コサイン類似度の計算

cos_sim.rs

fn cos_sim(q: &Vec<i32>, d: &Vec<i32>) -> f32 {
    assert_eq!(q.len(), d.len());

    // 分母
    let mut dot = 0.0;
    for i in 0..q.len() {
        dot += (q[i] * d[i]) as f32;
    }
    // 分子左
    let mut left = 0.0;
    for i in 0..q.len() {
        left += (q[i] * q[i]) as f32;
    }
    left = left.sqrt();
    // 分子右
    let mut right = 0.0;
    for i in 0..d.len() {
        right += (d[i] * d[i]) as f32;
    }
    right = right.sqrt();
    return dot/(left*right);
}

fn main() {
    let w1 = vec![3, 4, 1, 1, 3];
    let w2 = vec![1, 2, 0, 4, 2];
    let w3 = vec![2, 2, 4, 3, 4];
    let cos_sim_12 = cos_sim(&w1, &w2);
    let cos_sim_23 = cos_sim(&w2, &w3);
    let cos_sim_13 = cos_sim(&w1, &w3);
    println!("cos(w1,w2)={}", cos_sim_12);
    println!("cos(w2,w3)={}", cos_sim_23);
    println!("cos(w1,w3)={}", cos_sim_13);
}