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Document the running-dinner concept, setup (uv + .env API key), CSV input
schema, how to run it (CLI and library), output format, a "what to tweak"
table mapping each knob to its file:line, the algorithm (group building,
rotation topology, annealing), testing (offline + opt-in e2e), limitations,
and development commands.
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# Tatami # Tatami
Tool for Arranging Tasty Appointments, Meetings & Invitations
**T**ool for **A**rranging **T**asty **A**ppointments, **M**eetings & **I**nvitations.
Tatami generates a **running dinner** masterplan. Given a list of participants with
home addresses, it forms small hosting groups, decides which groups cook which
course and who visits whom, and orders the whole evening to minimize travel time
(by bike, using the Google Maps Routes API), finishing at a shared after‑party.
- [What is a running dinner?](#what-is-a-running-dinner)
- [How Tatami builds the plan](#how-tatami-builds-the-plan)
- [Requirements](#requirements)
- [Setup](#setup)
- [Input: the participant CSV](#input-the-participant-csv)
- [Running it](#running-it)
- [Output format](#output-format)
- [What you can tweak](#what-you-can-tweak)
- [How the algorithm works](#how-the-algorithm-works)
- [Testing](#testing)
- [Limitations & scaling](#limitations--scaling)
- [Project layout](#project-layout)
- [Development](#development)
---
## What is a running dinner?
A running dinner is a social dinner event spread across many homes. Participants
are split into **hosting groups**. The evening has three courses — **starter,
main, dessert** — and each group cooks **exactly one** course in their own home.
For the other two courses they travel to other groups' homes as guests. The
tables are mixed for every course, so people meet many others over the night.
Everyone converges on a common **after‑party** location at the end.
Tatami arranges all of this and tries to keep the total cycling time low.
## How Tatami builds the plan
The pipeline (see the `__main__` block of `src/tatami/tatami_masterplan.py`):
1. **Load participants** from a tab‑separated CSV into `Participant` objects.
2. **Fetch travel times** — a full pairwise duration matrix between every
participant address plus the after‑party address, via the Google Routes API.
3. **Build the masterplan**:
- Rank participants by how convenient they are as hosts (kitchen‑size penalty
plus distance to the after‑party), then split into **hosts** (one per group)
and **semi‑hosts** (distributed into the host groups).
- Reduce the full matrix to a host‑to‑host matrix and bake in each host's
kitchen‑size penalty.
- Run **simulated annealing** to find a low‑travel‑time assignment of groups
to the dinner rotation.
- Assign each group a course and compute who hosts whom for each course.
4. **Return** two lists of plain dicts (groups and participants) ready for
serialization.
## Requirements
- **Python ≥ 3.13**
- **[uv](https://docs.astral.sh/uv/)** for dependency management
- A **Google Maps API key** with the **Routes API** enabled
(the new `routes.googleapis.com` `computeRouteMatrix` endpoint — *not* the
legacy Distance Matrix API).
## Setup
```bash
# 1. Install dependencies (creates the virtualenv from uv.lock)
uv sync
# 2. Provide your API key
cp .env.example .env
# then edit .env and set GOOGLE_MAPS_API_KEY=...
```
The key is read from `.env` automatically (via `python-dotenv`). `.env` is
gitignored, so your secret never gets committed. An already‑exported
`GOOGLE_MAPS_API_KEY` environment variable takes precedence over the file.
> The package raises at import time if no key is found, so `GOOGLE_MAPS_API_KEY`
> must be set (even to a dummy value) just to import `tatami.traveltimes`.
## Input: the participant CSV
A **tab‑separated** file (the default working file is `test-config.csv` in the
directory you run from) with these columns:
| Column | Type | Meaning |
|----------------|--------|----------------------------------------------------------------------|
| `name` | string | Participant / household name. |
| `address` | string | Full postal address — this is what the Routes API geocodes. |
| `phone` | string | Contact number (carried through to the output, not used in routing). |
| `kitchen_size` | number | `0–10`; a *suitability‑to‑host* proxy. Bigger = better kitchen. |
| `allergies` | string | Free text (carried through, not used in routing). |
Example (columns separated by **tabs**):
```
name address phone kitchen_size allergies
Alice Römerstr. 12, 76189 Karlsruhe 555-1234 8 none
Bob Gottesauerstr. 30, 76131 Karlsruhe 555-5678 7 peanuts
Charlie Hermann-Hesse-Str 50, 76189 Karlsruhe 555-8765 9 none
```
## Running it
```bash
uv run python -m tatami.tatami_masterplan
```
This reads `test-config.csv` from the current directory, calls the Routes API,
and prints the generated masterplan. The after‑party address and travel mode are
currently set in the `__main__` block of `tatami_masterplan.py` (see
[What you can tweak](#what-you-can-tweak)).
To use Tatami from your own code:
```python
from tatami.tatami_masterplan import (
get_after_party_group, get_masterplan, load_csv_to_participants,
)
from tatami.traveltimes import get_participant_distance_matrix
participants = load_csv_to_participants("my-participants.csv")
after_party = get_after_party_group("Some Street 1, 12345 City")
distance_matrix = get_participant_distance_matrix(
[*participants, after_party.main_member], mode="BICYCLE"
)
groups, participants_out = get_masterplan(participants, distance_matrix, after_party)
```
## Output format
`get_masterplan` returns a tuple `(group_dicts, participant_dicts)`.
Each **group** dict:
```python
{
"uuid": "Group_…", # group id
"members": ["…", "…"], # participant uuids in this group
"main_member": "…", # the participant whose home is used for routing
"course": "starter", # "starter" | "main" | "dessert"
"hosts": ["…", "…", "…"], # the three groups this group eats with,
# ordered starter → main → dessert
# (includes this group itself, for its own course)
}
```
Each **participant** dict mirrors the CSV columns plus a `uuid`. Everything is
keyed by UUID, so resolve names/addresses by looking participants up by `uuid`.
> Note: only a group's `main_member` address is used for all travel calculations;
> other members are assumed to join at the main member's home.
## What you can tweak
All knobs currently live in the source. The most useful ones:
| What | Where | Default | Effect |
|------|-------|---------|--------|
| **After‑party address** | `tatami_masterplan.py:230` (`__main__`) | a Karlsruhe address | Where everyone ends the night; also influences host ranking. |
| **Travel mode** | `tatami_masterplan.py:233` (`mode="BICYCLE"`) | `BICYCLE` | Any Routes API `travelMode`: `BICYCLE`, `DRIVE`, `WALK`, `TWO_WHEELER`, `TRANSIT`. |
| **Group sizing** | `tatami_masterplan.py:24` (`len(participants) / 6`) | 1 group per ~6 people | The divisor sets how many participants form one "course‑triple". Larger → fewer, bigger groups. |
| **Kitchen‑size penalty** | `classes.py:19` (`minutes=3 * (10 - kitchen_size)`) | 3 min per point | Travel‑time‑equivalent penalty for small kitchens. Raise the `3` to push hosting toward big kitchens. |
| **Annealing schedule** | `tatami_masterplan.py:48–50` | `T=1000`, `cooling=0.99`, `iters=10000` | Optimization quality vs. runtime. More iterations / slower cooling → better routes, slower. |
| **Course names** | `tatami_masterplan.py:31` | `["starter", "main", "dessert"]` | The three courses. The 3‑course rotation is baked into the topology — changing the *count* needs more work (see below). |
| **Rotation topology** | `tatami_masterplan.py:172–173` (offsets `+1`, `-4`) | — | Defines who hosts whom. Changing these changes who meets whom; keep the invariant that each group's three hosts cover all three courses. |
| **Distance vs. duration** | `traveltimes.py` `get_distance_matrix(value=…)` | `"duration"` | Optimize on travel **time** (`"duration"`) or **distance** (`"distanceMeters"`). |
After changing routing‑relevant knobs, run the test suite (`uv run pytest`) — the
topology and cost invariants are covered there.
## How the algorithm works
### Group building
`groups_per_course = floor(n / 6)` groups are created **per course**, for
`3 × groups_per_course` groups total. Participants are sorted by
`get_after_party_time` (kitchen penalty + distance to after‑party); the best
become the one **host** of each group, and the rest are shuffled in round‑robin
as **semi‑hosts**. A group's `main_member` (the host) is the only address used
for that group in all distance lookups.
### Rotation topology (`get_courses`)
Each group occupies a **slot** `0 … n‑1`. The course a slot cooks is `slot % 3`
(`0 → starter`, `1 → main`, `2 → dessert`). For slot `i`, the three groups it
dines with are slots `i` (itself, for its own course), `i + 1`, and `i − 4`
(mod `n`). These offsets are chosen so that:
- a group's three hosts always cover **all three** courses,
- **every** host serves **exactly three** groups (itself + two guests) for its
course,
- guests are mixed differently at each course.
These invariants are verified in `tests/test_routing.py`.
### Route optimization (simulated annealing)
The decision variable is *which physical group sits in which slot*. For a given
assignment, `fast_total_time` sums every group's route
(starter‑host → main‑host → dessert‑host → after‑party) using the reduced,
penalty‑baked matrix. `simulated_annealing` starts from a random assignment and
repeatedly proposes swapping two slots, accepting worse solutions with Boltzmann
probability `exp(-Δ / T)` while the temperature `T` cools, and returns the best
assignment it finds. It is a **heuristic** — good, not provably optimal — though
on small instances it reliably reaches the true optimum.
## Testing
```bash
uv run pytest # full offline suite (no API calls, HTTP is mocked)
uv run pytest -m e2e # opt-in live test that calls the real Routes API
```
- The default suite (`tests/`) covers the domain model, group building, the
rotation topology, the route cost/optimization, and the Routes API wrapper
(with the HTTP layer mocked) — **no network, no API quota used**.
- `tests/test_e2e_api.py` is marked `e2e` and **excluded by default**. Run it
explicitly with `-m e2e`. It makes a single minimal request (two addresses →
a 2×2, 4‑element matrix) and **skips itself** if only a placeholder/dummy key
is available, so it never spuriously fails.
## Limitations & scaling
- **Participant count.** The Routes API `computeRouteMatrix` caps at **625
elements** (a 25×25 matrix), so Tatami currently handles up to ~**24
participants** plus the after‑party in one shot. Bigger events need batching.
- **Group counts** are multiples of 3, and you need **≥ 6 participants** before
any groups are formed at all.
- **Heuristic routing.** Simulated annealing does not guarantee the global
optimum on large instances; tune the schedule if results look poor.
- **One address per group.** Only the host's (`main_member`'s) address is used
for routing; guests are assumed to gather there.
## Project layout
```
src/tatami/
classes.py # Participant and Group domain model
traveltimes.py # Google Routes API wrapper + matrix helpers
tatami_masterplan.py # pipeline: load → fetch → group → optimize → assign
tests/ # pytest suite (offline + opt-in live e2e)
running_dinner/ # legacy standalone prototype — NOT used by the package
```
> `running_dinner/running_dinner.py` is a pre‑package prototype kept for
> reference only. It uses German field names, a brute‑force search, and the
> **legacy** Distance Matrix API. Don't assume its conventions apply to
> `src/tatami/`.
## Development
This project uses `uv` and enforces quality with `ruff` and `mypy`.
```bash
uv sync # install (incl. dev tools)
uv run ruff check # lint
uv run ruff format # format
uv run mypy --allow-redefinition src/ # type-check
uv run pre-commit install # enable the pre-commit hooks
```
Pre‑commit runs `ruff check`, `ruff format`, and `mypy` automatically (see
`.pre-commit-config.yaml`).