MeiliSearch/meilisearch-core/src/criterion/sum_of_typos.rs

117 lines
2.9 KiB
Rust

use std::cmp::Ordering;
use slice_group_by::GroupBy;
use crate::criterion::Criterion;
use crate::RawDocument;
// This function is a wrong logarithmic 10 function.
// It is safe to panic on input number higher than 3,
// the number of typos is never bigger than that.
#[inline]
fn custom_log10(n: u8) -> f32 {
match n {
0 => 0.0, // log(1)
1 => 0.30102, // log(2)
2 => 0.47712, // log(3)
3 => 0.60205, // log(4)
_ => panic!("invalid number"),
}
}
#[inline]
fn sum_matches_typos(query_index: &[u32], distance: &[u8]) -> usize {
let mut number_words: usize = 0;
let mut sum_typos = 0.0;
let mut index = 0;
for group in query_index.linear_group() {
sum_typos += custom_log10(distance[index]);
number_words += 1;
index += group.len();
}
(number_words as f32 / (sum_typos + 1.0) * 1000.0) as usize
}
#[derive(Debug, Clone, Copy)]
pub struct SumOfTypos;
impl Criterion for SumOfTypos {
fn evaluate(&self, lhs: &RawDocument, rhs: &RawDocument) -> Ordering {
let lhs = {
let query_index = lhs.query_index();
let distance = lhs.distance();
sum_matches_typos(query_index, distance)
};
let rhs = {
let query_index = rhs.query_index();
let distance = rhs.distance();
sum_matches_typos(query_index, distance)
};
lhs.cmp(&rhs).reverse()
}
fn name(&self) -> &str {
"SumOfTypos"
}
}
#[cfg(test)]
mod tests {
use super::*;
// typing: "Geox CEO"
//
// doc0: "Geox SpA: CEO and Executive"
// doc1: "Mt. Gox CEO Resigns From Bitcoin Foundation"
#[test]
fn one_typo_reference() {
let query_index0 = &[0, 1];
let distance0 = &[0, 0];
let query_index1 = &[0, 1];
let distance1 = &[1, 0];
let doc0 = sum_matches_typos(query_index0, distance0);
let doc1 = sum_matches_typos(query_index1, distance1);
assert_eq!(doc0.cmp(&doc1).reverse(), Ordering::Less);
}
// typing: "bouton manchette"
//
// doc0: "bouton manchette"
// doc1: "bouton"
#[test]
fn no_typo() {
let query_index0 = &[0, 1];
let distance0 = &[0, 0];
let query_index1 = &[0];
let distance1 = &[0];
let doc0 = sum_matches_typos(query_index0, distance0);
let doc1 = sum_matches_typos(query_index1, distance1);
assert_eq!(doc0.cmp(&doc1).reverse(), Ordering::Less);
}
// typing: "bouton manchztte"
//
// doc0: "bouton manchette"
// doc1: "bouton"
#[test]
fn one_typo() {
let query_index0 = &[0, 1];
let distance0 = &[0, 1];
let query_index1 = &[0];
let distance1 = &[0];
let doc0 = sum_matches_typos(query_index0, distance0);
let doc1 = sum_matches_typos(query_index1, distance1);
assert_eq!(doc0.cmp(&doc1).reverse(), Ordering::Less);
}
}