Deduplicate elements in Vec in Rust

How to Deduplicate the elements in a Vector

First Version

in the first version of the deduplicate:

• First create data_set to matain the data exists state.
• Iter over the data and check if the specific data in idx is exists
• If exists then skip.
• If not exists then push the data to new result: dedup_data.

fn deduplicate(data: Vec<Vec<String>>, idx: usize) -> Vec<Vec<String>> {
    let mut dedup_data: Vec<Vec<String>> = Vec::with_capacity(data.len() as usize);
    let mut data_set = HashSet::new();
    for record in data {
        let r = record.clone();
        let v = r[idx].clone();
        if data_set.contains(&v) {
            continue;
        }

        data_set.insert(v);
        dedup_data.push(record);
    }

    dedup_data
}

Optimized Version

use vec retain method to Retains only the elements specified by the predicate.

the HashSet insert will return false if the data not exists in the data set. which expected(don't skip the data not exists)

fn deduplicate1(data: &mut Vec<Vec<String>>, idx: usize) {
    let mut data_set = HashSet::new();
    data.retain(|r| data_set.insert(r[idx].clone()))
}