interp1d: A simple, lightweight interpolation library written in Rust

This library is intended to be very simple and lightweight. The core Interp1D struct takes some set of (x, y) pairs and has a simple linear interpolation method. Unlike other libaries I found, this libary is unique in two cores ways:

1. It takes ownership over the (x, y) pairs and internally sorts them, using a binary search to find the two neighbors with which interpolation is done. This prevents the sorting/searching that other functions fn(&[T], &[T], T) -> T may do.

2. It allows for the types of x and y to differ. x could be an integer or a float and can be of a different type than y (y must still be a float). This allows for e.g. interpolation on a 1D lattice.

Simple Usage

An example with double precision floats:

use interp1d::Interp1d;


fn main() {

    // Data (already sorted)
    let x: Vec<f64> = vec![1.0, 2.0, 3.0];
    let y: Vec<f64> = vec![5.0, 3.0, 4.0];

    // Using `new_sorted` since data is already sorted
    let interpolator = Interp1d::new_sorted(x, y).unwrap();

    // Points at which we wish to interpolate
    let x_interp = vec![1.5, 2.5];

    // Intepolate with checked fn
    let y_interp: Vec<f64> = x_interp
        .iter()
        .map(|&x| interpolator.interpolate_checked(x))
        .collect::<Result<Vec<f64>, _>>()
        .unwrap(); // all points are in the domain in this example
    
    println!("y_interp = {y_interp:?}");
    // Output:
    // y_interp = [4.0, 3.5]
}

An example with x as usize:

use interp1d::Interp1d;


fn main() {

    // Data (already sorted)
    let x: Vec<usize> = vec![1, 3, 5];
    let y: Vec<f64> = vec![5.0, 3.0, 4.0];

    // Using `new_sorted` since data is already sorted
    let interpolator = Interp1d::new_sorted_int(x, y);

    // Points at which we wish to interpolate
    let x_interp = vec![2, 4];

    // Intepolate with checked fn
    let y_interp: Vec<f64> = x_interp
        .iter()
        .map(|&x| interpolator.interpolate_checked(x))
        .collect::<Result<Vec<f64>, _>>()
        .unwrap(); // all points are in the domain in this example
    
    println!("y_interp = {y_interp:?}");
    // Output:
    // y_interp = [4.0, 3.5]
}