c45bab491a
* Improve features * Add wasm32-wasi as a target * Update .github/workflows/ci.yml Co-authored-by: morenol <22335041+morenol@users.noreply.github.com>
87 lines
2.4 KiB
Rust
87 lines
2.4 KiB
Rust
//! # Hamming Distance
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//!
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//! Hamming Distance measures the similarity between two integer-valued vectors of the same length.
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//! Given two vectors \\( x \in ℝ^n \\), \\( y \in ℝ^n \\) the hamming distance between \\( x \\) and \\( y \\), \\( d(x, y) \\), is the number of places where \\( x \\) and \\( y \\) differ.
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//!
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//! Example:
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//!
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//! ```
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//! use smartcore::metrics::distance::Distance;
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//! use smartcore::metrics::distance::hamming::Hamming;
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//!
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//! let a = vec![1, 0, 0, 1, 0, 0, 1];
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//! let b = vec![1, 1, 0, 0, 1, 0, 1];
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//!
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//! let h: f64 = Hamming::new().distance(&a, &b);
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//!
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//! ```
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//!
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//! <script src="https://polyfill.io/v3/polyfill.min.js?features=es6"></script>
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//! <script id="MathJax-script" async src="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js"></script>
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#[cfg(feature = "serde")]
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use serde::{Deserialize, Serialize};
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use std::marker::PhantomData;
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use super::Distance;
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use crate::linalg::basic::arrays::ArrayView1;
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use crate::numbers::basenum::Number;
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/// While comparing two integer-valued vectors of equal length, Hamming distance is the number of bit positions in which the two bits are different
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#[cfg_attr(feature = "serde", derive(Serialize, Deserialize))]
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#[derive(Debug, Clone)]
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pub struct Hamming<T: Number> {
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_t: PhantomData<T>,
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}
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impl<T: Number> Hamming<T> {
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/// instatiate the initial structure
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pub fn new() -> Hamming<T> {
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Hamming { _t: PhantomData }
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}
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}
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impl<T: Number> Default for Hamming<T> {
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fn default() -> Self {
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Self::new()
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}
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}
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impl<T: Number, A: ArrayView1<T>> Distance<A> for Hamming<T> {
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fn distance(&self, x: &A, y: &A) -> f64 {
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if x.shape() != y.shape() {
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panic!("Input vector sizes are different");
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}
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let dist: usize = x
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.iterator(0)
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.zip(y.iterator(0))
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.map(|(a, b)| match a != b {
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true => 1,
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false => 0,
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})
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.sum();
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dist as f64 / x.shape() as f64
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}
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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#[cfg_attr(
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all(target_arch = "wasm32", not(target_os = "wasi")),
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wasm_bindgen_test::wasm_bindgen_test
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)]
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#[test]
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fn hamming_distance() {
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let a = vec![1, 0, 0, 1, 0, 0, 1];
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let b = vec![1, 1, 0, 0, 1, 0, 1];
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let h: f64 = Hamming::new().distance(&a, &b);
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assert!((h - 0.42857142).abs() < 1e-8);
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}
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}
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