Function plot_learning_curve

src/opt.rs:300–334

Plots the learning curve from an optimization result.

(r: &OptResult<f64>, w: &Window)

/// Plots the learning curve from an optimization result.
///
pub fn plot_learning_curve(r: &OptResult<f64>, w: &Window) -> Result<(String, String), &'static str> {

    let errors = r.fvals.iter().map(|&(_, ref y)| y).cloned().collect::<Vec<f64>>();

    let mut prfx = "/tmp/".to_string();
    prfx.extend(thread_rng().gen_ascii_chars().take(16));

    let script_file = prfx.clone() + ".m";
    let image_file = prfx + ".png";

    let r = builder()
        .add_vector("y = $$", &errors)
        .add("x = 1:size(y, 2)")
        .add("plot(x, y, 'linewidth', 2)")
        .add("grid on")
        .add("title('learning curve')")
        .add("xlabel('iteration')")
        .add("ylabel('error')")
        .add(&("print -r100 -dpng '".to_string() + &image_file + "'"))
        .run(&script_file);

    match r {
        Ok(_) => {
            let img = RgbImage::from_file(&image_file);
            match img {
                Some(i) => {
                    w.show_image(&i);
                    Ok((script_file, image_file))
                },
                _ => Err("Could not load image.")
            }
        },
        _ => Err("Could not run octave.")
    }
}