Reuse interpolant with different heights

[varchasgopalaswamy]

Hi,

I'm having a use case where I have multiple fields defined on a common interpolation grid. My current implementation is to do something like this

struct PointWithHeight{
    position: Point2<f64>,
    height: f64,
}

impl HasPosition for PointWithHeight {
    type Scalar = f64;

    fn position(&self) -> Point2<f64> {
        self.position
    }
}



pub fn interpolate_field(
    field: &ArrayView2<f64>,
    r_in: &ArrayView2<f64>,
    z_in: &ArrayView2<f64>,
    r_out: &ArrayView2<f64>,
    z_out: &ArrayView2<f64>,
) -> Array2<f64> {
    let mut triangulation = DelaunayTriangulation::<PointWithHeight>::new();
    for ((&r, &z), &value) in r_in.iter().zip(z_in.iter()).zip(field.iter()) {
        let point = PointWithHeight {
            position: Point2::new(r, z),
            height: value,
        };
        triangulation.insert(point).unwrap();
    }

    let mut query_values = Array2::<f64>::zeros(r_out.raw_dim()); 
    let interpolator = triangulation.natural_neighbor();

    Zip::from(&mut query_values).and(r_out).and(z_out).for_each(|qv, &r, &z| {
        let query_point = Point2::new(r, z);
        *qv = interpolator.interpolate(|v| v.data().height, query_point).unwrap_or(f64::NAN);
    });
    return query_values;
}

and then do something like

let interp_f1 = interpolate_field(f1,r,z,r_out,z_out); 
...
let interp_fn = interpolate_field(fn,r,z,r_out,z_out); 

It seems a little wasteful to build the triangulation over and over again. Is there any way to save the triangulation and simply change the field values?