fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut rdr = csv::ReaderBuilder::new()
        .has_headers(true)
        .from_path("data/data.csv")?;

    let mut x_train: Vec<Vec<f64>> = Vec::new();
    let mut y_train: Vec<f64> = Vec::new();

    for result in rdr.records() {
        let record = result?;

        let x1: f64 = record[0].parse()?;
        let x2: f64 = record[1].parse()?;
        let y: f64 = record[2].parse()?;

        x_train.push(vec![x1, x2]);
        y_train.push(y);
    }

    let gp_model = friedrich::gaussian_process::GaussianProcess::default(x_train, y_train);

    let x_test = vec![50.0, 70.0];

    let y_mu = gp_model.predict(&x_test);
    let y_sigma = gp_model.predict_variance(&x_test).sqrt();

    println!("y μ = {}", y_mu);
    println!("y σ = {}", y_sigma);

    println!("{:?}", gp_model.kernel);

    Ok(())
}