csaps 0.5.0

Cubic spline approximation (smoothing)
Documentation 
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use approx::assert_abs_diff_eq;
use ndarray::{array, Array1, Axis};

use csaps::CubicSmoothingSpline;

const EPS: f64 = 1e-08;

#[test]
fn test_without_weights_auto_smooth_1() {
    let x = array![1.0, 2.0, 3.0, 4.0, 5.0];
    let y = array![1.5, 3.5, 2.6, 1.2, 4.4];

    let s = CubicSmoothingSpline::new(&x, &y).make().unwrap();

    assert_abs_diff_eq!(s.smooth().unwrap(), 0.8999999999999999);

    let coeffs_expected = array![[
        -0.41780962939499505,
        0.39429046563192893,
        0.6284368070953434,
        -0.6049176433322773,
        0.0,
        -1.253428888184985,
        -0.07055749128919839,
        1.814752929996832,
        1.597869813113715,
        0.3444409249287297,
        -0.979545454545454,
        0.7646499841621794,
        1.7785397529299969,
        2.958599936648717,
        2.44390243902439,
        2.022236300285081,
    ]];

    assert_abs_diff_eq!(s.spline().unwrap().coeffs(), coeffs_expected, epsilon = EPS);

    let ys = s.evaluate(&x).unwrap();

    let ys_expected = array![
        1.7785397529299969,
        2.958599936648717,
        2.44390243902439,
        2.022236300285081,
        3.9967215711118156
    ];

    assert_abs_diff_eq!(ys, ys_expected, epsilon = EPS);
}

#[test]
fn test_without_weights_auto_smooth_2() {
    let x = array![1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0];
    let y = array![1.5, 3.5, 2.6, 1.2, 4.4, 2.2, 1.6, 7.8, 9.1];

    let s = CubicSmoothingSpline::new(&x, &y).make().unwrap();

    let coeffs_expected = Array1::from(vec![
        -0.40104239278928844,
        0.40119697598279225,
        0.4627405882617183,
        -1.0601182231124329,
        0.8508522158245622,
        0.6042037115821123,
        -1.312753456982271,
        0.4549205812328071,
        0.0,
        -1.2031271783678652,
        0.0004637495805114,
        1.3886855143656665,
        -1.7916691549716321,
        0.7608874925020545,
        2.5734986272483913,
        -1.3647617436984212,
        1.5988545517483752,
        0.3957273733805099,
        -0.8069360554068441,
        0.5822132085393337,
        0.17922956793336786,
        -0.8515520945362101,
        2.482834025214236,
        3.6915709087642057,
        1.7673615951928592,
        2.965173754151946,
        2.5589709251473827,
        2.2152392075827683,
        3.1260197073753355,
        2.3644323361616335,
        2.87797144570959,
        6.6215506411899465,
    ])
    .insert_axis(Axis(0));

    assert_abs_diff_eq!(s.spline().unwrap().coeffs(), coeffs_expected, epsilon = EPS);

    let ys = s.evaluate(&x).unwrap();

    let ys_expected = array![
        1.7673615951928592,
        2.965173754151946,
        2.5589709251473827,
        2.2152392075827683,
        3.1260197073753355,
        2.3644323361616335,
        2.87797144570959,
        6.6215506411899465,
        9.403280387488538,
    ];

    assert_abs_diff_eq!(ys, ys_expected, epsilon = EPS);
}

#[test]
fn test_with_weights_and_smooth() {
    let x = array![1.0, 2.0, 3.0, 4.0, 5.0];
    let y = array![1.5, 3.5, 2.6, 1.2, 4.4];
    let w = array![1.0, 0.5, 0.7, 1.0, 0.6];

    let s = CubicSmoothingSpline::new(&x, &y)
        .with_weights(&w)
        .with_smooth(0.8)
        .make()
        .unwrap();

    let coeffs_expected = array![[
        -0.1877506234413966,
        0.18106733167082298,
        0.34543640897755623,
        -0.33875311720698265,
        0.0,
        -0.5632518703241898,
        -0.020049875311720824,
        1.016259351620948,
        0.7996708229426432,
        0.23641895261845425,
        -0.34688279301745645,
        0.6493266832917706,
        1.7816259351620949,
        2.3935461346633415,
        2.247780548628429,
        2.226284289276808
    ]];

    assert_abs_diff_eq!(s.spline().unwrap().coeffs(), coeffs_expected, epsilon = EPS);

    let ys = s.evaluate(&x).unwrap();

    let ys_expected = array![
        1.7816259351620949,
        2.3935461346633415,
        2.247780548628429,
        2.226284289276808,
        3.553117206982544
    ];

    assert_abs_diff_eq!(ys, ys_expected, epsilon = EPS);
}