Trait rand::distributions::uniform::UniformSampler

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pub trait UniformSampler: Sized {
    type X;
    fn new<B1, B2>(low: B1, high: B2) -> Self
    where
        B1: SampleBorrow<Self::X> + Sized,
        B2: SampleBorrow<Self::X> + Sized;
    fn new_inclusive<B1, B2>(low: B1, high: B2) -> Self
    where
        B1: SampleBorrow<Self::X> + Sized,
        B2: SampleBorrow<Self::X> + Sized;
    fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> Self::X;

    fn sample_single<R: Rng + ?Sized, B1, B2>(
        low: B1, 
        high: B2, 
        rng: &mut R
    ) -> Self::X
    where
        B1: SampleBorrow<Self::X> + Sized,
        B2: SampleBorrow<Self::X> + Sized,
    { ... }
}

Expand description

Helper trait handling actual uniform sampling.

See the module documentation on how to implement Uniform range sampling for a custom type.

Implementation of sample_single is optional, and is only useful when the implementation can be faster than Self::new(low, high).sample(rng).

Associated Types

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type X

The type sampled by this implementation.

Required methods

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fn new<B1, B2>(low: B1, high: B2) -> Self where
B1: SampleBorrow<Self::X> + Sized,
B2: SampleBorrow<Self::X> + Sized,

Construct self, with inclusive lower bound and exclusive upper bound [low, high).

Usually users should not call this directly but instead use Uniform::new, which asserts that low < high before calling this.

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fn new_inclusive<B1, B2>(low: B1, high: B2) -> Self where
B1: SampleBorrow<Self::X> + Sized,
B2: SampleBorrow<Self::X> + Sized,

Construct self, with inclusive bounds [low, high].

Usually users should not call this directly but instead use Uniform::new_inclusive, which asserts that low <= high before calling this.

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fn sample<R: Rng + ?Sized>(&self, rng: &mut R) -> Self::X

Sample a value.

Provided methods

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fn sample_single<R: Rng + ?Sized, B1, B2>(
    low: B1,
    high: B2,
    rng: &mut R
) -> Self::X where
    B1: SampleBorrow<Self::X> + Sized,
    B2: SampleBorrow<Self::X> + Sized,

Sample a single value uniformly from a range with inclusive lower bound and exclusive upper bound [low, high).

By default this is implemented using UniformSampler::new(low, high).sample(rng). However, for some types more optimal implementations for single usage may be provided via this method (which is the case for integers and floats). Results may not be identical.

Note that to use this method in a generic context, the type needs to be retrieved via SampleUniform::Sampler as follows:

use rand::{thread_rng, distributions::uniform::{SampleUniform, UniformSampler}};
fn sample_from_range<T: SampleUniform>(lb: T, ub: T) -> T {
    let mut rng = thread_rng();
    <T as SampleUniform>::Sampler::sample_single(lb, ub, &mut rng)
}