Sorting Vectors

Recipe	Crates	Categories
Sort a vector of integers
Sort a vector of floats
Sort a vector of structs

Sort a vector of integers

This example will sort a Vector of integers via std::vec::Vec::sort⮳. Alternative would be to use std::vec::Vec::sort_unstable⮳ which can be faster, but does not preserve the order of equal elements.

fn main() {
    let mut vec = vec![1, 5, 10, 2, 15];

    vec.sort();

    assert_eq!(vec, vec![1, 2, 5, 10, 15]);
    println!("{:?}", vec);
}

Sort a vector of floats

A vector of f32 or f64 can be sorted with sort_by and std::cmp::PartialOrd::partial_cmp⮳.

fn main() {
    let mut vec = vec![1.1, 1.15, 5.5, 1.123, 2.0];

    vec.sort_by(|a, b| a.partial_cmp(b).unwrap());

    assert_eq!(vec, vec![1.1, 1.123, 1.15, 2.0, 5.5]);

    println!("{:?}", vec);
}

Sort a vector of structs

Sorts a vector of Person structs with properties name and age by its natural order (by name and age). In order to make Person sortable you need four traits std::cmp::Eq⮳, std::cmp::PartialEq⮳, std::cmp::Ord⮳ and std::cmp::PartialOrd⮳. These traits can be simply derived. You can also provide a custom comparator function using a std::vec::Vec::sort_by⮳ method and sort only by age.

#[derive(Debug, Eq, Ord, PartialEq, PartialOrd)]
struct Person {
    name: String,
    age: u32,
}

impl Person {
    pub fn new(name: String, age: u32) -> Self {
        Person { name, age }
    }
}

fn main() {
    let mut people = vec![
        Person::new("Zoe".to_string(), 25),
        Person::new("Al".to_string(), 60),
        Person::new("John".to_string(), 1),
    ];

    // Sort people by derived natural order (Name and age)
    people.sort();

    assert_eq!(people, vec![
        Person::new("Al".to_string(), 60),
        Person::new("John".to_string(), 1),
        Person::new("Zoe".to_string(), 25),
    ]);
    println!("{:?}", people);

    // Sort people by age
    people.sort_by(|a, b| b.age.cmp(&a.age));

    assert_eq!(people, vec![
        Person::new("Al".to_string(), 60),
        Person::new("Zoe".to_string(), 25),
        Person::new("John".to_string(), 1),
    ]);

    println!("{:?}", people);
}

Rust How-to

Sorting Vectors

Sort a vector of integers

Sort a vector of floats

Sort a vector of structs

See also