rusket 0.1.9

Blazing-fast FP-Growth and Association Rules — pure Rust via PyO3

rusket

Blazing-fast FP-Growth and Association Rules for Python, powered by Rust.

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rusket is a drop-in replacement for mlxtend's fpgrowth and association_rules — backed by a Rust core (via PyO3) that delivers 5–10× speed-ups and dramatically lower memory usage. It natively supports Pandas (including the Arrow backend introduced in pandas 2.0), Polars, and sparse DataFrames out of the box.

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✨ Highlights

	rusket	mlxtend
Core language	Rust (PyO3)	Pure Python
Pandas dense input	✅ C-contiguous np.uint8	✅
Pandas Arrow backend	✅ Arrow zero-copy (pandas 2.0+)	❌ Not supported
Pandas sparse input	✅ Zero-copy CSR → Rust	❌ Densifies first
Polars input	✅ Arrow zero-copy	❌ Not supported
Parallel mining	✅ Rayon work-stealing	❌ Single-threaded
Memory	Low (native Rust buffers)	High (Python objects)
API compatibility	✅ Drop-in replacement	—
Metrics	12 built-in metrics	9

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📦 Installation

pip install rusket
# or with uv:
uv add rusket

Optional extras:

# Polars support
pip install "rusket[polars]"

# Pandas/NumPy support (usually already installed)
pip install "rusket[pandas]"

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🚀 Quick Start

Basic — Pandas

import pandas as pd
from rusket import fpgrowth, association_rules

# One-hot encoded boolean DataFrame
data = {
    "bread":  [1, 1, 0, 1, 1],
    "butter": [1, 0, 1, 1, 0],
    "milk":   [1, 1, 1, 0, 1],
    "eggs":   [0, 1, 1, 0, 1],
    "cheese": [0, 0, 1, 0, 0],
}
df = pd.DataFrame(data).astype(bool)

# 1. Mine frequent itemsets
freq = fpgrowth(df, min_support=0.4, use_colnames=True)

# 2. Generate association rules
rules = association_rules(
    freq,
    num_itemsets=len(df),
    metric="confidence",
    min_threshold=0.6,
)

print(rules[["antecedents", "consequents", "support", "confidence", "lift"]]
      .sort_values("lift", ascending=False))

Output looks exactly like mlxtend:

     antecedents    consequents  support  confidence   lift
 (bread, butter)       (milk,)     0.07        0.92   2.41
        (milk,)  (bread, eggs)     0.06        0.78   1.89

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🐻‍❄️ Polars Input

rusket natively accepts Polars DataFrames. Data is transferred via Arrow zero-copy buffers — no conversion overhead.

import polars as pl
import numpy as np
from rusket import fpgrowth, association_rules

# ── 1. Create a Polars DataFrame ────────────────────────────────────
rng = np.random.default_rng(0)
n_rows, n_cols = 20_000, 150
products = [f"product_{i:03d}" for i in range(n_cols)]

# Power-law popularity: top products appear often, tail products are rare
support = np.clip(0.5 / np.arange(1, n_cols + 1, dtype=float) ** 0.5, 0.005, 0.5)
matrix = rng.random((n_rows, n_cols)) < support

df_pl = pl.DataFrame({p: matrix[:, i].tolist() for i, p in enumerate(products)})
print(f"Polars DataFrame: {df_pl.shape[0]:,} rows × {df_pl.shape[1]} columns")

# ── 2. fpgrowth — same API as pandas ────────────────────────────────
freq = fpgrowth(df_pl, min_support=0.05, use_colnames=True)
print(f"Frequent itemsets: {len(freq):,}")
print(freq.sort_values("support", ascending=False).head(8))

# ── 3. Association rules ────────────────────────────────────────────
rules = association_rules(freq, num_itemsets=n_rows, metric="lift", min_threshold=1.1)
print(f"Rules: {len(rules):,}")
print(
    rules[["antecedents", "consequents", "confidence", "lift"]]
    .sort_values("lift", ascending=False)
    .head(6)
)

Or more concisely — just read a Parquet file:

import polars as pl
from rusket import fpgrowth

df = pl.read_parquet("transactions.parquet")
freq = fpgrowth(df, min_support=0.05, use_colnames=True)

How it works under the hood:
Polars → Arrow buffer → np.uint8 (zero-copy) → Rust fpgrowth_from_dense

---

📊 Sparse Pandas Input

For very sparse datasets (e.g. e-commerce with thousands of SKUs), use Pandas SparseDtype to minimize memory. rusket passes the raw CSR arrays straight to Rust — no densification ever happens.

import pandas as pd
import numpy as np
from rusket import fpgrowth

rng = np.random.default_rng(7)
n_rows, n_cols = 30_000, 500

# Very sparse: average basket size ≈ 3 items out of 500
p_buy = 3 / n_cols
matrix = rng.random((n_rows, n_cols)) < p_buy
products = [f"sku_{i:04d}" for i in range(n_cols)]

df_dense = pd.DataFrame(matrix.astype(bool), columns=products)
df_sparse = df_dense.astype(pd.SparseDtype("bool", fill_value=False))

dense_mb = df_dense.memory_usage(deep=True).sum() / 1e6
sparse_mb = df_sparse.memory_usage(deep=True).sum() / 1e6
print(f"Dense  memory: {dense_mb:.1f} MB")
print(f"Sparse memory: {sparse_mb:.1f} MB  ({dense_mb / sparse_mb:.1f}× smaller)")

# Same API, same results — just faster and lighter
freq = fpgrowth(df_sparse, min_support=0.01, use_colnames=True)
print(f"Frequent itemsets: {len(freq):,}")

How it works under the hood:
Sparse DataFrame → COO → CSR → (indptr, indices) → Rust fpgrowth_from_csr

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🔄 Migrating from mlxtend

rusket is a drop-in replacement. The only API difference is num_itemsets:

- from mlxtend.frequent_patterns import fpgrowth, association_rules
+ from rusket import fpgrowth, association_rules

  freq  = fpgrowth(df, min_support=0.05, use_colnames=True)        # identical

- rules = association_rules(freq, metric="lift", min_threshold=1.2)
+ rules = association_rules(freq, num_itemsets=len(df),             # ← add this
+                           metric="lift", min_threshold=1.2)

Why num_itemsets? This makes support calculation explicit and avoids a hidden internal pandas join that mlxtend performs.

Gotchas:

1. Input must be bool or 0/1 integers — rusket warns if you pass floats
2. Polars is supported natively — just pass the DataFrame directly
3. Sparse pandas DataFrames work too — and use much less RAM

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📖 API Reference

fpgrowth

rusket.fpgrowth(
    df,
    min_support: float = 0.5,
    null_values: bool = False,
    use_colnames: bool = False,
    max_len: int | None = None,
    verbose: int = 0,
) -> pd.DataFrame

Parameter	Type	Description
df	pd.DataFrame | pl.DataFrame | np.ndarray	One-hot encoded input (bool / 0-1). Dense, sparse, or Polars.
min_support	float	Minimum support threshold in (0, 1].
null_values	bool	Allow NaN values in df (pandas only).
use_colnames	bool	Return column names instead of integer indices in itemsets.
max_len	int | None	Maximum itemset length. None = unlimited.
verbose	int	Verbosity level (kept for API compatibility with mlxtend).

Returns a pd.DataFrame with columns ['support', 'itemsets'].
Each itemset is a frozenset of column indices (or names when use_colnames=True).

---

association_rules

rusket.association_rules(
    df,
    num_itemsets: int,
    metric: str = "confidence",
    min_threshold: float = 0.8,
    support_only: bool = False,
    return_metrics: list[str] = [...],  # all 12 metrics by default
) -> pd.DataFrame

Parameter	Type	Description
df	pd.DataFrame	Output from fpgrowth().
num_itemsets	int	Number of transactions in the original dataset (len(df_original)).
metric	str	Metric to filter rules on (see table below).
min_threshold	float	Minimum value of metric to include a rule.
support_only	bool	Only compute support; fill other columns with NaN.
return_metrics	list[str]	Subset of metrics to include in the result.

Returns a pd.DataFrame with columns antecedents, consequents, plus all requested metric columns.

Available Metrics

Metric	Formula / Description
support	P(A ∪ B)
confidence	P(B | A)
lift	confidence / P(B)
leverage	support − P(A)·P(B)
conviction	(1 − P(B)) / (1 − confidence)
zhangs_metric	Symmetrical correlation measure
jaccard	Jaccard similarity between A and B
certainty	Certainty factor
kulczynski	Average of P(B|A) and P(A|B)
representativity	Rule coverage across transactions
antecedent support	P(A)
consequent support	P(B)

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⚡ Benchmarks

Measured on Apple M-series (arm64). mlxtend 0.23, rusket 0.1. Numbers from an actual run — synthetic market-basket data (Faker, power-law popularity).

Dataset	rusket (pandas)	rusket (polars)	mlxtend	Speedup
small — 1 k × 50 items	0.007 s	0.006 s	0.166 s	24×
medium — 10 k × 400 items	0.555 s	0.244 s	8.335 s	15×
large — 100 k × 1 000 items	0.572 s	0.819 s	18.652 s	33×
HUGE — 1 M × 2 000 items	3.113 s	6.015 s	104.024 s	33×

Memory usage at large scale matches the input matrix size — Rust buffers add virtually zero overhead. See the full interactive benchmark report for charts and memory breakdown.

Run benchmarks yourself:

# pytest-benchmark suite
uv run pytest tests/test_benchmark.py -v -s

# Full interactive Plotly report (rusket vs mlxtend vs polars)
uv run python tests/generate_benchmark_report.py

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🏗 Architecture

Data Flow

pandas dense         ──► np.uint8 array (C-contiguous)  ──► Rust fpgrowth_from_dense
pandas Arrow backend ──► Arrow → np.uint8 (zero-copy)   ──► Rust fpgrowth_from_dense
pandas sparse        ──► CSR int32 arrays               ──► Rust fpgrowth_from_csr
polars               ──► Arrow → np.uint8 (zero-copy)   ──► Rust fpgrowth_from_dense
numpy ndarray        ──► np.uint8 (C-contiguous)        ──► Rust fpgrowth_from_dense

All mining and rule generation happens inside Rust. No Python loops, no round-trips.

Project Structure

rusket/
├── src/                          # Rust core (PyO3)
│   ├── lib.rs                    # Module root & Python bindings
│   ├── fpgrowth.rs               # FP-Tree construction + FP-Growth mining
│   └── association_rules.rs      # Rule generation + 12 metrics (Rayon parallel)
│
├── rusket/                       # Python wrappers & validation
│   ├── __init__.py               # Package root
│   ├── fpgrowth.py               # Input dispatch (dense / sparse / Polars / ndarray)
│   ├── association_rules.py      # Label mapping + Rust call + result assembly
│   ├── _validation.py            # Input validation
│   └── _rusket.pyi               # Type stubs for Rust extension
│
├── tests/                        # Comprehensive test suite
├── examples/                     # Runnable example scripts
├── docs/                         # MkDocs documentation
└── pyproject.toml                # Build config (maturin)

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🧑‍💻 Development

Prerequisites

• Rust 1.83+ (rustup update)
• Python 3.10+
• uv (recommended package manager)

Getting Started

# Clone
git clone https://github.com/bmsuisse/rusket.git
cd rusket

# Build Rust extension in dev mode
uv run maturin develop --release

# Run the full test suite
uv run pytest tests/ -x -q

# Type-check the Python layer
uv run pyright rusket/

# Cargo check (Rust)
cargo check

Run Examples

# Getting started
uv run python examples/01_getting_started.py

# Market basket analysis with Faker
uv run python examples/02_market_basket_faker.py

# Polars input
uv run python examples/03_polars_input.py

# Sparse input
uv run python examples/04_sparse_input.py

# Large-scale mining (100k+ rows)
uv run python examples/05_large_scale.py

# mlxtend migration guide
uv run python examples/06_mlxtend_migration.py

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📜 License

BSD 3-Clause