				# return

		except IndexError: # Blank line.
			continue

	difference = (totalA - totalB) / 2
	if totalA > totalB:
		print (("%s owes %s %.2f dollars.") % (nameB, nameA, difference))
	else:
		print (("%s owes %s %.2f dollars.") % (nameA, nameB, -difference))


def main():

	data = []
	with open(sys.argv[1]) as csvfile:
		expenses = csv.reader(csvfile)

		for row in expenses:
			data.append(row)
	
	parseData(data)

if __name__ == '__main__':
	if len(sys.argv) == 2:
		main()
	else:
		print("Please specify a .csv file.")

sample.csv

sample.output

Alice owes Bob 535.80 dollars.