abcFinance (short for 'agent-based computational Finance') provides tools for using standard double-entry bookkeeping methods either directly or within an agent-based modelling framework. It is a sister library to the abcEconomics (agent-based computational Economics) library.

The Ledger class implements an accounting system. Booking statements are recorded through the book() method. The basic syntax works as follows:

accountingsystem = Ledger()
accountingsystem.make_stock_accounts('Assets', 'Liabilities')
accountingsystem.book(debit=[('Assets',100)], credit=[('Liabilities',100)]

where debit and credit are lists of tuples ('account', amount) of accounts that should be booked by amount on the debit and credit side, respectively. The total sum of debits and credits needs to be equal in one booking statement. Accounts have to be declared as either stock or flow accounts before they can be booked.

The balance sheet is composed of all stock accounts and includes an equity account whose name can be set using the optional residual_account_name flag in the constructor of Ledger. The profit and loss statement is composed of all flow accounts. It can be viewed using the print_profit_and_loss() statement. The profit or loss for the period can be booked against equity using the book_end_of_period() method, which also resets all flow accounts. The balance sheet can be printed using the print_balance_sheet() method. draw_balance_sheet() returns the string representation of an SVG image of the balance sheet. Several other helpful methods are available.

Extensive examples can be found in the examples\money_creation folder.

The Ledger class can be used as an attribute for an Agent class in an agent-based modelling system, enabling the use of financial accounting within agent-based models. One implementation is provided in the form of the AbcFinanceAgent class, which inherits from the Agent class in the abcEconomics library. abcEconomics is designed to be compatible with abcFinance and provides several methods to facilitate the use of abcFinance methods in agent-based models. The accounting system provided in abcFinance can in principle be used with any agent-based modelling system.