kernel_density_estimation/kernel/
triangular.rs

1//! Triangular kernel function.
2
3use crate::float::KDEFloat;
4use crate::kernel::Kernel;
5
6/// Triangular kernel function.
7#[derive(Clone, Copy, Debug)]
8pub struct Triangular;
9
10impl<F: KDEFloat> Kernel<F> for Triangular {
11    fn pdf(&self, x: F) -> F {
12        let abs_x = x.abs();
13        if abs_x <= F::one() {
14            F::one() - abs_x
15        } else {
16            F::zero()
17        }
18    }
19}
20
21#[cfg(test)]
22mod tests {
23    use super::Triangular;
24    use crate::kernel::Kernel;
25    use approx::*;
26
27    #[test]
28    fn triangular() {
29        let kernel = Triangular;
30
31        let x = -1.0;
32        let res = kernel.pdf(x);
33        assert_relative_eq!(res, 0.0);
34
35        let x = 0.0;
36        let res = kernel.pdf(x);
37        assert_relative_eq!(res, 1.0);
38
39        let x = 1.0;
40        let res = kernel.pdf(x);
41        assert_relative_eq!(res, 0.0);
42    }
43}