Trigrams

trigram.rs

#[test]
fn test_trigram() {
    let trigrams = trigram("Hello, wor杯ld!");
    assert_eq!(
        trigrams,
        vec![
            "hel", "ell", "llo", "lo,", "o, ", ", w", " wo", "wor", "or杯", "r杯l", "杯ld", "ld!"
        ]
    );
}

pub fn trigram(word: &str) -> Vec<String> {
    let chars: Vec<char> = word.to_lowercase().chars().collect();

    if chars.len() < 3 {
        return vec![];
    }

    let mut trigrams = Vec::with_capacity(chars.len() - 2);

    for i in 0..chars.len() - 2 {
        let trigram_str: String = chars[i..i + 3].iter().collect();
        trigrams.push(trigram_str);
    }

    trigrams
}

pub fn trigram2(word: &str) -> Vec<(usize, usize)> {
    if word.len() < 3 {
        return vec![];
    }

    let mut trigram_indices = Vec::with_capacity(word.len() - 2);

    for i in 0..word.len() - 2 {
        let trigram_start = i;
        let trigram_end = i + 2;
        trigram_indices.push((trigram_start, trigram_end));
    }

    trigram_indices
}