build it all basically

README.md

@@ -1,2 +1,36 @@
 # wowhmm
-Who owes whom how much money?
+
+Who owes [whom](https://en.wiktionary.org/wiki/whom#Usage_notes) how much money?
+
+![wowhmm](https://github.com/yoonthegoon/wowhmm/media/wowhmm.png)
+
+## Installation
+
+<!-- TODO: Set this up with PyPI. -->
+
+```bash
+pip install wowhmm
+```
+
+## Usage
+
+```python
+>>> from wowhmm import Ledger
+>>>
+>>> ledger = Ledger(
+...     [
+...         ("Alice", 349.95, ["Alice", "Bob", "Carol", "Dan"]),  # BnB
+...         ("Bob", 68.42, ["Alice", "Dan"]),  # Alcohol
+...         ("Bob", 42.02, ["Alice", "Bob", "Carol", "Dan"]),  # Groceries
+...         ("Dan", 72.48, ["Alice", "Bob", "Carol", "Dan"]),  # Transportation
+...         ("Carol", 28.98, ["Carol", "Dan"]),  # Movies
+...     ]
+... )
+>>>
+>>> ledger.tabulate()
+       Alice    Bob  Carol    Dan
+Alice   0.00 -42.77 -87.49 -69.37
+Bob    42.77   0.00 -10.51 -26.60
+Carol  87.49  10.51   0.00   3.63
+Dan    69.37  26.60  -3.63   0.00
+```

requirements.txt

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+pandas==2.2.2

setup.py

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+from setuptools import find_packages, setup
+
+with open("README.md", "r") as f:
+    long_description = f.read()
+
+setup(
+    name="wowhmm",
+    version="0.1.4",
+    description="Who owes whom how much money",
+    long_description=long_description,
+    long_description_content_type="text/markdown",
+    url="https://github.com/yoonthegoon/wowhmm",
+    packages=find_packages(),
+    install_requires=[
+        "pandas==2.2.2",
+    ],
+)

wowhmm/__init__.py

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+from .core import Ledger

wowhmm/core.py

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+from typing import List, NamedTuple
+
+import pandas as pd
+
+
+class Spent(NamedTuple):
+    """
+    Who spent amount for whom.
+
+    :param who: The person who spent the money
+    :param amount: The amount of money spent
+    :param for_whom: The people for whom the money was spent
+    """
+
+    who: str
+    amount: float
+    for_whom: List[str]
+
+
+class Ledger:
+    def __init__(self, transactions: List[Spent] = None):
+        """
+        A ledger of transactions.
+
+        :param transactions: A list of transactions
+        """
+
+        self.transactions = transactions or []
+        if not all(isinstance(transaction, Spent) for transaction in self.transactions):
+            self.transactions = [
+                Spent(who, amount, for_whom) for who, amount, for_whom in transactions
+            ]
+
+    def tabulate(self) -> pd.DataFrame:
+        """
+        Tabulate who owes whom how much.
+        Values are negative if the person owes money and positive if the person is owed money.
+        Values are rounded to two decimal places.
+
+        :return: A DataFrame of who owes whom how much
+        """
+
+        names = set(
+            name for transaction in self.transactions for name in transaction[2]
+        )
+        names.update(transaction[0] for transaction in self.transactions)
+        names = sorted(names)
+
+        df = pd.DataFrame(0.0, index=names, columns=names)
+
+        for payer, amount, payees in self.transactions:
+            for payee in payees:
+                if payer != payee:
+                    value = round(amount / len(payees), 2)
+                    df.loc[payer, payee] -= value
+                    df.loc[payee, payer] += value
+
+        return df