Struct eddie::Hamming

pub struct Hamming { /* fields omitted */ }

Hamming distance.

See the detailed description.

Usage

use eddie::Hamming;

let hamming = Hamming::new();
let dist = hamming.distance("martha", "marhta");
assert_eq!(dist, Some(2));

Returns None if strings have different lengths:

let dist = hamming.distance("martha", "march");
assert_eq!(dist, None);

Complementary metrics

Relative distance:

let rel = hamming.rel_dist(s1, s2)?;
let dist = hamming.distance(s1, s2).map(|d| d as f64)?;
let max_len = max(s1.len(), s2.len()) as f64;
assert_eq!(rel, dist / max_len);

Similarity:

let rel = hamming.rel_dist(s1, s2)?;
let sim = hamming.similarity(s1, s2)?;
assert_eq!(sim, 1.0 - rel);

Methods

impl Hamming

pub fn new() -> Self

Creates a new instance of Hamming struct with an internal state for the metric methods to reuse.

Example

use eddie::Hamming;

let hamming = Hamming::new();

pub fn distance(&self, str1: &str, str2: &str) -> Option<usize>

Distance metric. Returns a number of positions at wich string characters are different.

Returns None if strings have different lengths.

Example

let dist1 = hamming.distance("martha", "marhta");
assert_eq!(dist1, Some(2));

let dist2 = hamming.distance("martha", "march");
assert_eq!(dist2, None);

pub fn rel_dist(&self, str1: &str, str2: &str) -> Option<f64>

Relative distance metric. Returns a distance relative to the string length, ranging from 0.0 (equality) to 1.0 (nothing in common).

Returns None if strings have different lengths.

Example

let dist1 = hamming.rel_dist("martha", "marhta")?;
assert!((dist1 - 0.333).abs() < 0.001);

let dist2 = hamming.rel_dist("martha", "march");
assert_eq!(dist2, None);

pub fn similarity(&self, str1: &str, str2: &str) -> Option<f64>

Similarity metric. Inversion of relative distance, ranging from 1.0 (equality) to 0.0 (nothing in common).

Returns None if strings have different lengths.

Example

let sim1 = hamming.similarity("martha", "marhta")?;
assert!((sim1 - 0.666).abs() < 0.001);

let sim2 = hamming.similarity("martha", "march");
assert_eq!(sim2, None);