Arena-Rank: The ranking methodology powering the Arena leaderboard.

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Installation

From pip: pip install arena-rank

From source:

git clone https://github.com/lmarena/arena-rank && cd arena-rank
uv sync

Examples

Running the examples

1. Clone the repository and install dependencies using your preferred package manager (e.g. uv sync, pip install arena-rank)
2. Open any notebook in examples/ using your preferred tool (e.g. VS Code, Cursor, Jupyter)
3. Select the project's virtual environment (e.g. .venv/) as your kernel when prompted, then run all cells

Below is a minimal example using Arena-Rank to produce a leaderboard on Arena data:

import pandas as pd
import datasets
from arena_rank.utils.data_utils import PairDataset
from arena_rank.models.bradley_terry import BradleyTerry

df = datasets.load_dataset(
    "lmarena-ai/arena-human-preference-140k",
    columns=["model_a", "model_b", "winner"]
)["train"].to_pandas()

dataset = PairDataset.from_pandas(df)
model = BradleyTerry(n_competitors=len(dataset.competitors))

# compute ratings and 95% confidence intervals
results = model.compute_ratings_and_cis(dataset, significance_level=0.05)

# print top 10 competitors with ratings and confidence intervals
leaderboard = pd.DataFrame(results).sort_values("ratings", ascending=False).head(10)
print(leaderboard.to_markdown(index=False))

| competitors                         |   ratings |   rating_lower |   rating_upper |   variances |
|:------------------------------------|----------:|---------------:|---------------:|------------:|
| gemini-2.5-pro                      |   1124.07 |        1117.61 |        1130.53 |    10.8542  |
| gemini-2.5-pro-preview-03-25        |   1097.88 |        1082    |        1113.77 |    65.6717  |
| grok-4-0709                         |   1093.34 |        1078.44 |        1108.25 |    57.8409  |
| o3-2025-04-16                       |   1079.39 |        1072.86 |        1085.92 |    11.0919  |
| chatgpt-4o-latest-20250326          |   1078.14 |        1071.33 |        1084.94 |    12.0447  |
| gemini-2.5-pro-preview-05-06        |   1074.8  |        1064.55 |        1085.05 |    27.3722  |
| deepseek-r1-0528                    |   1074.48 |        1067.19 |        1081.78 |    13.8388  |
| grok-3-preview-02-24                |   1071.28 |        1063.7  |        1078.85 |    14.9286  |
| llama-4-maverick-03-26-experimental |   1067.21 |        1059.38 |        1075.04 |    15.953   |
| gemini-2.5-flash                    |   1061.26 |        1055.31 |        1067.22 |    9.21695  |

See the examples folder for notebooks with more advanced examples, covering techniques such as the style-controlled leaderboard on Arena, analysis of voter patterns on the PRISM dataset, and analysis of sports and video game competitions using the Bradley-Terry methodology.

Contributing

We welcome and encourage contributions. To develop Arena-Rank, make sure to install the development dependencies and the git pre-commit hooks.

uv sync --group dev
pre-commit install