Trait genevo::random::SliceRandom

source · [−]
pub trait SliceRandom {
    type Item;
    fn choose<R>(&self, rng: &mut R) -> Option<&Self::Item>
    where
        R: Rng + ?Sized;

    fn choose_mut<R>(&mut self, rng: &mut R) -> Option<&mut Self::Item>
    where
        R: Rng + ?Sized;

    fn shuffle<R>(&mut self, rng: &mut R)
    where
        R: Rng + ?Sized;

    fn partial_shuffle<R>(
        &mut self, 
        rng: &mut R, 
        amount: usize
    ) -> (&mut [Self::Item], &mut [Self::Item])
    where
        R: Rng + ?Sized;
}
Expand description

Extension trait on slices, providing random mutation and sampling methods.

This trait is implemented on all [T] slice types, providing several methods for choosing and shuffling elements. You must use this trait:

use rand::seq::SliceRandom;

let mut rng = rand::thread_rng();
let mut bytes = "Hello, random!".to_string().into_bytes();
bytes.shuffle(&mut rng);
let str = String::from_utf8(bytes).unwrap();
println!("{}", str);

Example output (non-deterministic):

l,nmroHado !le

Associated Types

The element type.

Required methods

Returns a reference to one random element of the slice, or None if the slice is empty.

For slices, complexity is O(1).

Example
use rand::thread_rng;
use rand::seq::SliceRandom;

let choices = [1, 2, 4, 8, 16, 32];
let mut rng = thread_rng();
println!("{:?}", choices.choose(&mut rng));
assert_eq!(choices[..0].choose(&mut rng), None);

Returns a mutable reference to one random element of the slice, or None if the slice is empty.

For slices, complexity is O(1).

Shuffle a mutable slice in place.

For slices of length n, complexity is O(n).

Example
use rand::seq::SliceRandom;
use rand::thread_rng;

let mut rng = thread_rng();
let mut y = [1, 2, 3, 4, 5];
println!("Unshuffled: {:?}", y);
y.shuffle(&mut rng);
println!("Shuffled:   {:?}", y);

Shuffle a slice in place, but exit early.

Returns two mutable slices from the source slice. The first contains amount elements randomly permuted. The second has the remaining elements that are not fully shuffled.

This is an efficient method to select amount elements at random from the slice, provided the slice may be mutated.

If you only need to choose elements randomly and amount > self.len()/2 then you may improve performance by taking amount = values.len() - amount and using only the second slice.

If amount is greater than the number of elements in the slice, this will perform a full shuffle.

For slices, complexity is O(m) where m = amount.

Implementations on Foreign Types

Implementors