# Uniform in rand::distributions - Rust
Sample values uniformly between two bounds.
Keywords: rust, rustlang, rust-lang, Uniform

# Struct rand::distributions::Uniform

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    pub struct Uniform<X: SampleUniform>(_);

Expand description

Sample values uniformly between two bounds.

`Uniform::new` and `Uniform::new_inclusive` construct a uniform distribution sampling from the given range; these functions may do extra work up front to make sampling of multiple values faster. If only one sample from the range is required, `Rng::gen_range` can be more efficient.

When sampling from a constant range, many calculations can happen at compile-time and all methods should be fast; for floating-point ranges and the full range of integer types this should have comparable performance to the `Standard` distribution.

Steps are taken to avoid bias which might be present in naive implementations; for example `rng.gen::<u8>() % 170` samples from the range `[0, 169]` but is twice as likely to select numbers less than 85 than other values. Further, the implementations here give more weight to the high-bits generated by the RNG than the low bits, since with some RNGs the low-bits are of lower quality than the high bits.

Implementations must sample in `[low, high)` range for `Uniform::new(low, high)`, i.e., excluding `high`. In particular, care must be taken to ensure that rounding never results values `< low` or `>= high`.

## Example

    use rand::distributions::{Distribution, Uniform};

    let between = Uniform::from(10..10000);
    let mut rng = rand::thread_rng();
    let mut sum = 0;
    for _ in 0..1000 {
        sum += between.sample(&mut rng);
    }
    println!("{}", sum);

For a single sample, `Rng::gen_range` may be preferred:

    use rand::Rng;

    let mut rng = rand::thread_rng();
    println!("{}", rng.gen_range(0..10));

## Implementations

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### impl<X: SampleUniform> Uniform<X>

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

Create a new `Uniform` instance which samples uniformly from the half open range `[low, high)` (excluding `high`). Panics if `low >= high`.

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

Create a new `Uniform` instance which samples uniformly from the closed range `[low, high]` (inclusive). Panics if `low > high`.

## Trait Implementations

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### impl<X: Clone + SampleUniform> Clone for Uniform<X> where
X::Sampler: Clone,

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#### fn clone(&self) -> Uniform<X>

Returns a copy of the value. Read more

1.0.0 · source

#### fn clone_from(&mut self, source: &Self)

Performs copy-assignment from `source`. Read more

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### impl<X: Debug + SampleUniform> Debug for Uniform<X> where
X::Sampler: Debug,

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#### fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter. Read more

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### impl<X: SampleUniform> Distribution<X> for Uniform<X>

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

Generate a random value of `T`, using `rng` as the source of randomness.

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#### fn sample_iter<R>(self, rng: R) -> DistIter<Self, R, T>ⓘNotable traits for DistIter<D, R, T>`impl<D, R, T> Iterator for DistIter<D, R, T> where
D: Distribution<T>,
R: Rng, type Item = T;` where
R: Rng,
Self: Sized,

Create an iterator that generates random values of `T`, using `rng` as the source of randomness. Read more

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#### fn map<F, S>(self, func: F) -> DistMap<Self, F, T, S> where
F: Fn(T) -> S,
Self: Sized,

Create a distribution of values of ‘S’ by mapping the output of `Self` through the closure `F` Read more

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### impl<X: SampleUniform> From<Range<X>> for Uniform<X>

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#### fn from(r: Range<X>) -> Uniform<X>

Converts to this type from the input type.

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### impl<X: SampleUniform> From<RangeInclusive<X>> for Uniform<X>

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#### fn from(r: RangeInclusive<X>) -> Uniform<X>

Converts to this type from the input type.

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### impl<X: PartialEq + SampleUniform> PartialEq<Uniform<X>> for Uniform<X> where
X::Sampler: PartialEq,

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#### fn eq(&self, other: &Uniform<X>) -> bool

This method tests for `self` and `other` values to be equal, and is used by `==`. Read more

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#### fn ne(&self, other: &Uniform<X>) -> bool

This method tests for `!=`.

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### impl<X: Copy + SampleUniform> Copy for Uniform<X> where
X::Sampler: Copy,

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### impl<X: SampleUniform> StructuralPartialEq for Uniform<X>

## Auto Trait Implementations

### impl<X> RefUnwindSafe for Uniform<X> where
<X as SampleUniform>::Sampler: RefUnwindSafe,

### impl<X> Send for Uniform<X> where
<X as SampleUniform>::Sampler: Send,

### impl<X> Sync for Uniform<X> where
<X as SampleUniform>::Sampler: Sync,

### impl<X> Unpin for Uniform<X> where
<X as SampleUniform>::Sampler: Unpin,

### impl<X> UnwindSafe for Uniform<X> where
<X as SampleUniform>::Sampler: UnwindSafe,

## Blanket Implementations

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### impl<T> Any for T where
T: 'static + ?Sized,

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#### fn type_id(&self) -> TypeId

Gets the `TypeId` of `self`. Read more

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### impl<T> Borrow<T> for T where
T: ?Sized,

const: unstable · source

#### fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more

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### impl<T> BorrowMut<T> for T where
T: ?Sized,

const: unstable · source

#### fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more

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### impl<T> From<T> for T

const: unstable · source

#### fn from(t: T) -> T

Returns the argument unchanged.

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### impl<T, U> Into<U> for T where
U: From<T>,

const: unstable · source

#### fn into(self) -> U

Calls `U::from(self)`.

That is, this conversion is whatever the implementation of `From<T> for U` chooses to do.

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### impl<T> ToOwned for T where
T: Clone,

#### type Owned = T

The resulting type after obtaining ownership.

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#### fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more

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#### fn clone_into(&self, target: &mut T)

🔬 This is a nightly-only experimental API. (`toowned_clone_into`)

Uses borrowed data to replace owned data, usually by cloning. Read more

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### impl<T, U> TryFrom<U> for T where
U: Into<T>,

#### type Error = Infallible

The type returned in the event of a conversion error.

const: unstable · source

#### fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.

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### impl<T, U> TryInto<U> for T where
U: TryFrom<T>,

#### type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.

const: unstable · source

#### fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.

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### impl<V, T> VZip<V> for T where
V: MultiLane<T>,

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#### fn vzip(self) -> V