rust-optimizer/examples/parameter_api.rs

use optimizer::prelude::*;
use optimizer_derive::Categorical;

#[derive(Clone, Debug, Categorical)]
enum Activation {
    Relu,
    Sigmoid,
    Tanh,
}

fn main() {
    let study: Study<f64> = Study::new(Direction::Minimize);

    // Define parameters outside the objective function
    let lr_param = FloatParam::new(1e-5, 1e-1).name("lr").log_scale();
    let n_layers_param = IntParam::new(1, 5).name("n_layers");
    let units_param = IntParam::new(32, 512).name("units").step(32);
    let optimizer_param = CategoricalParam::new(vec!["sgd", "adam", "rmsprop"]).name("optimizer");
    let activation_param = EnumParam::<Activation>::new().name("activation");
    let batch_size_param = IntParam::new(16, 256).name("batch_size").log_scale();
    let use_dropout_param = BoolParam::new().name("use_dropout");

    study
        .optimize(20, |trial| {
            let lr = lr_param.suggest(trial)?;
            let n_layers = n_layers_param.suggest(trial)?;
            let units = units_param.suggest(trial)?;
            let optimizer = optimizer_param.suggest(trial)?;
            let use_dropout = use_dropout_param.suggest(trial)?;
            let activation = activation_param.suggest(trial)?;
            let batch_size = batch_size_param.suggest(trial)?;

            // Simulate a loss function
            let loss = lr * (n_layers as f64) + (units as f64) * 0.001
                - if use_dropout { 0.1 } else { 0.0 };

            println!(
                "Trial {}: lr={lr:.6}, layers={n_layers}, units={units}, opt={optimizer}, \
                 dropout={use_dropout}, activation={activation:?}, batch={batch_size} -> loss={loss:.4}",
                trial.id()
            );

            Ok::<_, Error>(loss)
        })
        .unwrap();

    let best = study.best_trial().unwrap();
    println!("\nBest trial: value={:.4}", best.value);
    println!("  lr: {:.6}", best.get(&lr_param).unwrap());
    println!("  n_layers: {}", best.get(&n_layers_param).unwrap());
    println!("  units: {}", best.get(&units_param).unwrap());
    println!("  optimizer: {}", best.get(&optimizer_param).unwrap());
    println!("  activation: {:?}", best.get(&activation_param).unwrap());
    println!("  batch_size: {}", best.get(&batch_size_param).unwrap());
    println!("  use_dropout: {}", best.get(&use_dropout_param).unwrap());
}