aprender

Next Generation Machine Learning, Statistics and Deep Learning in PURE Rust

Overview

Aprender is a lightweight, pure Rust machine learning library designed for efficiency and ease of use. Built with EXTREME TDD methodology, it provides reliable implementations of core ML algorithms with comprehensive test coverage.

Features

Core Primitives

• Vector - 1D numerical array with statistical operations (mean, sum, dot, norm, variance)
  • Powered by trueno v0.4.1 for SIMD acceleration
• Matrix - 2D numerical array with linear algebra (matmul, transpose, Cholesky decomposition)
  • SIMD-optimized operations via trueno backend
• DataFrame - Named column container for ML data preparation workflows

Supervised Learning (TOP 10 ML Algorithms ✅)

• LinearRegression - Ordinary Least Squares via normal equations
• LogisticRegression - Binary/multi-class classification with gradient descent
• DecisionTreeClassifier - GINI-based decision tree with configurable max depth
• RandomForestClassifier - Bootstrap aggregating ensemble with majority voting
• GradientBoostingClassifier - Adaptive boosting with residual learning
• NaiveBayes (GaussianNB) - Probabilistic classification with Bayes' theorem
• KNeighborsClassifier - Distance-based classification (k-NN)
• LinearSVM - Support Vector Machine with hinge loss and subgradient descent

Unsupervised Learning

• KMeans - K-means++ initialization with Lloyd's algorithm
• DBSCAN - Density-based clustering with eps and min_samples
• HierarchicalClustering - Agglomerative clustering with linkage methods
• GaussianMixture - EM algorithm for soft clustering
• SpectralClustering - Graph Laplacian eigendecomposition clustering
• IsolationForest - Ensemble-based anomaly detection
• LocalOutlierFactor - Density-based outlier detection
• PCA - Principal Component Analysis for dimensionality reduction (TOP 10 ✅)
• TSNE - t-SNE for non-linear visualization

Graph Algorithms

• Graph - Adjacency list representation with weighted/unweighted edges
• Betweenness Centrality - Shortest path-based node importance
• PageRank - Iterative power method for node ranking
• Louvain - Community detection via modularity optimization

Association Rule Mining

• Apriori - Frequent itemset mining for market basket analysis
• Support, confidence, and lift metrics

Descriptive Statistics

• Mean, Median, Mode, Variance, Standard Deviation
• Quartiles (Q1, Q2, Q3), Interquartile Range (IQR)
• Histograms with multiple binning strategies (Freedman-Diaconis, Sturges, Scott, Square Root)
• Five-number summary (min, Q1, median, Q3, max)

Model Selection & Evaluation

• train_test_split - Random train/test splitting with reproducible seeds
• KFold - K-fold cross-validator with optional shuffling
• cross_validate - Automated cross-validation with statistics (mean, std, min, max)

Model Persistence

• Serialization - Save/load models to disk (serde + bincode)
• Works with all models

Metrics

• Regression: r_squared, mse, rmse, mae
• Classification: accuracy, precision, recall, f1_score, confusion_matrix
• Clustering: silhouette_score, inertia

Installation

Add to your Cargo.toml:

[dependencies]
aprender = "0.4.1"

Quick Start

Linear Regression

use aprender::prelude::*;

fn main() {
    // Features: [sqft, bedrooms]
    let x = Matrix::from_vec(5, 2, vec![
        1500.0, 3.0,
        2000.0, 4.0,
        1200.0, 2.0,
        1800.0, 3.0,
        2500.0, 5.0,
    ]).unwrap();

    // Target: price
    let y = Vector::from_slice(&[250.0, 350.0, 180.0, 280.0, 450.0]);

    let mut model = LinearRegression::new();
    model.fit(&x, &y).expect("Failed to fit");

    let predictions = model.predict(&x);
    let r2 = model.score(&x, &y);

    println!("R² Score: {:.4}", r2);
}

K-Means Clustering

use aprender::prelude::*;

fn main() {
    let x = Matrix::from_vec(6, 2, vec![
        1.0, 2.0,
        1.5, 1.8,
        5.0, 8.0,
        6.0, 8.0,
        1.0, 0.6,
        9.0, 11.0,
    ]).unwrap();

    let mut kmeans = KMeans::new(2)
        .with_max_iter(100)
        .with_random_state(42);

    kmeans.fit(&x).expect("Failed to fit");

    let labels = kmeans.predict(&x);
    let score = silhouette_score(&x, &labels);

    println!("Silhouette Score: {:.4}", score);
}

Random Forest Classification

use aprender::prelude::*;
use aprender::tree::RandomForestClassifier;

fn main() {
    // Iris dataset (simplified)
    let x = Matrix::from_vec(12, 2, vec![
        1.4, 0.2, 1.3, 0.2, 1.5, 0.2, 1.7, 0.4,  // Setosa
        4.7, 1.4, 4.5, 1.5, 4.9, 1.5, 4.6, 1.3,  // Versicolor
        6.0, 2.5, 5.9, 2.1, 6.1, 2.3, 5.8, 2.2,  // Virginica
    ]).unwrap();
    let y = vec![0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2];

    let mut rf = RandomForestClassifier::new(20)
        .with_max_depth(5)
        .with_random_state(42);

    rf.fit(&x, &y).expect("Failed to fit");

    let predictions = rf.predict(&x);
    let accuracy = rf.score(&x, &y);

    println!("Accuracy: {:.1}%", accuracy * 100.0);
}

Cross-Validation

use aprender::prelude::*;
use aprender::model_selection::{cross_validate, KFold};

fn main() {
    let x = Matrix::from_vec(100, 1, (0..100).map(|i| i as f32).collect()).unwrap();
    let y = Vector::from_vec((0..100).map(|i| 2.0 * i as f32 + 1.0).collect());

    let model = LinearRegression::new();
    let kfold = KFold::new(10).with_random_state(42);

    let results = cross_validate(&model, &x, &y, &kfold).unwrap();

    println!("Mean R²: {:.4} ± {:.4}", results.mean(), results.std());
    println!("Min/Max: {:.4} / {:.4}", results.min(), results.max());
}

Examples

Run any of the 26+ included examples:

Supervised Learning

cargo run --example boston_housing           # Linear regression
cargo run --example logistic_regression      # Binary classification
cargo run --example decision_tree_iris       # Decision tree classifier
cargo run --example random_forest_iris       # Random forest ensemble
cargo run --example gbm_iris                 # Gradient boosting
cargo run --example naive_bayes_iris         # Naive Bayes classifier
cargo run --example knn_iris                 # K-nearest neighbors
cargo run --example svm_iris                 # Support vector machine
cargo run --example regularized_regression   # Ridge/Lasso/ElasticNet

Unsupervised Learning

cargo run --example iris_clustering          # K-Means clustering
cargo run --example dbscan_clustering        # Density-based clustering
cargo run --example hierarchical_clustering  # Agglomerative clustering
cargo run --example gmm_clustering           # Gaussian mixture models
cargo run --example spectral_clustering      # Graph-based clustering
cargo run --example pca_iris                 # Principal component analysis
cargo run --example tsne_visualization       # t-SNE dimensionality reduction

Anomaly Detection

cargo run --example isolation_forest_anomaly # Isolation forest
cargo run --example lof_anomaly              # Local outlier factor

Graph & Association Rules

cargo run --example graph_social_network     # PageRank & centrality
cargo run --example community_detection      # Louvain algorithm
cargo run --example market_basket_apriori    # Association rule mining

Model Selection & Utilities

cargo run --example cross_validation         # K-fold cross-validation
cargo run --example model_serialization      # Save/load models
cargo run --example dataframe_basics         # DataFrame operations
cargo run --example descriptive_statistics   # Statistical analysis
cargo run --example optimizer_demo           # SGD and Adam optimizers

Quality Metrics

• TDG Score: 93.3/100 (A grade)
• Total Tests: 683 passing
• Property Tests: 32 (proptest)
• Doc Tests: 49
• Coverage: ~95%
• Max Cyclomatic Complexity: ≤10
• Clippy Warnings: 0
• SATD Violations: 0 critical (1 low-priority TODO)

Documentation

• EXTREME TDD Book: https://paiml.github.io/aprender/
• API Reference: Run cargo doc --open or visit docs.rs/aprender

Roadmap

See ROADMAP.md for planned features and version roadmap.

License

MIT License - see LICENSE for details.

Contributing

Contributions welcome! Please ensure:

• All tests pass: cargo test --all
• No clippy warnings: cargo clippy --all-targets
• Code is formatted: cargo fmt