162bed2aa2
* test: run tests also in wasm targets * fix: install rand with wasm-bindgen por wasm targets * fix: use actual usize size to access buffer. * fix: do not run functions that create files in wasm. * test: do not run in wasm test that panics. Co-authored-by: Luis Moreno <morenol@users.noreply.github.com>
66 lines
1.9 KiB
Rust
66 lines
1.9 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::math::distance::Distance;
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//! use smartcore::math::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 {}.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 crate::math::num::RealNumber;
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use super::Distance;
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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 {}
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impl<T: PartialEq, F: RealNumber> Distance<Vec<T>, F> for Hamming {
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fn distance(&self, x: &Vec<T>, y: &Vec<T>) -> F {
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if x.len() != y.len() {
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panic!("Input vector sizes are different");
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}
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let mut dist = 0;
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for i in 0..x.len() {
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if x[i] != y[i] {
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dist += 1;
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}
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}
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F::from_i64(dist).unwrap() / F::from_usize(x.len()).unwrap()
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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(target_arch = "wasm32", wasm_bindgen_test::wasm_bindgen_test)]
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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 {}.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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