Mahlzeit food accounting

You're buying groceries and cooking food for and share them with friends or colleagues. Next time, a different colleague buys and cooks food. In between, a bank note changes hands. Who owes how much money after a week's (or more) worth of buying, cooking and eating?

In order to track the balances of all participants, all transactions (purchases as well as cash exchanging hands or bank accounts) need to be accounted using the Mahlzeit class and Mahlzeit.einkauf() and Mahlzeit.bezahlung() methods.

For viewing the balances (and transaction), the following methods exist:

• As python dict via Mahlzeit.calc() with a simple mapping of the overall account balance: [account]balance
• Sorted and formatted directly on the console via Mahlzeit.pretty(file=sys.stdout)
• In a ledger-compatible format (which requires dates and descriptions to be set for each transaction) via Mahlzeit.ledger(file=sys.stdout, prec=3)

API and usage

Transactions are grouped within a Mahlzeit object:

from Mahlzeit import Mahlzeit
m = Mahlzeit()

Each purchase is recorded as call to Mahlzeit.einkauf(amount, eaters, payer, datum=None, description=None, comment=None):

m.einkauf(10, ('Alice', 'Bob'), 'Alice')

eaters and payer may be a single string, tuple or list or strings or Esser objects.

Change in cash can be recorded with a call to Mahlzeit.bezahlung(payer, payee, amount, datum=None, description=None, comment=None):

m.bezahlung('Bob', 'Alice', 5)

If ledger-compatible output is desired, each transaction (einkauf and bezahlung) must be annotated with a date and description:

m.einkauf(10, ('Alice', 'Bob'), 'Alice', datum='2022/03/16', description='Kebap')
m.bezahlung('Bob', 'Alice', 5, datum='2022/03/17', description='Payback')

Which can be used in a context to group several transactions within the same annotation:

with m(datum='2022/03/16', description='Kebap'):
    m.einkauf(10, ('Alice', 'Bob'), 'Alice')
    m.bezahlung('Bob', 'Alice', 5)

Quick console output:

m.pretty()

Or ledger output:

m.journal()

to be interactively used as

hledger -f <(python3 main.py) balance

We feature a convenience wrapper for "weighing" eaters. In some cases you need to weigh eaters in case the is a couple at the weight of 2 or 0.5. Instantiate a object of class Esser(name: str, weight: float):

from mahlzeit import Mahlzeit, Esser as E
m = Mahlzeit()
m.einkauf(15, ('Laura', 'Nils', E('Katja_Martin', 2), 'Max'), 'Katja_Martin')
m.pprint()

Example integration into a personal ledger (ref. plaintextaccounting)

This example explains how to integrate the --ledger output of the Mahlzeit module into your personal journal. It assumes that you're translating the Mahlzeit account for eating $you:einkauf:esser to your personal expense account e.g. expenses:food:work. Account money you spend for you and your colleagues as liabilities:kollegen.

.PHONY: auto-mahlzeit.journal

auto-mahlzeit.journal:
	hledger -f <(echo -e "= expenses:food:work\n    unused    *1\n    liabilities:kollegen  *-1\n"; MAHLZEIT_PLACES=2 venv/bin/python main.py --ledger) \
	--alias=meschenbacher:einkauf:esser=expenses:food:work \
	--alias=/meschenbacher:bezahlung:bezahlt*er/=unused \
	--alias=/meschenbacher:einkauf:bezahler/=unused \
	--alias=/.*:\(einkauf\|bezahlung\):.*/=unused \
	--begin 2022-04-09 \
	print --auto > $@

and include it into your journal via include.

Installation

Via pip

pip install mahlzeit