Rust mean, median, mode algorithms code example

Example: Rust mean, median, mode algorithms

// Rust mean, median, mode algorithms with examples of use
fn mean(arr: &[f64]) -> f64 {
    let sum = arr.iter().fold(0.0, |p,&q| p + q);
    sum / arr.len() as f64
}

fn median(mut xs: Vec<f64>) -> f64 {
    // sort in ascending order, panic on f64::NaN
    xs.sort_by(|x,y| x.partial_cmp(y).unwrap() );
    let n = xs.len();
    if n % 2 == 0 {
        (xs[n/2] + xs[n/2 - 1]) / 2.0
    } else {
        xs[n/2]
    }
}

fn mode(vs: Vec<i32>) -> Vec<i32> {
    use std::collections::HashMap;
    let mut vec_mode = Vec::new();
    let mut seen_map = HashMap::new();
    let mut max_val = 0;
    for i in vs{
        let ctr = seen_map.entry(i).or_insert(0);
        *ctr += 1;
        if *ctr > max_val{
            max_val = *ctr;
        }
    }
    for (key, val) in seen_map {
        if val == max_val{
            vec_mode.push(key);
        }
    }
    vec_mode
}
 
fn main() {
    let v = &[2.0, 3.0, 5.0, 7.0, 13.0, 21.0, 33.0, 54.0];
    println!("mean of {:?}: {:?}", v, mean(v));
 
    let w = &[];
    println!("mean of {:?}: {:?}", w, mean(w));
    
    println!("median of {:?}: {:?}", v, median(v.to_vec()));
    
    let mode_vec1 = mode(vec![ 1, 3, 6, 6, 6, 6, 7, 7, 12, 12, 17]);
    let mode_vec2 = mode(vec![ 1, 1, 2, 4, 4]);
 
    println!("Mode of vec1 is: {:?}", mode_vec1);
    println!("Mode of vec2 is: {:?}", mode_vec2);    
}