OkCampKid

A band formation optimizer for Girls Rock! summer camp. Automatically assigns campers into balanced bands based on instrument preferences, age distribution, and bandmate compatibility.

Features

• Preference-aware matching: Campers specify who they want to play with and who they'd prefer to avoid
• Scalable algorithm: Handles 100-200 campers in seconds using greedy construction + local search
• Age-balanced bands: Scores bands higher when members are close in age
• Valid band constraints: Each band requires exactly 1 drummer, 1-2 guitarists, 1-2 bassists, optional keyboard player
• Persistent storage: Save and load camper lists between sessions

Installation

Requires Clojure and Leiningen.

lein deps

Usage

Start the interactive REPL:

lein run

Menu Options

1. Add a new camper — Enter name, age, instrument, and bandmate preferences (comma-separated)
2. View current campers — Display all loaded campers
3. Edit a camper — Remove and re-add a camper
4. Suggest band formations — Generate the optimal formation
5. Exit — Quit the program
6. Load test data — Load 16 sample campers for testing
7. Save campers to file — Persist camper list to disk (EDN format)
8. Load campers from file — Restore camper list from disk

Example Workflow

lein run
→ Menu appears
→ Select "6" to load test data
→ Select "4" to see suggested formations
→ Select "7" to save campers.edn

Algorithm

The band formation uses a two-phase optimization:

1. Greedy Construction:

   • Start one band per drummer
   • Assign each non-drummer to the band that maximizes their marginal score contribution
   • Respects instrument capacity constraints (1-2 guitarists, 1-2 bassists, 0+ keyboardists per band)

2. Local Search:

   • Repeatedly try swapping pairs of non-drummer campers between different bands
   • Accept swaps that improve the total formation score
   • Stop when no improvement is possible (local optimum)

Scoring

Each band's score combines:

• Age balance (0-10 points): Tighter age grouping scores higher

  • stddev ≤ 1.0 → 10 points
  • stddev ≤ 3.0 → 8 points
  • stddev ≤ 5.0 → 4 points
  • stddev ≤ 7.0 → 2 points
  • else → 1 point

• Preference matching (variable):

  • Mutual want (both want each other) → +3 per pair
  • One-way want → +1 per pair
  • Either camper avoids the other → -5 per pair

Data Format

Campers are stored as EDN (Clojure data format):

{:name "Alice"
 :age 12
 :instrument :drums
 :wants ["Bob" "Charlie"]
 :avoids ["Diana"]}

Valid instruments: :drums, :guitar, :bass, :keys

Testing

lein test

Future Enhancements

• Integration with Salesforce for camper import/export
• Web UI for band assignment visualization
• Multi-instrument support per camper
• Advanced constraint handling (skill levels, accessibility needs)

License

Copyright © 2017-2026

Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.