iouopt

iouopt simplifies group IOU settlement. If you've used Splitwise or similar apps, you're familiar with the concept.

Usage

import iouopt import Journal

j = Journal[str]()

j.append(borrower="A", lender="B", amount=5)
j.append("A", "C", 15)
j.append("B", "A", 10)
j.append("B", "C", 5)
j.append("C", "A", 20)
j.append("C", "B", 15)

for borrower, lender, amount in j.simplify():
    print(f"#=> {borrower} pays {lender} {amount}")

#=> C pays A 10
#=> C pays B 5

Note: iouopt requires that all amounts are represented as an int. This is a constraint of the underlying network simplex algorithm. If you need to express partial units, such as 15.78, multiply amounts by a suitable constant factor (e.g., 100) and then convert them to an int.